I have a standard 135cc motorcycle using a 25mm carburetor. I upgraded it to 150cc with some other upgrade such as racing camshaft, high-compression piston, bigger valve, K&N round air filter, leovince exhaust... and I used a 30mm CV carb , it works ok with good performance. And then I kept the 150cc bore and downgraded to standard camshaft, lower comprestion piston, smaller valve and original exhaust, stock air box filter, but I kept the 30mm CV carb and it didn't work well even though I tried to adjust it. And I replaced the 25mm carburetor and it worked great.
Great video! I have a small 125cc Suzuki (Address 125/FL125/Shogun125, various names in different areas). Since the EFI unit went bad (costs like 300-350 euros to get a new one), I went with the good old way. Converted to carburetor (the Asian version comes with a 18mm Mikuni VM) and used a Keihin PZ 18mm one. Engine had good low-end torque but lacked power on the top-end. Meanwhile, I had literally zero experiance with carburetors. Stupid me, went on to get an OKO PWK26...I tried different jets (32,34,36,37....105,110,115,125...) but still the bike couldn't keep itself idling for more than a minute. Low-end the engine was like "choking", top end power was good but I felt like it was lacking something. After about 2 weeks of torture with the OKO, I sold it and got a 22mm one. To my surprise the bike runs great! Didn't have to get into jetting, only had to adjust the idle speed a bit. Both low-end and top-end is good and even in cold temperatures, the choke works well so far.
Okay o find this funny I have a 30mm pwk carb on a 50cc! And it runs great it idles better than ever. it rides smooth. But remember my stock carb was a 17mm carb
You sir have answered a lot of questions I had about upgrading to a bigger carb and informed info's I never knew I needed. Big thanks. Your channel is great.
I just wanna run this f7. Bad 26mm carb missing everything inside. Now i need to dig around and see what carbs i have around here. I know i have a brand new 24mm mikuni. Its too small but atleast now i know ill have tons of low end power to put-put around in the corn field
I guess it all comes down to the idle and max rpm’s mandatory cfm “cubic feet per minute “ of air. And the carburetor must be able to perform at both ends of those requirements. The inability to do so will starve the engine for fuel or flood it with too much fuel in the air to fuel mixture.
@@booz8313 i can respect that. Currently running a 80cc derbi with a 28mm as well. The thing rips so much you can hear it sucking all the air in. It's crazy b
There’s no solid formula for the ratio of carb size to capacity especially since multiple different engines of the same cc can use vastly different carb sizes
Maybe u gotta try each size, but thats gonna costs a lil bit In my case im using 30mm carb on my bike, but the performance only good starting middle rpm to high rpm. Low rpm quite poor performance, it feels heavy. I need to downgrade to 28mm carb to get good at low rpm. Since im using it for daily. Unless im going for touring, then i would use 30mm back.
you have to measure the ports and that determines what size carb you get and the most you can get out of it like it determines the biggest one you can get for your bike
Yes. And this video is part of a larger series on carburetors in general. I have an entire page on my website dedicated to all information centered around carburetors and tuning.
I went from 24mm to 32mm flat slide with upgraded 7mm lift cam. The engine is 200cc single cylinder pushrod type. It runs good. Though sometimes there's a little bog on mid throttle and sometimes the idle is not stable. I'm thinking that it could be a faulty needle. But its true, at high RPM, it runs like a beast, and its a lot of fun. At low RPM, it pulls like a champ as well. Its just that mid throttle and idle that bothers me sometimes.
It you find that lifting off the throttle makes it try to go, its running weak in that area. or rich if you get nothing from lifting. Mid range, try lifting the needle by lowering the clip if it has one.
Roundslides seem to be easier to tune same diameter i ran a flatslide 30 on my 150 changed it to a nibbi 30mm ran way better for some reason if u run pwks they dont seem to run how u want them on a 4 stroke
Got a 4 valve zs212cc and I got a 500 dollar proper motorbike carby I wanna use ids 33mm how would I make this work on a 28mm/30mm manifold any help be appreciated thank you ??
on my snorkeled 4wheeler i used pvc no air box just a boot i have a ball valve on the stack to change the air flow if it is all the way open it bogs at wot i close it about 1/4 way to tune top end works for me 30 mm carb 230 cc quadrunner
If the carb is a 30mm and the port or opening in the head is 24mm you create a bunch of turbulence in the flow. you might be able to make the bike run but that trubulence can make it hyper-finky to tune and then you have to get into the other things like cams and valve diameters and exhaust and and and.. but the first step should always be matching the carb to the port.
I’ve got an aprilia rs125 2005 unrestricted 28mm carb and I was thinking if I put a bigger carb it’ll go even faster, but I also want to wheelie in first😂
I was confused about the decision to buy "Mikuni VM Series Carburetors VM26-8074" or " Mikuni TM Series Carburetors VM28-418" for my Yamaha Rx100 which has an oversize imported piston, but I'm clear now thanks to Junkman for the crisp and easy explanation, I'm going with 26mm.!
What is your advisable for my 125cc china bike .I'm using 26mm nibbie super sport.my problem is it's good on idle and 1/4 throttle but when I rev up my engine slows down
I have a brand new 230cc 4stroke dirt bike with a 28mm carb, I cannot seem to eliminate the idle to wide open bog, and it falls on its face type of bog not just a slight hesitation... any ideas? I have tried so many settings and jets with it to no avail?
I have a problem with this tool, it's a KTM 250 2T The tool has not been used for almost a year This week I found time to take care of it, I did a fuel-oil change, I cleaned the filter plug, everything, finally I tried to start it, but the car could not start. It only started with carburetor spray and shut off straight away From that I understood that the carburetor needed to be cleaned and that's how I did it. Now the problem is different, the motorcycle drives straight up to very, very high turns I played with the air-fuel screw but unfortunately it didn't help. Is there a situation where the problem is different? Something in the carburetor maybe? need help please
let me honest with ya only idiot people put 28mm carb on 57mm blok xD even my self, only using 26mm carb cause my intake valve was 31mm ex 25mm cause I was concern bout to match intake diaeter with carb diameter size for better engine performance...... cause I be honest with ya, intake diamter on the head, should be less 10 percent thant valve intake size, like was I had, 31mm in valve, so I should use atleast 28 in diameter hole in the head, also match with intake manifold should be in 28mm and also the carb should be 28mm to for stable air flow, but 28mm carb diameter was 29 mm, so, using 26mm should be enough for had decent airspeed flow through that carb... I tell this I'am already did this before and it's run fine without any problem like bog or something like that. and also, try multiple pilot jet and main jet for better throthole response.. cyaaaa
Ive always found sizing weird. My 150cc scooter engine popularly uses a 28mm carb when built up a bit, and yet built predator 212s use a 24mm at full built capacity
Well it sort of works like this. Smaller bore will maintain velocity which is good for low end torque. On the converse larger bore carburetors favor high rpm power. Intake valve size, duration, lobe separate of the camshaft and cylinder head design and volume all play a part in determining optimal carburetor sizing.
