I sincerely appreciate videos like this. When “the 2t king” has trouble tuning a carb it makes us peasants feel better about our struggles. I never have gotten the 21mm carb to run right at WOT and I’m very tempted but too lazy to reinstall the smaller carb.
@@49ccscoot there's just something about a carb, they all seem to have their own personalities. Some seem to be rebellious teens others just listen and work as they should
I love your channel, you do what I could never afford 20 years ago! I'd be interested to see if the Chinese PWK copies work as well as the polini PWK, because they do seem to over charge for them.
I think you might have higher egts because you have better cylinderfilling, therefore I think your problem is more likely to be stinger size or compression then jetting.
I would try to find a way to attach the carburetor more level and check for intake leaks between the engine and carb, sometimes even the tinyest leak causes hanging idle when the slide is closed
Thats absolutley crazy. I drive a 35mm Keihin Airstriker with a 165 Mainjet on a 95cc RT. There has to be something very very wrong with your engine. I drove in the DSSC in Germany for a long time (German Scooter Sprint Community) and never met someone with a 250 mainjet in a 34mm carb.
EXCELLENT VIDEOS VERY SCIENTIFIC TRULY INFORMATIVE IM TRULY LOVING ALL THE INFO KEEP IT COMING IM ABSORBING YOUR LEARNING & INCREDIBLE TESTING ,IM A SCOOTER FREAK TO
I had an Same problem simular to this. For me the problem was That I had to much air compaird to gassoline. Honing to high would foul my sparkplug. I ended upp tweeking with my needle to the leenest poisition and changing the air mixture screw to 0,5 0,7. That fixed the isue for me
Hey Brent, great video again. I was wondering if you already checked bowl level and maybe the float valve diameter? A higer bowl level also gives a richer mixture over the whole spectrum. Keep up the good work 💪
I thought about float height, but it hasn't given me any indication that it's going to run out of fuel. usually if it runs out of fuel, it actually gets worse with increasing jet size because it uses up the fuel more quickly. In this case, I think I could hold it wide open as long as I want when the main jet is removed.
I had a situation where my coolant/ head temp was really hot for a liquid cooled build. Stock form the bore max revs is 13.5k rpms, peak 11.5-12krpms. Plug color was perfect somehow but just running really hot. I later understood that the peak power and max rpm were different and not matched for my roost rs5 13.5-14krpm peak power. Had all the right parts but always ran hot. My bike is gone now but a local experienced builder in my area at the time suggested to port it more.
emulsion tubes. wait until you discover how they really work, and what they actually do... its not what the traditional explanation would have you believing. and from what i know of flat slides, the throat affects the transition. round slide, you have cutaway angle. flatslide? the only option is a different throat size. bigger is NOT better.
I really don't want to see it close to 1400 because this is an actual street scoot and that's well above what has worked for me in the past. I definitely wouldn't have the will to hold it WOT and watch it go too near 1400 for long. Definitely shouldn't be there within an 1/8 mile IMO. Typically it will continue to climb beyond what I see in the 1/8 if I go faster. Never really held this one because it's so hot. I shouldn't need such an abnormally large jet either. Stay tuned and we'll see.
It happened to me, i cant get the right tuning on pwk. I try almost all sizes of jets. So, in the end i changed my carb into mikuni flatslide and it works fine.
I know the smaller PWKs use a power jet for extra fuel at wide open throttle. I looked and couldn't see it on your 34. Id imagine it wouldn't be too difficult to fit a power jet to drop the egt and then you could run a more sensible main jet size. Just a thought but good luck with it
The fuel passages on the import (China?) PWK are too small and won't supply a 150 main jet or larger. You must drill out the passageways or it will starve.
Quick question I have 94cc 2fast on my bugeye cases is ported cylinder is out the box. Currently running a pwk 32mm sunworld. My main is 154 pilot 52. Gonna try a 34mm pwk same needle slide specs an emulsion tube. How much bigger of a mine jet should I go up??
I'm gonna guess 175. Could be way off. That's about the same percentage difference in jet size as the area of a 34 vs 32mm bore and would happen to put you in a range that many use with a 34mm.
@@49ccscoot For a couple of years ago i dynoed a moped with a kehin copy, and it had an emulsiontube, and it stuttered just like yours. When i noticed it had such a tube i mounted a undrilled one and all stutters were gone. Long time ago i read that twostrokes doesn´t use emulsiontubes on mainjet, it is a fourstroke thing.
