You are literally the only person that makes sense on this topic, I have a crf150r and I had problems with bog and I tried everything. Just until I found this, I tried and it my bike runs 110% better. Thank you dude. Really thank you
You made my day awesome today. First YT video i opened. Answered my question instantly. THANK YOU SIR. Coz i just bought an old YZ250 ‘06. My very first dirtbike. My 11yo race on his 65cc ktm. 3 yrs now, I fast paced learn how to fix and maintain this lil ripper. I dont have a deep pocket, so we have to rely on diy. Now i got me a dirtbike so i dont have to watch him ride anymore. I tore down this yz already twice, to clean and learn the bike inside out. I noticed this o-ring wrap around that accl pump adjuster. And YOU sir just gave the answer. THANK YOU VERY MUCH FOR THE DETAILED EXPLANATIONS in regards to this part of the carb. Your lessons are priceless. Buying you a dozen of beerz still priceless. Have a great day.
Thank you! I had the o-ring on but I jumped to a QuickShot, JD kit and different jets, trying to get the bog worked out. After watching your video, turns out that screw was so far out, I was only getting 1/2 a shot of fuel. I adjusted that and got immediate results. The QS, JD and jets did absolutely nothing when I adjusted them. I have a Rekluse auto-clutch and the bike is idling low. I turned up the idle and that contributed to it being much snappier as well. I believe a Rekluse can magnify the bog problem. Thanks for taking time to post this.
Thanks Matt. My 2004 wr250f has always had a terrible bog in the throttle. After watching your video and following your steps and adding the o-ring it has made a huge difference!!!!
Yes! I was about to ask, what happens if I set up the carb as shown in this video, but my idle is not setup.... I have carb off the bike atm... This was super informative! Many thanks for sharing this!
I was having crazy bad bogging issues on my 11 ktm 530. Managed to adjust the slop out of the ap using the adjustment screw. Had to look carefully at where the rod that presses the diaphragm sits in the black plastic arm. You can see the slop and find where it is no longer pressing the rod down at all. Absolutely rips now no bog from idle while riding. I am also using the thick o ring from the JD jet kit. Worked great for me without removing the carb from the bike. Only the seat and gas tank.
I did this with an 06 crf250r I bought for nothing , none one could get rid of the bog . worked 100percent . bog gone runs like a beauty , great video thanks .
Thank you so much for this. AP pump timing has always been gypsy magic to me and I've been living with the Honda bog for ages. No one really has a good video of this until now so thank you lol
@@HTMR Hi Matt. What if you have inline 4 carbs and carbs 2, 3, and 4 squirt gas when you actuate throttle, but carb 1 doesn't? Keihein carbs on an 82 honda 650 nighthawk. Issue with accelerator pump? Or perhaps a clog somewhere?
Thanks for great video! One question, you say squirt time should be 0.8-1 sec, but in you video it's about 0.4 when you say it looks good, so what should I aim for?
I recently bought an 05 crf 250r, hard to start as well, but runs good, checked valves, they're in spec, spark plug and air filter look good, next is re-jetting, and I suppose I'll check my accelerator pump as well...Didnt know that could be out of adjustment...(my first dirtbike) wish me luck...
@@John_Doe_6996 good luck! just an fyi now that mine is broken in, i had to do another valve adjustment. everything has to be perfect on these motors for them to start easy appearantly. but at least they'll run forever haha! p.s. try a smooth kick from top dead center instead of giving it all you got. seems to like that better
I'm having to remove my carb to find out why my plastic black idol screw won't turn and while it's off in definitely going to be looking at and doing it if it's not already set up. Thank you
This is a commonly overlooked thing on a modern 4-stroke mx bike with the Keihin FCR-MX Carb. Pretty much all common bike brands use a version of this carb if it's a 4-stroke high performance bike. Very easy thing to check and will minimize if not eliminate any off-idle hesitation or bog. Highly recommend ALL of you to do this inspection. (this as well as clean your dang carb every once in a while - and inspect your pilot jet for blockage - AND never never never use standard ethanol-based pump gas. (Because it can clog your pilot jet over time.)
@@bikersoncall If you're somewhere that doesn't sell non-ethanol fuel, your best bet is VP T4 Fuel. It's 97 octane ethanol-free fuel for stock or slightly modified engines. It's expensive as hell at $110 for 5gal but it's an option if you really don't want corn in your bike.
Wish my Mikuni TM33 had some apump adjustments on it. Quick opening the throttle like you did has a stutter, and then acceleration kicks in. I'll have to look it over.
Just cleaned one of these, for my kx250f. Complete teardown and ultrasonic cleaning. Everything seems good but I have alot of backfire win I get into 3/4 -full throttle and let off. Is that my main jet to big or is it float bowl level. Had a hard time adjusting the float.