Your camshaft documentation should give you some guidelines on the size. It will also depend on your intake manifold. Something like a 500-650 cfm should be just right.
Just a question, how to determine which main jet size is to be used on a certain carburetor? For example, what size of main jet should i use for a 27mm carburetor round slide?
If you measure the slide on the left carburetor,you will notice that the slide will be narrower than the opening going to the engine(around to 20mm). This is the reference i take in mind in order to measure, because the air will always have the speed of the narrowest point on the whole intake. Am i wrong here?
I have a twin cylinder Honda CD125 Twin Bike with CB points and a 6V system. My engine is running smoothly and with more pulling power at cold weather, Early in the morning and at night. But when I ride during the day when the atmosphere is hotter then the engine is not running smoothly and the engine power is lower with increased engine noise and engine vibration. When I happen to ride from hot atmosphere into cold atmosphere due to raining on the road immediately the engine is begining to run smoothly with less engine noise, with less engine vibration and increased engine power. I wanted the engine always run smoothly as It was in the early days that bought it. On this matter I had many technicians try their skills on my bike and non of them were so far able to solve my problem and bring the engine back to the performance at early days. I am still wondering what could the reason be. Hope to have an efficient answer and advises to regain my engine performances. Thank you in advance....
Question. On a 125 honda cm twin with pod filter and slightly modified exhaust, comes from stock with a 26 mm carb. Would you recommend go higher on main jet or go to a pz30 and decrease main jet size? Thanks
I built a 2018 honda 250x 4wheeler for my nephew with a high compression piston, opened up exhaust, opened air box and jetted carb. I was surprised to see it came with only a 20mm carb being a 229cc with around 18hp stock. Would I gain anything from a bigger carb?? I can't find an example anywhere of anyone putting a bigger carb on one of these. Seeing that most 125-140cc engines come with a 20-22mm carb and even the 6hp go karts run that or bigger makes me think that these are undersized and maybe I could gain a lot from a 28mm or so?? Any advice would be appreciated!
I have a klx 143 v1 head it's a trail bike I believe same with the 26mm carb its cold here but I put a bigger jet and dropped the clip to the bottom plug is dark and oily I'm going to get some fatter jets and play around more
I have a Chinese cool strip 125CC and it has PZ19 stock carb on it. Is there any point in putting a 24 or 26 mm carb on it then would I have to get an intake Adapter boot? Do I have the wrong thinking about this whole deal?I just want the bike to idle and run better these carbs I keep buying for For 18 to $30 just don't seem to be doing Right and definitely not very long.
Depends if the head will flow that much more. I have a big valve head and high lift cam using a 26mm on my CRF50 with a bbk 140cc. You sacrifice low end grunt for getting out of the whole but the mid is nice and meaty.
I wanted to change my carburator from 150cc stock to 100cc carburator for my scooter due to high gas consumption can anyone guide me if this modification is good
Is there a ratio for engine size to carburettor I have a royal Enfield classic 500 which is a long stroke thumper with a 33 mm carb and I have other smaller 200 cc bikes with the same size my plan is to upgrade the 500 to a 42 mm carb with a longer manifold to get better mixing of the gas and adjust the cam timing for rpm will it work or will it stutter midrange I did the same on a custom 200 wher I over bored the engine from 160 cc to 200 it had issues with mixing the fuel past 4000 rmp
It would be nice if it were as simple as Displacement : Carb size, but there are too many factors in that affect what the engine requires as far as carburation is concerned. I may do a future LIVE Q/A and go over this as it is a lengthy explanation that ends with a "it depends". For you it is largely going to be a trial and error process to get a carburetor sizing and jetting dialed in given the modifications you plan to make.
Hi. I have recently developed a hobby of putting carburetors on non-carbureted engines. Currently I am running a Honda D15B (1493cc 16 valve) with a VW 30/31 (designed for 8 valve 1600cc). It runs great and I am super proud. However, I am flirting with the idea of creating a dual carb manifold. Do you think would be able to run a 2 VW carbs with only some minor adjustments? I feel like it would either *just work* or I would run into a rich condition. I cant find a guide online, do you have any incite? Thanks :)
Hey, new subscriber here! I also have a 125cc, changed the block/piston to 56mm now its a 135cc, same deal im using a 28mm carb, regrind cams, intake and exhaust ports are ported and polished(which some people said were too big), big valves, free flow exhaust. with all these mods i only gained little power and it is so hard to tune. So Watching ur video convinced me or made me suspect that my carb is too big for my engine. I also heard that bigger intake ports could lower velocity. Do you think reducing the size of the intake ports could increase power or atleast increase velocity of the air fuel flow? Or should I get bigger cams to compensate with the big carb and ports? What are your suggestions?
It depends on what you want to achieve. Re shaping ports is not an amateur job, especially if you are trying to optimize flow characteristics. I would make sure you have a cam that has enough duration and overlap to keep the air moving and fuel atomized.
i just recently did the same thing got a whole new top end bigger piston to a 56mm which stock is 52 on the 125cc same thing i got valves done 7.0 camshaft and a 28 mm carb should be perfect for the bike try getting more performance stuff to help the tunes more like get a different cdi box different coil for the bike that’s what i did helps with better timing and stuff and get all the power you really want in the bike i had got a 30 mm it works but i feel like going down to a 28 it’s way better and should be perfect
@@thejunkman great video brother, do keep up the good work...I have a quick question for you concerning cvk carb vs the slide type , I have a Honda storm 125 cc and I have noticed that ever since I bought it brand new ,the start up is ok but sluggish when accelerating, I've noticed the same thing with guys who have the same type of bike , after research I've found that the diaphragm type carbs are much slower in reaction to the slide type ...my question is is there anything that can be done to improve the throttle lag and also can I swap out the cvk for a mikuni , if so what size do I purchase and what else do for the mikuni to work? Thanks in advance
@@deniscastro2880 problem here in Philippines their is alot of 2 stoke dirt bikes running around in 125cc and the 28mm works ok with reeds, not so with 4 stokes.
i dont really know a lot about this but if you have a big carb, why wouldn't it idle well? at idle, the air goes through the idle circuit instead of the venturi right? so how does it impact the idle?
The venturi does still play a factor as well as the pilot circuit design/size. However its the off idle performance that could suffer if too drastic of a size change is used.
I have a superstomp 125 (chinese), completely stock. It bogs down in high revs but iv checked the carb and the jets are squeeky clean. Iv heard the stock carbs on chinese pit bikes are trash so maybe could do with being upgraded. What size carb would be best. I heard you say 24mm in the video. Great video btw and thank you.