FROM DA BIG ISLAND THANK U SO MUCH YOUR VIDEO HELPED ME SOLVE MY PROBLEM I HAVE A 05YZ250F AND WAS REALLY WAS HAVING A REALLY BAD BOG NOW BIKE IS MINT GOD BLESS AND MAHALO AGAIN😉😎🍒🤙
Very clear instructional video thanks. I'm looking to upgrade my z400 stock carb that's jetted to a fcr style currently running a 170 main and 75 low jets with a Yoshi pipe and stainless header she does good now but I want little more for the hole shot
For best results, you should be performing this with the slide lifted 0.8mm. I use an appropriately sized bbq skewer to hold it open while performing the backlash adjustment.
I've read that in the manual. I guess they are assuming that if the idle screw is not adjusted to where it needs to be (lifting the slide) then you need to lift with rod. At the end of the day, you want minimal clearance/backlash for a quick shot.
I have a 06 trx450er with stage 2 hotcams,stock Ferrea Valves,100mm Athena Cylinder with CP Carillo piston and full Barkers exhaust,stock air filter no lid,the acc pump screw was moved around, so I'd like to ask your opinion on jetting and timing screw? Sea level is 105' thanks and great video brother!!!!
I can't recommend specific jets, as I never jetted your combo. First, start by tuning your pilot jet fuel screw per this video: howtomotorcyclerepair.com/how-to-4-stroke-mx-fuel-screw-adjustment-yzf-crf-kxf-rmz-fcr/
This is a great video and I love watching your expertise. I have a 07 yz250f and as soon as I did the o-ring mod it started bogging badly. I took the carb off and my ap arm has no slop in it without the throttle cable rigged up whether it's screwed all the way in or not. Should I just set the timing after it has the tension from the throttle cables?
Okey so i've done what you did in this video (back in september). I setup the squirt just perfect with just a tiny bit of play. Still my bike bogs when i go full throttle on low rpm. I saw that the idle/pilot jet was slightly damaged tho, On the top were you screw it. It's like a crack. It is btw a idle/pilot jet 45 (Original). Should i buy a new 45 or should i go higher? The next option that i have from 45 is 48. Btw it is a KTM 525sx from 2004. So it is the exact same carb.
Awesome video man! I am restoring a 02 DRZ 400e with the slant style FCR. Unfortunately this carb does not provide a screw to adust AP timing. However, there is a U shaped piece of metal that can be bent to adjust the AP lever up and down. I watched the video multiple times and adjusted the pump even more but i cant quite get it perfect. How can this be transferred to the slant carb?
Thanks for the video, helps a lot. I have a Husqvarna SM610 (600cc) and my carb is Keihin FCR MX 41. Do you know if I change the OEM leak jet for the 45 size that you mentioned , it will works for me???
This is hands down the best video on getting the accelerator pump tweaked for maximum performance. Getting that “play” - “slop” is the key! And the Oring is a must. I would also recommend the shorter post diaphragm and smaller leak jet. My crf250r acts like it’s fuel injected.
The kits are available at CRF Only website along with instructions. I prematurely ruined the original on my Accelerator pump with carb cleaner😏. Found the CRF Only kits to be a good buy. I’ve picked up two over the years.
This video helped me a lot thank you. I have the accelerator pump dialed in; however, I still notice a slight bog here and there when just cracking the throttle... and sometimes a hanging idle. Would you suspect a pilot jet being too lean?
I tried finding a #78 o-ring and for some reason danco uses weird numbers. For those of you looking a #108 o-ring is the number most manufacturers use it's 1/4 i.d. 3/32 cross section 7/16 o.d. do you know if you can use a #202? Which would be 1/4" I.d. 1/8" cross section 1/2" o.d. if it fits it should last longer?
Great vid. Having a hard time figuring out a lean condition and decel popping on my crf 450x. Have to turn the fuel screw out more than 2.5 turns to make it run right without popping exaust or glowing header pipe. Pilot jet is a 60, main jet is a 175. Air box has been opened up and has a fmf pipe. Any advice on what to do to tune it so I can run the fuel screw 1.5 to 2 turns out without the exaust decel popping is welcomed.
You need to richen up the pilot jet. However you already are at a 60??? That is pretty big. Check for vacuum leaks and make sure hot start plunger is clean and operational.
sorry for the late post, great video, crf450x ap pump its working ok but squirt duration is too short, i have the o ring mod and the squirt timing is fine. how to improve squirt duration? bike bog on wot and then recover really hard.
nice vid, i appreciate.i like it how you keep it simple and load it with info,you know other channels all seem scripted and have same old info repeated and sometimes more about the presenter.could you know a thing or two or anything about stators?especially winding lighting coil on to stock stator of a dirtbike?
THANK YOU SO FUCKIN MUCH!!!! this is a ****** MASTERPIECE!!!! i tried almost every place on earth to calibrate my accelerator pump but nowhere was this clear as this vid!!! MAD PROPS TO YOU MATE!
everytime i squirt gas from that little nozle a get a very thin streak and doesnt seem powerful, ive chained the leak jet to a #35 and rejetted my main jet and pilot anf still does the same, what could the issue be? i have a bad bog (just like yours before the acc pump adjustment)
Awesome vid! You sure have helped me understand. I seem to be having to much squirt. Was looking at the Boysen Quick Shot 3 accelerator pump cover with adjustable leak valve. Would you recommend? Thanks
@@Doctors101 I would just install a 45 leak and oring. Total cost $10. Also make sure fuel screw and pilot jet are setup and you will have a bike that runs mint and save some money. Usually I install 1 larger size on pilot jet to net me 2.5 out on fuel screw.
Great video.. and i have a question regarding the tps. People say that disconnecting tps will reduce the throttle response and bike bogs but if i disconnect the tps and still setup the AP like you did will the bike still lack throttle response or there will be no any issues whatsoever with tps disconnected and AP working as it should. Please help me out.
MatthewMCRepair thanks for replying. But the thing is i am installing this carb in a bike that has no tps connection provided and it actually have a stock carb which also doesnot have tps. It uses mikuni tm 34 style carburetor so i am upgrading it to a carb with an accelerator pump in it.
Adjustable fuel air mixture screw for an FCR39 on a DRZ400. Is there one that will work in the very small void between the carb and the starter motor. I tried the flexible one but it doesn’t like to turn or adjust under the load of the bend. Is there a nurled finger adjusted mixture screw?
@@amandagregg2195 take the black plastic cover of that is on the right side of the carb. And then just turn the adjuster screw to when there is almost no play in the arm. ( the guy in the vid made it more clear then i can do, sorry😅)
Well I went to adjust this, and I couldn't replicate the play you showed so I got confused. Then I realized that the AP isn't squirting at all... Sweet
@@jarredscott2646 soaked in gas, then soapy water, no luck still. Tried squirting carb cleaner through the passage. In the end what worked was pushing fishing line through the passage and moving the check valve back and forth with cleaner in it
There is a "green" acceleration pump spring available, from KTM. It is from the SXS Parts catalogue. If I mind correctly, it is a stiffer spring, what enhances the volume of the squirt. What do you think about it? I can´t really find any informations about this, or reviews. Thank you for the good video!
when we have the problem of the engine speed remaining high even after releasing the accelerator, does it have something to do with the adjustment you made?
Very informative, any tips on what would cause a ktm 250 sxf with the fcr carb to be impossible to start after stalling it on the trails? It will hot start no problem if you shut the bike off with the kill switch, but won’t start or kick over after my kid stalls it on a log of root.
MatthewMCRepair no it doesn’t, but I’m wondering if I’m kicking it wrong by twisting the throttle when trying to start it after it’s been stalled and over fueling it. My personal bike is a 300 2 stroke so I’m way more familiar with those style carbs that don’t pump fuel when the throttle is twisted. I am going to install a JD jet kit in the fcr carb and hope it’ll start a little easier.
Hey man, love the videos, you just do an excelente job, I have a little issue with my new FCR33 carb, it idles good and when i accelerate from bottom to top (on neutral) it seems good, but when i go to ride, it stumbles at mid rpms (half throttle), it goes like ta...tatata...tata..tata..., Then I keep accelerating at full throttle and the stumble disappears, and runs ok on top of acceleration. I changed the needles and it keeps stumbling at mid acceleration. It only happens when I go to ride, but not on neutral. Please i'll appreciate your comments.
Great video. I went to go double check my 05 wr450f’s ac pump only to find out it wasnt even squirting at all. The smaller o-ring under the ac pump cover was totally flattened to the point where the hole was pin sized. Also the brass nozzle it squirts out of was clogged. I un-clogged it all bought an all balls rebuild kit and now it squirts just like this video. Cant wait to try it now and see the throttle response difference. It barely even bogged before also
Thanks for the good explanation about how it all works. And thanks for your videos! You are a good explainer. Hope it’s ok I ask a question? I am reasonably new in 4 strokes! I have followed your advice to set the keihin fcr carburettor on my KTM 250 sxf. When my Fuel mix screw is 3 times out, the engine really goes smooth and throttle responding really quickly. But it is very difficult to start. When the engine is hot, it is impossible even with hot start activated. When I turn the screw a half turn in again, its starting right away even hot. But it doesn't sound that crisp and smooth. Don't you think I'm going to size up my pilot jet? Right now I'm running 175 main and 40 pilot, needle in 5th clip. Only change on the bike is a DOMA exhaust and o-ring mod on accelerator pump. Thanks in advance
I have a small bog issue on a ktm 660 lc4 with the fcr-mx carburator. The bike just bogs down for a very small moment when I give throttle fast. The bike works fine but it is verry anoying. It just feels like it hessitates for a momet at first but it works fine after that. Could it be a worn out accpump membrane? the bike is 11yrs old and has been standing for a while. I really like your videos its good help when trying to learn about carburators!