Your carb is fine, it just needs to be richer on the 3/4-full throttle. You need to see my jetting videos. This is fixable. Stock Chinese carbs are jetted kinda lean for importation purposes.
I have 1 motorcycle 2 stroke at the same time my standard bore stroke are 57mmX54mm.my question,what size bore or piston i need to use carburetor size 58mm for dragrace?
the stock carburetor will be fine, just re-jet as necessary. However if you have a CV type a change to a piston or mechanical slide type would be preferable. See my other videos on that. th-cam.com/video/i6yOd2lwwDU/w-d-xo.html&t
Hello what would be your recomendation on a 150cc with a full system on also Racing CDI, Coils and spark plug and a couple more mods, I’m trying to reach the maximum performance out of it. I’m looking between a Nibbi PWK26mm or PWK28mm which one should you recommend? My stock carburetor it’s a Pz27 which measures 27mm on the cylinder side! Thanks a lot sir I would really really appreciate your thoughts on this matters since I’m new to it
Please respond!!! I don't want to blow up my engine again I have a 96 Polaris XLT special with a 580 monoblock comes with 38 mm mikuni's the sled I am currently building had 34 mm mikuni's I took the 38s and put them on the sled I'm riding that had 34s is this going to be okay the other day I blew up the original engine that had the 34s on it had to pull another engine from a different sled out back that had 34s on it that's the one I put the 38s on sorry about the long comment but I don't want to seize another engine this one has awesome compression
There are more factors than carburation at play when an engine seizes. So that might have not been the issue. If you are worried start off with a bit richer fuel mixture, test, then fine tune the jetting leaner doing plug inspections regularly. And if that sled uses oil injection be sure the system is blead properly.
I have a 200cc scooter that I changed the carburetor to a 30mm and it'll start,idle,and drive in the low rpms but past about quarter throttle it bogs down and starts popping..... Any suggestions on the jetting or adjustments that I can make to get those about quarter throttle rpms???
It will probably work from a design standpoint, however it probably will not bolt up being the mounting points and cylinder port is in a different place so the bends won't make it physically fit.
Hi Junkman. I have a project bike a 78 dt400. It has a 34mm round slide. I would like to try a 36 mm flat slide carb. I was wondering if for a given size round slide vs. flat side mikuni carb is the float tower talker in the flat slide. I have limited clearance above my stock 34mm round slide as the pipe crosses above it.
Cool video, so what if you had say a Keihin Pb18 and the Mikuni equivalent.....they would still have slightly different attributes? Like more adjustability of each circuit?
Great video! I wondered if you could help.. I'm fitting a Rotax 257 single; 2 Stroke (kart engine) to a bike; any ideas what size Carb i should be looking for for optimum mid/high rev range? i think* stock was a mikuni 38mm carb but not 100%. Any advice would be amazing! Steve
What is symptom of too big of carburator? Hard starting? I have a tpr 86cc 2 stroke with 30mm flat pwk polini with vforce3 reeda on a yamaha zuma. It is alwyas hard to cold start it. Once it started, starting is no problem,idle is perfect, it rips too on all throttle range.. It is just the starting that i am having trouble with. It basically floods my exhaust maybe around 10kicks with 1/2 throttle before it even start. Choke doesnt do nothing. I have highher chance of starting it with pulled throttle up to 1/2. Thanks!!
It doesn't really work that way. Honda tried it for 2 years in the 80's with their XR350 and it didn't work well and was a nightmare to make run right.
Hey me I got a 2 stroke blaster I cleaned the original carb still over flowed ajusted the needle still over flowed bought a new stock crab put it on and same thing it over flowed I don’t know what to do at this point and all the shops around me are booth
question, i know its odd that a certified master mechanic should know this, but i was given a nibbi racing 24mm output dia with a larger 35mm intake dia as my OEM carb. oem carb is a 33 input, 30 output. nibbi is a 35 input, 24 output. id assume that this carb would lack airflow if i were to boot it to my 250cc 4 stroke's intake. I dont want to lean my engine, I'm okay with a small loss of power, shes an in town putt-round anyway, but more low throttle power is desireable. ive never asked the question, cam i down size my carb and not suffer too many losses, maybe even experience some gains in fuel economy.
Pffff ! You only spoke trash. From experience I can tell you ,that a 21mm can be replaced with a 28 mm with no problem ! Whatever youve said it is just to superficial.
I love the t shirt. Thanks for the video. I have a paramotor (basically a chainsaw engine. I realised I had tuned the carb with a spacer missing between the carb and engine. It ran well but when I replaced the spacer (only around 10mm thick effectively pulling the carb further from the engine) it leaned out. Fuel air mix had not changed at all but it leaned out so much it would not run anything other than tick over. Any idea why this would happen ?
You will like a engine with the right carburetor much better than a engine with a large carburetor! It's not going to be that noticable, if you can't enjoy the ride to the high rpm! Basically 2mm larger for more power, 4mm larger if you big bore and cam, port the head, and air filter, and free flowing exhaust, to get more flow for the 4mm larger carb, a 50 cc engine I been working with I went from 39mm bore to 50mm, with a head with larger valves, from 16/18mm, to 18/21mm, with ported head, cam. Exhaust, and from 19mm to 20 mm carb, it still has lots of low end throttle response, but stock type CV carbs are not that available, they come in 18,19, and 20, then 24,28,mm. The 24mm is too much, it idles, but will not rev, it can't pick up enough fuel, too much air, and would be alot of work to get it to run crappy, ( the 24mm is for 125-150 cc in this family of engine) most 150-170 use a 26-28mm, I did find a Yamaha, CV carb that I modified to fit. It is 22mm, it should work, maybe with some further mods, jets and tuning, but I think I'll save it for my 52.4mm bore kit, getting closer to 100cc, being the carb is for a 125cc Yamaha, my engine does spin a bit higher than the stock version peaking at 8500, I have seen 10300 rpm, I try to keep it below 9500-9800, the stock carb didn't want to rev past 9k, great video, it explains things well,
Just saw your vid. My question is the bike I juts got, 2 stoke 250cc (actually like 229c) came with a 38mm carb. Kinda seems too big. The pipe Is a smaller pipe for a 125ccbike. I will be putting on a larger pipe however. So should I stay with the 38mm? It took me a while to get the bike to run without bogging when fast throttling but just not sure if I should go down a size or keep it due to pipe change soon.
2 strokes require a matched pipe for proper operation. Your bike might need crank seals if it is old or worn. Same if this has reed valves or some type of exhaust valve.
Too big of carburetor on a 2 stroke will reduce peak,it won't reach peak rpm,if you have a 100cc 2 stroke with ported intake and exhaust i recommend putting 24-26 mm carburetor,too big of carburetor will have large fuel droplets meaning it will burn slower,smaller carburetor will have more intake velocity making guving a better atomization and wuicker burn rate
So, if I want to put dual carbs on my I4 honda cb750, how do I pick my carbs, Murray dual carb kit has two vm34, but I don't know how much modification was made to the carb. Any tips? Does the size of the 2 carbs need to be bigger to compensate somehow?