MatthewMCRepair its not really a bog its just a slight hesitation. it makes it dificult to slide around a bend and wheelie the bike. its like a small delay when i open the throttle fast.
![FCR Carb Accelerator Pump Tuning [EXPLAINED]](/img/n.gif)
probably one of the most informative and easy to understand creators I have watched
This was very, very good. Taking the time to show over, under, and well adjusted, both from the mechanic's point of view and in action, is gold.
Thanks Kyle!
You are literally the only person that makes sense on this topic, I have a crf150r and I had problems with bog and I tried everything. Just until I found this, I tried and it my bike runs 110% better. Thank you dude. Really thank you
Glad it helped.
You made my day awesome today. First YT video i opened. Answered my question instantly. THANK YOU SIR. Coz i just bought an old YZ250 ‘06. My very first dirtbike. My 11yo race on his 65cc ktm. 3 yrs now, I fast paced learn how to fix and maintain this lil ripper. I dont have a deep pocket, so we have to rely on diy.
Now i got me a dirtbike so i dont have to watch him ride anymore.
I tore down this yz already twice, to clean and learn the bike inside out. I noticed this o-ring wrap around that accl pump adjuster. And YOU sir just gave the answer. THANK YOU VERY MUCH FOR THE DETAILED EXPLANATIONS in regards to this part of the carb. Your lessons are priceless. Buying you a dozen of beerz still priceless. Have a great day.
Thank you! I had the o-ring on but I jumped to a QuickShot, JD kit and different jets, trying to get the bog worked out. After watching your video, turns out that screw was so far out, I was only getting 1/2 a shot of fuel. I adjusted that and got immediate results. The QS, JD and jets did absolutely nothing when I adjusted them. I have a Rekluse auto-clutch and the bike is idling low. I turned up the idle and that contributed to it being much snappier as well. I believe a Rekluse can magnify the bog problem. Thanks for taking time to post this.
Your welcome!
Y a auto clutch man u yankys man its all in the clutch mate trust me i rekon its cheating definatly in enduro clutch for me on anything car n bike
Thanks Matt.
My 2004 wr250f has always had a terrible bog in the throttle. After watching your video and following your steps and adding the o-ring it has made a huge difference!!!!
No problem. If you are looking for an even bigger difference, throw a smaller leak in there.
Yes! I was about to ask, what happens if I set up the carb as shown in this video, but my idle is not setup.... I have carb off the bike atm...
This was super informative! Many thanks for sharing this!
I was having crazy bad bogging issues on my 11 ktm 530. Managed to adjust the slop out of the ap using the adjustment screw. Had to look carefully at where the rod that presses the diaphragm sits in the black plastic arm. You can see the slop and find where it is no longer pressing the rod down at all. Absolutely rips now no bog from idle while riding. I am also using the thick o ring from the JD jet kit. Worked great for me without removing the carb from the bike. Only the seat and gas tank.
You are the man, between this video and the fuel screw video I was able to dial in both my 450r and my wife's 150r. THANK YOU!
No prob!
Two years later and you are still helping motorcycles, my scooter now accelerates a bit better thanks to you haha cheers
I did this with an 06 crf250r I bought for nothing , none one could get rid of the bog . worked 100percent . bog gone runs like a beauty , great video thanks .
Bro I was fighting my 05 yfz for hours before watching this video. You are the man thank you so damn much.
My old Husaberg FE450 liked this.
Im doing this on my gf's husaberg right now😇
@@myran_moto330 y
You deserve an award for humanitarian aid. Thanks again
Thank you so much for this. AP pump timing has always been gypsy magic to me and I've been living with the Honda bog for ages. No one really has a good video of this until now so thank you lol
No problem. I hope I simplified how to set it up.
@@HTMR Hi Matt. What if you have inline 4 carbs and carbs 2, 3, and 4 squirt gas when you actuate throttle, but carb 1 doesn't? Keihein carbs on an 82 honda 650 nighthawk. Issue with accelerator pump? Or perhaps a clog somewhere?
@@jrich240h Nozzle is probably clogged.
Thanks for great video! One question, you say squirt time should be 0.8-1 sec, but in you video it's about 0.4 when you say it looks good, so what should I aim for?
This is a perfect instructional video for setting up the Keihin AP. Thank you!
Thanks man, I'm a novice to carburetors and that was well explained.
Ur the only one who helped me
thank you! i just rebuilt a crf250 and this was the one thing keeping it from starting properly. went from 50 kicks to 1 with one small adjustment!
I recently bought an 05 crf 250r, hard to start as well, but runs good, checked valves, they're in spec, spark plug and air filter look good, next is re-jetting, and I suppose I'll check my accelerator pump as well...Didnt know that could be out of adjustment...(my first dirtbike) wish me luck...
@@John_Doe_6996 good luck! just an fyi now that mine is broken in, i had to do another valve adjustment. everything has to be perfect on these motors for them to start easy appearantly. but at least they'll run forever haha! p.s. try a smooth kick from top dead center instead of giving it all you got. seems to like that better
What size main jet and pilot jet would u recomend? Great video thank u!
Just want to say thanks for these awesome instructional videos I appreciate your work 🙏
I'm having to remove my carb to find out why my plastic black idol screw won't turn and while it's off in definitely going to be looking at and doing it if it's not already set up. Thank you
This is a commonly overlooked thing on a modern 4-stroke mx bike with the Keihin FCR-MX Carb. Pretty much all common bike brands use a version of this carb if it's a 4-stroke high performance bike. Very easy thing to check and will minimize if not eliminate any off-idle hesitation or bog. Highly recommend ALL of you to do this inspection. (this as well as clean your dang carb every once in a while - and inspect your pilot jet for blockage - AND never never never use standard ethanol-based pump gas. (Because it can clog your pilot jet over time.)
Where do you get non ethanol fuel?
@@bikersoncall yeah exactly that's the problem 😂
@@bikersoncall If you're somewhere that doesn't sell non-ethanol fuel, your best bet is VP T4 Fuel. It's 97 octane ethanol-free fuel for stock or slightly modified engines. It's expensive as hell at $110 for 5gal but it's an option if you really don't want corn in your bike.
Thanks man. I definitely learned a lot on these types of carburetors. Since i was used to bikes with no AP's Thumbs up man
My guy. You saved me and this headache. Thank you for the great video.
Wish my Mikuni TM33 had some apump adjustments on it. Quick opening the throttle like you did has a stutter, and then acceleration kicks in. I'll have to look it over.
Just cleaned one of these, for my kx250f. Complete teardown and ultrasonic cleaning. Everything seems good but I have alot of backfire win I get into 3/4 -full throttle and let off. Is that my main jet to big or is it float bowl level. Had a hard time adjusting the float.
When you let off, you are back on the pilot circuit. Tune your pilot jet and fuel screw per this video: th-cam.com/video/kUw41sUQbTY/w-d-xo.html
FROM DA BIG ISLAND THANK U SO MUCH YOUR VIDEO HELPED ME SOLVE MY PROBLEM I HAVE A 05YZ250F AND WAS REALLY WAS HAVING A REALLY BAD BOG NOW BIKE IS MINT GOD BLESS AND MAHALO AGAIN😉😎🍒🤙
This is an awesome video! The temp fuel setup to show the fuel delivery difference is great. Thank you.
Thanks a lot mate, you deserve a billion likes.
Thanks!
Very clear instructional video thanks. I'm looking to upgrade my z400 stock carb that's jetted to a fcr style currently running a 170 main and 75 low jets with a Yoshi pipe and stainless header she does good now but I want little more for the hole shot
For best results, you should be performing this with the slide lifted 0.8mm. I use an appropriately sized bbq skewer to hold it open while performing the backlash adjustment.
I've read that in the manual. I guess they are assuming that if the idle screw is not adjusted to where it needs to be (lifting the slide) then you need to lift with rod. At the end of the day, you want minimal clearance/backlash for a quick shot.
I have a 06 trx450er with stage 2 hotcams,stock Ferrea Valves,100mm Athena Cylinder with CP Carillo piston and full Barkers exhaust,stock air filter no lid,the acc pump screw was moved around, so I'd like to ask your opinion on jetting and timing screw? Sea level is 105' thanks and great video brother!!!!
I can't recommend specific jets, as I never jetted your combo. First, start by tuning your pilot jet fuel screw per this video: howtomotorcyclerepair.com/how-to-4-stroke-mx-fuel-screw-adjustment-yzf-crf-kxf-rmz-fcr/
Thank u. My Wr400f is happier now. And so am I
This is a great video and I love watching your expertise. I have a 07 yz250f and as soon as I did the o-ring mod it started bogging badly. I took the carb off and my ap arm has no slop in it without the throttle cable rigged up whether it's screwed all the way in or not. Should I just set the timing after it has the tension from the throttle cables?
Set the timing after idle has been adjusted. Oring must be removed for this.
@@HTMR thank you for your reply!
Fixed my bike so happy thanks mate
Okey so i've done what you did in this video (back in september). I setup the squirt just perfect with just a tiny bit of play. Still my bike bogs when i go full throttle on low rpm.