Are 24mn flatslide carb almost equal to 26-28mm round slide carb at full throttle opening? Because of the poor Flow in the round slide carbs at full throttle? Faster airflow/velocity in flatslide and chainsaw carbs then round slide carbs? 🧐
@@thejunkman i want the most stable fastest 125 but with cut off's cuz im a sleeper ,,and you might b junkman and killin it but i am the RATMAN i love my mechs trash sooooooo much and im actually ,,,,, making my own oil filter holder A oil circulation slave thingy ??? out of the aulm2 from the starter motor + jbox and my old empi billett filler to make me a -gear slave right on my cshaft like a pump then catch can to get me some eg nox cooling for those baja sunny highway rides AND THEN where my ft# plate WAS witt be my oil cooler with a puller fan in ft like a ve babby moooooooo POWER but my cames b DAF so making another oil in piggot valve to a wg to the oil slave to a temp gauge and a partradge and a pair tree lmfao
No. It would be a good move to properly jet your carburetor. It may only need a cleaning if running on choke makes it better as the main jet could be partially blocked. I have videos and a site page dedicated to all of this. www.thejunkmanadv.com/motorcycle-carburetor-jetting.html
Is it bad idea to replace CV carburetor to a slide one in a 450cc dual cylinder chopper? what are the cons? hard to find a cv one for reasonable price..
Greetings junkman. I just bought a 2 stroke motorcycle. The previous owner told me he has change the cylinder bore and piston from 56mm to 57mm. Is it necessary for me to change the 20mm carburetor to larger carburetor seems the displacement has change from 120cc to 125cc.🤔 Thanks.🙏🏾
I threw a 26mm on my powerfist 208cc (go kart,mini bike, woodchipper engine ect) has a 3 stage header, removed governor, fuel pump normal stuff. The stock carb was maybe a or 20mm or so an man its a huge difference lmao
The more I think about this question the more I realize a lot of people don't understand volumetric efficiency. A big carburetor works good on a big engine. But what happens when you're at a stop / low idle and you go wot. That 1k cc engine at 500 rpm would eventually be the same as a 500cc engine at 1k rpm. It's not pulling very much air. So if it works good on the big engine at low rpm it should work good on a smaller engine also. It just won't utilize all of the carburetors potential.
I need your help please. I installed a two mm larger flat slide pwk oko carb on a ktm 50cc, air cooled, case reed w an 80cc exp. chamber. Being 2 mm larger w a graduated (coned) intake, what jet size, pilot should I use? Im pretty certain the stock jet on the stock 19 mm carb(round slide kehein) was a 105-108. werent marked? I compared to dozens under a mag. glass.
Great teaching. I just added a racing cdi and an Pz22 on a 110cc engine that came with a pz19. It cranks and runs fine. I can’t use the choke though. It cranks fine without the choke and when I engage the choke, the engine immediately dies. Problem is the cable is now too short. But I figure I can decrease cable housing to fix that. And It is leaking fuel through the overflow. Should I just go back to 19mm? I’m brand new to this stuff.
![BEST GY6 PERFORMANCE MOD! [Plug & Play carburetor]](http://i.ytimg.com/vi/snhUWQnFgbE/mqdefault.jpg)
junkman rules!
Holy shit this is a great video. Entertaining, beautifully edited, and informative. Way to step up your game Junkman! 10/10
Thanks. I try to improve something, even if it is small, every time I make a video.
I have a standard 135cc motorcycle using a 25mm carburetor.
I upgraded it to 150cc with some other upgrade such as racing camshaft, high-compression piston, bigger valve, K&N round air filter, leovince exhaust... and I used a 30mm CV carb , it works ok with good performance.
And then I kept the 150cc bore and downgraded to standard camshaft, lower comprestion piston, smaller valve and original exhaust, stock air box filter, but I kept the 30mm CV carb and it didn't work well even though I tried to adjust it. And I replaced the 25mm carburetor and it worked great.
That is some good information. It highlights that internal modifications can have a profound effect on carburetor performance.
Great video!
I have a small 125cc Suzuki (Address 125/FL125/Shogun125, various names in different areas). Since the EFI unit went bad (costs like 300-350 euros to get a new one), I went with the good old way. Converted to carburetor (the Asian version comes with a 18mm Mikuni VM) and used a Keihin PZ 18mm one. Engine had good low-end torque but lacked power on the top-end. Meanwhile, I had literally zero experiance with carburetors. Stupid me, went on to get an OKO PWK26...I tried different jets (32,34,36,37....105,110,115,125...) but still the bike couldn't keep itself idling for more than a minute.
Low-end the engine was like "choking", top end power was good but I felt like it was lacking something. After about 2 weeks of torture with the OKO, I sold it and got a 22mm one. To my surprise the bike runs great! Didn't have to get into jetting, only had to adjust the idle speed a bit. Both low-end and top-end is good and even in cold temperatures, the choke works well so far.
Okay o find this funny I have a 30mm pwk carb on a 50cc! And it runs great it idles better than ever. it rides smooth.
But remember my stock carb was a 17mm carb
You sir have answered a lot of questions I had about upgrading to a bigger carb and informed info's I never knew I needed. Big thanks. Your channel is great.
I just wanna run this f7. Bad 26mm carb missing everything inside. Now i need to dig around and see what carbs i have around here. I know i have a brand new 24mm mikuni. Its too small but atleast now i know ill have tons of low end power to put-put around in the corn field
I guess it all comes down to the idle and max rpm’s mandatory cfm “cubic feet per minute “ of air. And the carburetor must be able to perform at both ends of those requirements. The inability to do so will starve the engine for fuel or flood it with too much fuel in the air to fuel mixture.
Pretty much. It seems most people get caught up in the "bigger is better" trap.
I have a 80cc rieju with an 28mm carb and it runs like a monster
@@booz8313 i can respect that. Currently running a 80cc derbi with a 28mm as well. The thing rips so much you can hear it sucking all the air in. It's crazy b
Hi! Can you explain what carburetor size go in fonction with the cc of the engine for best performance ? Thanks nice video !
There’s no solid formula for the ratio of carb size to capacity especially since multiple different engines of the same cc can use vastly different carb sizes
Maybe u gotta try each size, but thats gonna costs a lil bit
In my case im using 30mm carb on my bike, but the performance only good starting middle rpm to high rpm. Low rpm quite poor performance, it feels heavy.
I need to downgrade to 28mm carb to get good at low rpm. Since im using it for daily. Unless im going for touring, then i would use 30mm back.
@@shinjrock7778 what cc do u have and what main jet did u use?
you have to measure the ports and that determines what size carb you get and the most you can get out of it like it determines the biggest one you can get for your bike
awesome detail! for such a simple thing, carburetors are often viewed as a baffling item.
Yes. And this video is part of a larger series on carburetors in general. I have an entire page on my website dedicated to all information centered around carburetors and tuning.
Wouldn't the throttle slide or plate counter act the carb size though? It meters the airflow
I went from 24mm to 32mm flat slide with upgraded 7mm lift cam. The engine is 200cc single cylinder pushrod type. It runs good. Though sometimes there's a little bog on mid throttle and sometimes the idle is not stable. I'm thinking that it could be a faulty needle. But its true, at high RPM, it runs like a beast, and its a lot of fun. At low RPM, it pulls like a champ as well. Its just that mid throttle and idle that bothers me sometimes.
It you find that lifting off the throttle makes it try to go, its running weak in that area. or rich if you get nothing from lifting.
Mid range, try lifting the needle by lowering the clip if it has one.
Roundslides seem to be easier to tune same diameter i ran a flatslide 30 on my 150 changed it to a nibbi 30mm ran way better for some reason if u run pwks they dont seem to run how u want them on a 4 stroke
@@Saucethe1 to big carb, try a 26 mm for a 150cc engine
Got a 4 valve zs212cc and I got a 500 dollar proper motorbike carby I wanna use ids 33mm how would I make this work on a 28mm/30mm manifold any help be appreciated thank you ??
@@mikga4528mm for me(150cc)is decent but your right a 26mm pwk for 150cc is best.
on my snorkeled 4wheeler i used pvc no air box just a boot i have a ball valve on the stack to change the air flow if it is all the way open it bogs at wot i close it about 1/4 way to tune top end works for me 30 mm carb 230 cc quadrunner
Thx mate, no wonder my bike sucks at low rpm, the fuel is not atomized properly. U helped me solved months problem😂
If the carb is a 30mm and the port or opening in the head is 24mm you create a bunch of turbulence in the flow. you might be able to make the bike run but that trubulence can make it hyper-finky to tune and then you have to get into the other things like cams and valve diameters and exhaust and and and.. but the first step should always be matching the carb to the port.
I’ve got an aprilia rs125 2005 unrestricted 28mm carb and I was thinking if I put a bigger carb it’ll go even faster, but I also want to wheelie in first😂
I got a 229cc with a 28mm carb
I've used 26 and 22mm carbs on 212cc and have had good results with both.
That's awesome & interesting
thank you!!
I was confused about the decision to buy "Mikuni VM Series Carburetors VM26-8074" or "
Mikuni TM Series Carburetors VM28-418" for my Yamaha Rx100 which has an oversize imported piston, but I'm clear now thanks to Junkman for the crisp and easy explanation, I'm going with 26mm.!
I put a 26 mm carburetor on a 125cc lifan engine and did 40 mph also I'm 240 pounds and the engine is on a 50cc taotao frame.
What is your advisable for my 125cc china bike .I'm using 26mm nibbie super sport.my problem is it's good on idle and 1/4 throttle but when I rev up my engine slows down
May 150cc uses 27mm stock. Planning to upgrade 30mm carb. Is it a good upgrade?
I have a brand new 230cc 4stroke dirt bike with a 28mm carb, I cannot seem to eliminate the idle to wide open bog, and it falls on its face type of bog not just a slight hesitation... any ideas? I have tried so many settings and jets with it to no avail?
The problem is the engine design. Those engines have heavy fly wheels and internal parts and just can't react that fast.
What about jettings?
I have a dedicated video for that.
I have a problem with this tool, it's a KTM 250 2T
The tool has not been used for almost a year
This week I found time to take care of it, I did a fuel-oil change, I cleaned the filter plug, everything, finally I tried to start it, but the car could not start.
It only started with carburetor spray and shut off straight away
From that I understood that the carburetor needed to be cleaned and that's how I did it.
Now the problem is different, the motorcycle drives straight up to very, very high turns
I played with the air-fuel screw but unfortunately it didn't help.
Is there a situation where the problem is different? Something in the carburetor maybe? need help please
let me honest with ya
only idiot people put 28mm carb on 57mm blok xD
even my self, only using 26mm carb cause my intake valve was 31mm ex 25mm cause I was concern bout to match intake diaeter with carb diameter size for better engine performance......
cause I be honest with ya, intake diamter on the head, should be less 10 percent thant valve intake size, like was I had, 31mm in valve, so I should use atleast 28 in diameter hole in the head, also match with intake manifold should be in 28mm and also the carb should be 28mm to for stable air flow,
but 28mm carb diameter was 29 mm, so, using 26mm should be enough for had decent airspeed flow through that carb...
I tell this I'am already did this before and it's run fine without any problem like bog or something like that.
and also, try multiple pilot jet and main jet for better throthole response..
cyaaaa
Ive always found sizing weird. My 150cc scooter engine popularly uses a 28mm carb when built up a bit, and yet built predator 212s use a 24mm at full built capacity
Well it sort of works like this. Smaller bore will maintain velocity which is good for low end torque. On the converse larger bore carburetors favor high rpm power. Intake valve size, duration, lobe separate of the camshaft and cylinder head design and volume all play a part in determining optimal carburetor sizing.
@@thejunkman huh.....interesting! I cant wait to see how it wakes up swapping from the 24mm cv to that 28mm slide with a cam and intake 🙏
1977 ford 302,rebuilt,machine to biger pistón, machine heads,i had 2 Barcelona carburator, wat carburator can i put to work well
Your camshaft documentation should give you some guidelines on the size. It will also depend on your intake manifold. Something like a 500-650 cfm should be just right.
Just a question, how to determine which main jet size is to be used on a certain carburetor? For example, what size of main jet should i use for a 27mm carburetor round slide?
Start with what the manual states for your bike. Then test and try other jets up and down until you get it dialed in. I have other videos on that.
How to tune my 33mm flatside carb it's on a 200cc Chinese motor atv?
Put a traditional 28 or 30 mm round slide carb on that motor. They are notoriously undersized in the port, valve and cam specs
So the 33mm carb is to big for the 200cc engine? If so..Wht size jet I need for the 30mm carburetor?
If you measure the slide on the left carburetor,you will notice that the slide will be narrower than the opening going to the engine(around to 20mm). This is the reference i take in mind in order to measure, because the air will always have the speed of the narrowest point on the whole intake. Am i wrong here?
Hi thejunkman. I have a 125cc engine with a 20mm carb. Can I upgrade to a 22mm without doing any internal mods?