I saw that the idle/pilot jet was slightly damaged tho, On the top were you screw it. It's like a crack.
It is btw a idle/pilot jet 45 (Original). Should i buy a new 45 or should i go higher? The next option that i have from 45 is 48.
Btw it is a KTM 525sx from 2004. So it is the exact same carb.
I have this same carb and I have up graded my 1990 Dr 350 and I want to put this carb on my 350, is there recommended jet size for this conversion?
Awesome video man! I am restoring a 02 DRZ 400e with the slant style FCR. Unfortunately this carb does not provide a screw to adust AP timing. However, there is a U shaped piece of metal that can be bent to adjust the AP lever up and down. I watched the video multiple times and adjusted the pump even more but i cant quite get it perfect. How can this be transferred to the slant carb?
I'm not familiar with that carb, however you have the right idea to bend the tab or modify the cam.
Thanks for the video, helps a lot. I have a Husqvarna SM610 (600cc) and my carb is Keihin FCR MX 41. Do you know if I change the OEM leak jet for the 45 size that you mentioned , it will works for me???
I subbed! Great video, I wish every video was as on point as this one
Carbs are tricky. Thanks for the help.
Hey Matt. How do you reset the tps if you removed it?
This is hands down the best video on getting the accelerator pump tweaked for maximum performance. Getting that “play” - “slop” is the key! And the Oring is a must. I would also recommend the shorter post diaphragm and smaller leak jet. My crf250r acts like it’s fuel injected.
Yes, I always use a 45 leak. Haven't had to tweak the posts as of yet.
The kits are available at CRF Only website along with instructions. I prematurely ruined the original on my Accelerator pump with carb cleaner😏. Found the CRF Only kits to be a good buy. I’ve picked up two over the years.
This video helped me a lot thank you. I have the accelerator pump dialed in; however, I still notice a slight bog here and there when just cracking the throttle... and sometimes a hanging idle. Would you suspect a pilot jet being too lean?
Hanging idle is lean. Adjust the fuel screw. If you get to 3 turns out, increase pilot jet size : th-cam.com/video/kUw41sUQbTY/w-d-xo.html
@@HTMR thanks!!!! I am 3.5 turns out so I’m definitely lean.
Appreciate the info!!!
Mine 150r keeps dying even after this. Should I upgrade my leak jet?
I tried finding a #78 o-ring and for some reason danco uses weird numbers. For those of you looking a #108 o-ring is the number most manufacturers use it's 1/4 i.d. 3/32 cross section 7/16 o.d. do you know if you can use a #202? Which would be 1/4" I.d. 1/8" cross section 1/2" o.d. if it fits it should last longer?
Great video on a much overlooked topic. Thanks, man. Good work!
Thanks!
Awesome! Definitely needed this video! Running into this problem with the yz450f at the moment…
Just did this to my carb on a 06 250x fixed most the bog issue I had once warmed up and ur going u couldn’t tell no more. Plus jd jet kit
Great vid. Having a hard time figuring out a lean condition and decel popping on my crf 450x. Have to turn the fuel screw out more than 2.5 turns to make it run right without popping exaust or glowing header pipe. Pilot jet is a 60, main jet is a 175. Air box has been opened up and has a fmf pipe. Any advice on what to do to tune it so I can run the fuel screw 1.5 to 2 turns out without the exaust decel popping is welcomed.
You need to richen up the pilot jet. However you already are at a 60??? That is pretty big. Check for vacuum leaks and make sure hot start plunger is clean and operational.
sorry for the late post, great video, crf450x ap pump its working ok but squirt duration is too short, i have the o ring mod and the squirt timing is fine. how to improve squirt duration? bike bog on wot and then recover really hard.
Take a look at the rivet length on bottom of diaphragm. If you have a long rivet, you can grind it down to increase duration.
If the accelerator pump isn’t set up right could it cause the bike to hang revs once the throttle is blipped
Would a dirty fmf pipe or clogged pipe have anything to do with spark ?
nice vid, i appreciate.i like it how you keep it simple and load it with info,you know other channels all seem scripted and have same old info repeated and sometimes more about the presenter.could you know a thing or two or anything about stators?especially winding lighting coil on to stock stator of a dirtbike?
There are companies that will add a lighting coil. It really depends on year make model and if there is room for one.
THANK YOU SO FUCKIN MUCH!!!! this is a ****** MASTERPIECE!!!! i tried almost every place on earth to calibrate my accelerator pump but nowhere was this clear as this vid!!! MAD PROPS TO YOU MATE!
Your f***in welcome :)
everytime i squirt gas from that little nozle
a get a very thin streak and doesnt seem powerful, ive chained the leak jet to a #35 and rejetted my main jet and pilot anf still does the same, what could the issue be? i have a bad bog (just like yours before the acc pump adjustment)
The o ring hack did the trick!!! Thanks man!