You can try, but you will want to port match the intake for sure.
thejunkman. Thanks 👍
I have a twin cylinder Honda CD125 Twin Bike with CB points and a 6V system. My engine is running smoothly and with more pulling power at cold weather, Early in the morning and at night. But when I ride during the day when the atmosphere is hotter then the engine is not running smoothly and the engine power is lower with increased engine noise and engine vibration. When I happen to ride from hot atmosphere into cold atmosphere due to raining on the road immediately the engine is begining to run smoothly with less engine noise, with less engine vibration and increased engine power. I wanted the engine always run smoothly as It was in the early days that bought it. On this matter I had many technicians try their skills on my bike and non of them were so far able to solve my problem and bring the engine back to the performance at early days. I am still wondering what could the reason be. Hope to have an efficient answer and advises to regain my engine performances. Thank you in advance....
well this is akward... i wanted to put 28 mm on 65 cc :D
Question. On a 125 honda cm twin with pod filter and slightly modified exhaust, comes from stock with a 26 mm carb. Would you recommend go higher on main jet or go to a pz30 and decrease main jet size? Thanks
If it feels anemic then yes.
Good morning i rebuilt,a 302,the motor heads,were machine,and i put a 351 cam,do i put a biger carburator,or wat carburator
I built a 2018 honda 250x 4wheeler for my nephew with a high compression piston, opened up exhaust, opened air box and jetted carb. I was surprised to see it came with only a 20mm carb being a 229cc with around 18hp stock. Would I gain anything from a bigger carb?? I can't find an example anywhere of anyone putting a bigger carb on one of these. Seeing that most 125-140cc engines come with a 20-22mm carb and even the 6hp go karts run that or bigger makes me think that these are undersized and maybe I could gain a lot from a 28mm or so?? Any advice would be appreciated!
Most likely yes
I have a klx 143 v1 head it's a trail bike I believe same with the 26mm carb its cold here but I put a bigger jet and dropped the clip to the bottom plug is dark and oily I'm going to get some fatter jets and play around more
If the plug is oily, that is more of a ring or valve guide sealing problem. But you are on the right track with jetting.
I have a Chinese cool strip 125CC and it has PZ19 stock carb on it. Is there any point in putting a 24 or 26 mm carb on it then would I have to get an intake Adapter boot? Do I have the wrong thinking about this whole deal?I just want the bike to idle and run better these carbs I keep buying for For 18 to $30 just don't seem to be doing Right and definitely not very long.
Sounds like you need to just fine tune your jetting. The 19mm is just fine
Can I run anything bigger then a 26mm on my 140cc pit bike if so how much bigger.
Depends if the head will flow that much more. I have a big valve head and high lift cam using a 26mm on my CRF50 with a bbk 140cc. You sacrifice low end grunt for getting out of the whole but the mid is nice and meaty.
i have a 70cc yamaha fs1. is a mikuni 21mm good for it.
I wanted to change my carburator from 150cc stock to 100cc carburator for my scooter due to high gas consumption can anyone guide me if this modification is good
You will have to re-jet for that. You will gain some lower end torque but loose some high rpm power.
Is there a ratio for engine size to carburettor I have a royal Enfield classic 500 which is a long stroke thumper with a 33 mm carb and I have other smaller 200 cc bikes with the same size my plan is to upgrade the 500 to a 42 mm carb with a longer manifold to get better mixing of the gas and adjust the cam timing for rpm will it work or will it stutter midrange I did the same on a custom 200 wher I over bored the engine from 160 cc to 200 it had issues with mixing the fuel past 4000 rmp
It would be nice if it were as simple as Displacement : Carb size, but there are too many factors in that affect what the engine requires as far as carburation is concerned. I may do a future LIVE Q/A and go over this as it is a lengthy explanation that ends with a "it depends". For you it is largely going to be a trial and error process to get a carburetor sizing and jetting dialed in given the modifications you plan to make.
i have 1997 trx300ex big bore 80mm piston/cylinder camshaft stage 1 rebuilt ..... what size carb should i get oem is 32mm ?
I would keep it as is to start and tune it best you can. If it seems a little anemic in the upper RPM's then I would go to about a 35mm.
125 motor
velocity is an easier way to explain it. look at it in CFM efficiency terms.
Very informative unlike other people videos that must smoke 💨 crack 💭 💊👽
Hi. I have recently developed a hobby of putting carburetors on non-carbureted engines. Currently I am running a Honda D15B (1493cc 16 valve) with a VW 30/31 (designed for 8 valve 1600cc). It runs great and I am super proud. However, I am flirting with the idea of creating a dual carb manifold. Do you think would be able to run a 2 VW carbs with only some minor adjustments? I feel like it would either *just work* or I would run into a rich condition. I cant find a guide online, do you have any incite? Thanks :)
Hey, new subscriber here! I also have a 125cc, changed the block/piston to 56mm now its a 135cc, same deal im using a 28mm carb, regrind cams, intake and exhaust ports are ported and polished(which some people said were too big), big valves, free flow exhaust. with all these mods i only gained little power and it is so hard to tune. So Watching ur video convinced me or made me suspect that my carb is too big for my engine. I also heard that bigger intake ports could lower velocity. Do you think reducing the size of the intake ports could increase power or atleast increase velocity of the air fuel flow? Or should I get bigger cams to compensate with the big carb and ports? What are your suggestions?
It depends on what you want to achieve. Re shaping ports is not an amateur job, especially if you are trying to optimize flow characteristics. I would make sure you have a cam that has enough duration and overlap to keep the air moving and fuel atomized.
i just recently did the same thing got a whole new top end bigger piston to a 56mm which stock is 52 on the 125cc same thing i got valves done 7.0 camshaft and a 28 mm carb should be perfect for the bike try getting more performance stuff to help the tunes more like get a different cdi box different coil for the bike that’s what i did helps with better timing and stuff and get all the power you really want in the bike i had got a 30 mm it works but i feel like going down to a 28 it’s way better and should be perfect
thejunkman Thank you for your suggestion brother, ill try installing a bigger cam. Stay safe and have a great day!
@@thejunkman great video brother, do keep up the good work...I have a quick question for you concerning cvk carb vs the slide type , I have a Honda storm 125 cc and I have noticed that ever since I bought it brand new ,the start up is ok but sluggish when accelerating, I've noticed the same thing with guys who have the same type of bike , after research I've found that the diaphragm type carbs are much slower in reaction to the slide type ...my question is is there anything that can be done to improve the throttle lag and also can I swap out the cvk for a mikuni , if so what size do I purchase and what else do for the mikuni to work? Thanks in advance
@@deniscastro2880 problem here in Philippines their is alot of 2 stoke dirt bikes running around in 125cc and the 28mm works ok with reeds, not so with 4 stokes.
Boo to the 32 dislikes! This guys great got my like!
i dont really know a lot about this but if you have a big carb, why wouldn't it idle well? at idle, the air goes through the idle circuit instead of the venturi right? so how does it impact the idle?
The venturi does still play a factor as well as the pilot circuit design/size. However its the off idle performance that could suffer if too drastic of a size change is used.
I have a superstomp 125 (chinese), completely stock. It bogs down in high revs but iv checked the carb and the jets are squeeky clean. Iv heard the stock carbs on chinese pit bikes are trash so maybe could do with being upgraded. What size carb would be best. I heard you say 24mm in the video. Great video btw and thank you.
Your carb is fine, it just needs to be richer on the 3/4-full throttle. You need to see my jetting videos. This is fixable. Stock Chinese carbs are jetted kinda lean for importation purposes.
Thanks man i will give it a watch!
Probably getting too much fuel
Is UMA RACING 28mm carb good for a SUZUKI EN125-2A(125CC ENGINE) upgraded with SUZUKI DR150 cylinder kit?
Hey can i put a 200cg carburetor on my 150cg motorcycle
Me staring at the thumbnail before I clicked on this video thinking this makes no godamn sense
Hello sir for 80cc can I put 28 carb? No has 26
I have 1 motorcycle 2 stroke at the same time my standard bore stroke are 57mmX54mm.my question,what size bore or piston i need to use carburetor size 58mm for dragrace?
the stock carburetor will be fine, just re-jet as necessary. However if you have a CV type a change to a piston or mechanical slide type would be preferable. See my other videos on that. th-cam.com/video/i6yOd2lwwDU/w-d-xo.html&t
My yx 140cc with z40 racing cam rips with a NIBBI 22mm carb
Hello what would be your recomendation on a 150cc with a full system on also Racing CDI, Coils and spark plug and a couple more mods, I’m trying to reach the maximum performance out of it.
I’m looking between a Nibbi PWK26mm or PWK28mm which one should you recommend?
My stock carburetor it’s a Pz27 which measures 27mm on the cylinder side!
Thanks a lot sir I would really really appreciate your thoughts on this matters since I’m new to it
Chainsaw...Zombies....every gamers thoughts, always.
His engine is 147cc because he upraded to 57 bigbore
Polish subtitles please
Ok I got to ask what happens if u put a xt500 carburetor on a Honda xl 250 r?
It will probably be hard to tune, but it would probably work.
@@thejunkman oh ok but the xt500 carburetor is already tuned but it will just ideal to high but u get turn the idealing screw down. Right?
You will have to adjust/tune it for the smaller and higher velocity intake of the XL250
Please respond!!! I don't want to blow up my engine again I have a 96 Polaris XLT special with a 580 monoblock comes with 38 mm mikuni's the sled I am currently building had 34 mm mikuni's I took the 38s and put them on the sled I'm riding that had 34s is this going to be okay the other day I blew up the original engine that had the 34s on it had to pull another engine from a different sled out back that had 34s on it that's the one I put the 38s on sorry about the long comment but I don't want to seize another engine this one has awesome compression
There are more factors than carburation at play when an engine seizes. So that might have not been the issue. If you are worried start off with a bit richer fuel mixture, test, then fine tune the jetting leaner doing plug inspections regularly. And if that sled uses oil injection be sure the system is blead properly.
I have a 200cc scooter that I changed the carburetor to a 30mm and it'll start,idle,and drive in the low rpms but past about quarter throttle it bogs down and starts popping..... Any suggestions on the jetting or adjustments that I can make to get those about quarter throttle rpms???
Check out mvideo all about it. Or my website. Links in the description.
Is that a sp250 in the picture on the wall?
Kawasaki F11, take a look again.
@@thejunkman sure enough! Awsome video and thanks for the comment!
Hi Junkman, I have a 77 KE 175 cant find an expansion chamber for that year. Will a 1980 KE chamber work even though its tuned to a reed valve engine?
It will probably work from a design standpoint, however it probably will not bolt up being the mounting points and cylinder port is in a different place so the bends won't make it physically fit.
Sooooo basically just get a bigger carburetor and turbo 😂😂💀
Hi Junkman. I have a project bike a 78 dt400. It has a 34mm round slide. I would like to try a 36 mm flat slide carb. I was wondering if for a given size round slide vs. flat side mikuni carb is the float tower talker in the flat slide. I have limited clearance above my stock 34mm round slide as the pipe crosses above it.
Flat slides are usually taller in general, but you could try it.
Cool video, so what if you had say a Keihin Pb18 and the Mikuni equivalent.....they would still have slightly different attributes? Like more adjustability of each circuit?
Yes, the design will make a bit of a difference.
Bigger carb
Ported heads
Performance exhaust
Do u think a xtz 125 with a 26mm would run with a 36mm with a aftermarket slip on
Probably not
Great video! I wondered if you could help.. I'm fitting a Rotax 257 single; 2 Stroke (kart engine) to a bike; any ideas what size Carb i should be looking for for optimum mid/high rev range? i think* stock was a mikuni 38mm carb but not 100%. Any advice would be amazing! Steve
If you don't care anout idle quality then put a 42mm PWK on it an dial it in.
I have A 150Cc China Bike,Will It Run Normally If I Put 125Cc Carburetor? All Can Advise Me,Thanks
No, you will have to re-jet. You may loose some top end power for a gain of lower end torque.
What is symptom of too big of carburator? Hard starting? I have a tpr 86cc 2 stroke with 30mm flat pwk polini with vforce3 reeda on a yamaha zuma. It is alwyas hard to cold start it. Once it started, starting is no problem,idle is perfect, it rips too on all throttle range..
It is just the starting that i am having trouble with. It basically floods my exhaust maybe around 10kicks with 1/2 throttle before it even start. Choke doesnt do nothing. I have highher chance of starting it with pulled throttle up to 1/2.
Thanks!!
What if I put two carburetor and modify one of them to operate higher RPM.
It doesn't really work that way. Honda tried it for 2 years in the 80's with their XR350 and it didn't work well and was a nightmare to make run right.
Far too much
"woffle" ! ...... get to the point !
Hey me I got a 2 stroke blaster I cleaned the original carb still over flowed ajusted the needle still over flowed bought a new stock crab put it on and same thing it over flowed I don’t know what to do at this point and all the shops around me are booth
Did you check the float height?
question, i know its odd that a certified master mechanic should know this, but i was given a nibbi racing 24mm output dia with a larger 35mm intake dia as my OEM carb.
oem carb is a 33 input, 30 output.
nibbi is a 35 input, 24 output.
id assume that this carb would lack airflow if i were to boot it to my 250cc 4 stroke's intake.
I dont want to lean my engine, I'm okay with a small loss of power, shes an in town putt-round anyway, but more low throttle power is desireable.
ive never asked the question, cam i down size my carb and not suffer too many losses, maybe even experience some gains in fuel economy.
Pffff ! You only spoke trash. From experience I can tell you ,that a 21mm can be replaced with a 28 mm with no problem ! Whatever youve said it is just to superficial.