Can I use 2003 yz450f fcr carburetor rebuild kit for 2003 wr450f fcr carburetor? Is it fit?
Bravo Matt…Another classic!
HUGE THANKS.NOW MY BIKE RUNS AMAZING.👌🙏🙌
Awesome vid! You sure have helped me understand. I seem to be having to much squirt. Was looking at the Boysen Quick Shot 3 accelerator pump cover with adjustable leak valve. Would you recommend? Thanks
First let me ask what year make model?
It's a 2001 wr250f.
@@Doctors101 I would just install a 45 leak and oring. Total cost $10. Also make sure fuel screw and pilot jet are setup and you will have a bike that runs mint and save some money. Usually I install 1 larger size on pilot jet to net me 2.5 out on fuel screw.
Thanks really much for your video!!
I gonna try to make this simple mods in my wr250f and kill the bad effect of the bike die when accelerating fast
Great video.. and i have a question regarding the tps. People say that disconnecting tps will reduce the throttle response and bike bogs but if i disconnect the tps and still setup the AP like you did will the bike still lack throttle response or there will be no any issues whatsoever with tps disconnected and AP working as it should. Please help me out.
Why disconnect the TPS? That is usually to control ignition curves.
MatthewMCRepair thanks for replying. But the thing is i am installing this carb in a bike that has no tps connection provided and it actually have a stock carb which also doesnot have tps. It uses mikuni tm 34 style carburetor so i am upgrading it to a carb with an accelerator pump in it.
@@achupudasaini860 Gotcha.
This trick fixed my issues thank you
I don't have my bike in front of me where I am at the moment. Can this be done with the carb still on the bike?
Yes on most models
Adjustable fuel air mixture screw for an FCR39 on a DRZ400. Is there one that will work in the very small void between the carb and the starter motor. I tried the flexible one but it doesn’t like to turn or adjust under the load of the bend.
Is there a nurled finger adjusted mixture screw?
amzn.to/3mqlabJ
THANK YOU! This is the only vid i can find that explains verry clearly how to adjust the accelerator pump! My bike runs perfect now✊😀.
How do you adjust accelerator pump I am rebuilding carb bike starting without choke
@@amandagregg2195 take the black plastic cover of that is on the right side of the carb. And then just turn the adjuster screw to when there is almost no play in the arm. ( the guy in the vid made it more clear then i can do, sorry😅)
Well I went to adjust this, and I couldn't replicate the play you showed so I got confused. Then I realized that the AP isn't squirting at all... Sweet
So what did you do after that?
@@jarredscott2646 soaked in gas, then soapy water, no luck still. Tried squirting carb cleaner through the passage. In the end what worked was pushing fishing line through the passage and moving the check valve back and forth with cleaner in it
Hey so is this on the outside of the carb? And also when I snap the throttle it will big will the accelerator pump fix it?
There is a "green" acceleration pump spring available, from KTM.
It is from the SXS Parts catalogue.
If I mind correctly, it is a stiffer spring, what enhances the volume of the squirt.
What do you think about it?
I can´t really find any informations about this, or reviews.
Thank you for the good video!
Diaphragm spring or arm spring?
@@HTMR arm spring here is a link with the part number www.braeuer-shop.de/artikel.php?id=21676
Great, exactly what I need for my 09 yz250f. I'll try it tomorrow
Very thorough video man. Thank you. Liked, saved, and subbed.
when we have the problem of the engine speed remaining high even after releasing the accelerator, does it have something to do with the adjustment you made?
Your fuel screw and/or pilot jet is too lean. Watch this: howtomotorcyclerepair.com/how-to-4-stroke-mx-fuel-screw-adjustment-yzf-crf-kxf-rmz-fcr/
I know this is an old video but I have a question, would a progressive throttle cable cam have a negative effect on adjusting the pumper?
No, a throttle cam simply changes the pull rate on cable and how the slide raises.
Awesome, thanks! I have this problem ond will fix it tomorrow!
Very informative, any tips on what would cause a ktm 250 sxf with the fcr carb to be impossible to start after stalling it on the trails? It will hot start no problem if you shut the bike off with the kill switch, but won’t start or kick over after my kid stalls it on a log of root.
Does it improve with using the hot start lever?
MatthewMCRepair no it doesn’t, but I’m wondering if I’m kicking it wrong by twisting the throttle when trying to start it after it’s been stalled and over fueling it. My personal bike is a 300 2 stroke so I’m way more familiar with those style carbs that don’t pump fuel when the throttle is twisted. I am going to install a JD jet kit in the fcr carb and hope it’ll start a little easier.
I did check the valve clearance last night and they’re all within spec around .12mm so that rules out that possible issue
@@MrJasonfromcanada No throttle during starting on 4 stroke. The AP will add fuel making it difficult to start.
Fantastic video. Thank you for taking the time!
Thank you so much this made my day
Hey man, love the videos, you just do an excelente job, I have a little issue with my new FCR33 carb, it idles good and when i accelerate from bottom to top (on neutral) it seems good, but when i go to ride, it stumbles at mid rpms (half throttle), it goes like ta...tatata...tata..tata..., Then I keep accelerating at full throttle and the stumble disappears, and runs ok on top of acceleration. I changed the needles and it keeps stumbling at mid acceleration. It only happens when I go to ride, but not on neutral. Please i'll appreciate your comments.
Same problem if you slowly roll from idle to WOT?
@@HTMR i found that the little squirt is not working properly, it squirts bubles of air and fuel
Good leak jet size for fcr39mx for Drz400?????
Great video. I went to go double check my 05 wr450f’s ac pump only to find out it wasnt even squirting at all. The smaller o-ring under the ac pump cover was totally flattened to the point where the hole was pin sized. Also the brass nozzle it squirts out of was clogged. I un-clogged it all bought an all balls rebuild kit and now it squirts just like this video. Cant wait to try it now and see the throttle response difference. It barely even bogged before also
Thanl you so much for the valuable info you provide us !!!!
Thank you so much for helping with theese carburetors, sub for you!
Thanks for the good explanation about how it all works. And thanks for your videos! You are a good explainer.
Hope it’s ok I ask a question?
I am reasonably new in 4 strokes!
I have followed your advice to set the keihin fcr carburettor on my KTM 250 sxf. When my Fuel mix screw is 3 times out, the engine really goes smooth and throttle responding really quickly. But it is very difficult to start. When the engine is hot, it is impossible even with hot start activated. When I turn the screw a half turn in again, its starting right away even hot. But it doesn't sound that crisp and smooth. Don't you think I'm going to size up my pilot jet? Right now I'm running 175 main and 40 pilot, needle in 5th clip. Only change on the bike is a DOMA exhaust and o-ring mod on accelerator pump.
Thanks in advance
OK, sounds like you need to leave fuel screw at 2.5 out, then richen the acc pump shot. What leak jet do you have now?
MatthewMCRepair
Thanks for your reply.
I will try richen acc pump shot.
The leak jet is #65
@@reneandersen667 Go with a 45 leak
MatthewMCRepair much better now with #45 leak👍🏻👍🏻
@@reneandersen667 Don't loop out LOL.
Well done video. Probably the best one I've seen.
i have a 1999 YZ400f, do i have to remove the carb in order to adjust the AP
Should be able to remove the side cover and adjust.
brilliant video. i have a low to mid range bog the when i blast the throttle it goes away and pulls like a beast any ideas.
So if you stay in the throttle during a bog, the engine will eventually recover? What year make model?
+MatthewMCRepair ktm exc 250f 2011 thanks
I have a small bog issue on a ktm 660 lc4 with the fcr-mx carburator. The bike just bogs down for a very small moment when I give throttle fast. The bike works fine but it is verry anoying. It just feels like it hessitates for a momet at first but it works fine after that. Could it be a worn out accpump membrane? the bike is 11yrs old and has been standing for a while. I really like your videos its good help when trying to learn about carburators!
Is this a new issue or has it always bogged? If 11yrs old and sitting for a while, I'd take it apart and clean it before anything else.
I dont know if it has had this issue before but as I just recently got it I dont know. I will start with a proper clean to se if it helps thank you!
MatthewMCRepair its not really a bog its just a slight hesitation. it makes it dificult to slide around a bend and wheelie the bike. its like a small delay when i open the throttle fast.
Is this s slant because that's what I have does this apply. Sorry for the stupid question
I did that and I'm having the same problem, my back doesn't respond good on low, what can it be? I already clean the jets too 😭😭
mate....cheers for these vids....bloody awesome...keep it up...some of us get all the info needed...even with the lighting or whatever lol
Haha thanks for the compliments! I think the lighting was off only in the intro...but who watches that anyway, right?
excellent video. your a pro man.
Great video !!it was very helpful in my wr450f.. Best regards from Argentina
If I do the I ring mod would I need to rejet to a bigger size?
I’ve been wanting to ask you this for a while: what is your auxiliary fuel pump in order to test the carb on the workbench? Pretty cool
Aux tank - amzn.to/2SDyd7X
is it same carb as STONEDER Keihin PZ30
Mate you should upload more often !!!
Trying! I have a full time job and 4 kids. Need to hire someone...LOL.
Hi mate... will this work on my 2001 yz426? Got really bad bog when throttle is snapped open and bike dies, I'm running standard jets. Cheers 👍🏼
Yes, you have one of these carbs. Not sure what leak jet you though. Might also not have one.