That is excellent news! I am glad it worked out well. That's what its all about.
@@thejunkman just tune everything correctly in it ,and it will work like a dream.
I love the t shirt. Thanks for the video. I have a paramotor (basically a chainsaw engine. I realised I had tuned the carb with a spacer missing between the carb and engine. It ran well but when I replaced the spacer (only around 10mm thick effectively pulling the carb further from the engine) it leaned out. Fuel air mix had not changed at all but it leaned out so much it would not run anything other than tick over. Any idea why this would happen ?
You will like a engine with the right carburetor much better than a engine with a large carburetor! It's not going to be that noticable, if you can't enjoy the ride to the high rpm! Basically 2mm larger for more power, 4mm larger if you big bore and cam, port the head, and air filter, and free flowing exhaust, to get more flow for the 4mm larger carb, a 50 cc engine I been working with I went from 39mm bore to 50mm, with a head with larger valves, from 16/18mm, to 18/21mm, with ported head, cam. Exhaust, and from 19mm to 20 mm carb, it still has lots of low end throttle response, but stock type CV carbs are not that available, they come in 18,19, and 20, then 24,28,mm. The 24mm is too much, it idles, but will not rev, it can't pick up enough fuel, too much air, and would be alot of work to get it to run crappy, ( the 24mm is for 125-150 cc in this family of engine) most 150-170 use a 26-28mm,
I did find a Yamaha, CV carb that I modified to fit. It is 22mm, it should work, maybe with some further mods, jets and tuning, but I think I'll save it for my 52.4mm bore kit, getting closer to 100cc, being the carb is for a 125cc Yamaha, my engine does spin a bit higher than the stock version peaking at 8500, I have seen 10300 rpm, I try to keep it below 9500-9800, the stock carb didn't want to rev past 9k, great video, it explains things well,
Just saw your vid. My question is the bike I juts got, 2 stoke 250cc (actually like 229c) came with a 38mm carb. Kinda seems too big. The pipe Is a smaller pipe for a 125ccbike. I will be putting on a larger pipe however. So should I stay with the 38mm? It took me a while to get the bike to run without bogging when fast throttling but just not sure if I should go down a size or keep it due to pipe change soon.
2 strokes require a matched pipe for proper operation. Your bike might need crank seals if it is old or worn. Same if this has reed valves or some type of exhaust valve.
Too big of carburetor on a 2 stroke will reduce peak,it won't reach peak rpm,if you have a 100cc 2 stroke with ported intake and exhaust i recommend putting 24-26 mm carburetor,too big of carburetor will have large fuel droplets meaning it will burn slower,smaller carburetor will have more intake velocity making guving a better atomization and wuicker burn rate
The cut away to this mad lad with a chainsaw❤😂
So, if I want to put dual carbs on my I4 honda cb750, how do I pick my carbs, Murray dual carb kit has two vm34, but I don't know how much modification was made to the carb. Any tips?
Does the size of the 2 carbs need to be bigger to compensate somehow?
Are 24mn flatslide carb almost equal to 26-28mm round slide carb at full throttle opening? Because of the poor Flow in the round slide carbs at full throttle? Faster airflow/velocity in flatslide and chainsaw carbs then round slide carbs? 🧐
what if im doing it all???????? picture looking through a shotgun barrel and do the same FROM 10 GAUGE TO 12???????
So you want to go smaller?
??????? clean tunnel like a butterfly
@@thejunkman i want the most stable fastest 125 but with cut off's cuz im a sleeper ,,and you might b junkman and killin it but i am the RATMAN i love my mechs trash sooooooo much and im actually ,,,,, making my own oil filter holder A oil circulation slave thingy ??? out of the aulm2 from the starter motor + jbox and my old empi billett filler to make me a -gear slave right on my cshaft like a pump then catch can to get me some eg nox cooling for those baja sunny highway rides AND THEN where my ft# plate WAS witt be my oil cooler with a puller fan in ft like a ve babby moooooooo POWER but my cames b DAF so making another oil in piggot valve to a wg to the oil slave to a temp gauge and a partradge and a pair tree lmfao
My bike runs lean/ needs choke in low gears. Would it be a good move to upgrade?
No. It would be a good move to properly jet your carburetor. It may only need a cleaning if running on choke makes it better as the main jet could be partially blocked. I have videos and a site page dedicated to all of this. www.thejunkmanadv.com/motorcycle-carburetor-jetting.html
You’ve explained it in a way I never would of understood so simple thankyou I don’t know why everyone makes it so difficult 😅
My bike is 250 cc and i increased the engine comprision.. can i use 28 mm carb?
I have a 250 single cylinder 4 stroke which comes standard with 28mm. I have upgraded to 30mm and it increased performance.
What maximum size carburetors can be use for a 200cc motorcycle?
It depends on the engine type and configuration. 38mm is getting to the limit.
Is it bad idea to replace CV carburetor to a slide one in a 450cc dual cylinder chopper? what are the cons? hard to find a cv one for reasonable price..
Greetings junkman. I just bought a 2 stroke motorcycle. The previous owner told me he has change the cylinder bore and piston from 56mm to 57mm. Is it necessary for me to change the 20mm carburetor to larger carburetor seems the displacement has change from 120cc to 125cc.🤔
Thanks.🙏🏾
You cat put single or individual carburator same size opening in 4 cylinder bike?
Depends. You'll need a manifold to accommodate it.
I threw a 26mm on my powerfist 208cc (go kart,mini bike, woodchipper engine ect) has a 3 stage header, removed governor, fuel pump normal stuff. The stock carb was maybe a or 20mm or so an man its a huge difference lmao
The more I think about this question the more I realize a lot of people don't understand volumetric efficiency. A big carburetor works good on a big engine. But what happens when you're at a stop / low idle and you go wot. That 1k cc engine at 500 rpm would eventually be the same as a 500cc engine at 1k rpm. It's not pulling very much air. So if it works good on the big engine at low rpm it should work good on a smaller engine also. It just won't utilize all of the carburetors potential.
I need your help please. I installed a two mm larger flat slide pwk oko carb on a ktm 50cc, air cooled, case reed w an 80cc exp. chamber. Being 2 mm larger w a graduated (coned) intake, what jet size, pilot should I use? Im pretty certain the stock jet on the stock 19 mm carb(round slide kehein) was a 105-108. werent marked? I compared to dozens under a mag. glass.
You will have to test. Try the stock and see if it runs, then go up from their.
Great teaching.
I just added a racing cdi and an Pz22 on a 110cc engine that came with a pz19. It cranks and runs fine. I can’t use the choke though. It cranks fine without the choke and when I engage the choke, the engine immediately dies. Problem is the cable is now too short. But I figure I can decrease cable housing to fix that. And It is leaking fuel through the overflow.
Should I just go back to 19mm?
I’m brand new to this stuff.
adjust the float needle