The dyno plan died when I tried to source a drum cheap. Asked all of my friends to BOLO as well. Nothing. Buying one is way out of my budget. With the way I like to test stuff, it would be great.
EGT can be a trap, too rich causes high readings. I said readings. Stop wasting your time, get a lambda oxygen sensor its $150 for a kit and adding a bung is elementary for a welder.
Just curious... Ever use a wideband day to day? I've never put one on a two-stroke. I know that Koso does, or at least did, sell 2T adapters to keep from fouling the O2. Always wondered if that works or if it's still a tuning only install. Most that I've talked to only use them for tuning and then cap the bung and go back to EGT/CHT for regular use.
@@49ccscoot I have not fouled mine yet and I believe they'll foul quick if your tune is too rich, you can only image what spooge would do. I try to target close to Stoich and when it runs near stoich, a new spark plug comes out clean after a couple hour flight. The O2 will have a layer dry carbon. I do remove the O2 sensor after dialing in the new settings and cap it with a O2 bung plug. I monitor Density Altitude and with that developed a jetting chart (using the O2) for -2000 to +8000 ft density-altitude conditions. DA compensates for temperature, barometer and humidity, creating an apples to apples comparison of tunes regardless of your sea level physical altitude (which is misleading, DA is key here). I've proven the charts effective all last season. I've got several hours on a previously used sensor (I own 3 wideband sensors, I do car tuning). The sensor bung is located in the fat part of the pipe per Slavens advice (from a video). The way I see it with my aviation application, I can turn a 5 hour tuning session into a 5 minute tuning session. Match throttle position at the area of concern with the carburetor circuits, and from there you can make very good conclusions about what to change. Example, you're lean at 22% throttle, the carb progression chart shows the needle is the main component at 22% throttle. Even though adjusting the pilot and main jet will impact fueling at 22% throttle. My method is to 1) set pilot jet, idle and coming off idle, 2) set needle close enough, 3) set WOT main jet, 4) check adjust pilot to perfection, 5) check adjust needle to perfection, 6) check adjust main to perfection, 7) done
@@RwP223 I'm surprised to hear you look for stoich. At least if you mean WOT. I would expect to aim for 12.5:1 or so, figuring probably just a little richer than typical four-strokes... but I guess it works if planes aren't falling out of the sky. I record DA because the dragy provides it on all runs so it's in my spreadsheets. Operating on land in a small radius for tests, a good day and a bad day are only 1000 or maybe 1500ft apart, which I assume is nothing compared to what you'd see tuning aircraft. Thanks.
I feel like your problem is your needle position put it in the middle then start from there pilot 48-52 is good enough and mainjet should be somewhere 120-165 i would start from where u had it but with needle position in middle (center) my problem was engine leak from the exhaust flange and cylinder port
You know what i changed my mind on pwk carbs they are a pain in the ass to tune and it runs hotter than any other carbs i experienced the same things when i ordered a 24pwk for my other bike. What you experienced the same things i experienced... Doesn't matter what mainjet i use, feel so un tuneable...
Your production and testing is second to none. Love this channel
Thank you!
I tend to use 150-180 jets on this kind of carbs, my biggest suggestion would be to start everything over from standard settings…
I sincerely appreciate videos like this. When “the 2t king” has trouble tuning a carb it makes us peasants feel better about our struggles. I never have gotten the 21mm carb to run right at WOT and I’m very tempted but too lazy to reinstall the smaller carb.
The king would be Jan Thiel.
Thank you!
Cant wait for the next episode
Pwk have sometimes problem with fuel flow from the fuel tank.maybe check that
This reminds me of when i did my first carb tuning. I couldn't figure out why nothing worked. Hope you fogire our the issue soon
I've done a lot of carb tuning and somehow they still find ways to make it look like it's my first time. lol
@@49ccscoot there's just something about a carb, they all seem to have their own personalities. Some seem to be rebellious teens others just listen and work as they should
Hey Brent! Have you ever considered to change the EGT sensor to a wideband O2? I think with that, finding the right set would be much easier.
Thought about adding one, but I haven't wanted another big bung in the pipe and more gauges. It may come to that.
I love your channel, you do what I could never afford 20 years ago!
I'd be interested to see if the Chinese PWK copies work as well as the polini PWK, because they do seem to over charge for them.
Love your videos about scooters, cant wait for the final tuning! Greetings from Poland!
I think you might have higher egts because you have better cylinderfilling, therefore I think your problem is more likely to be stinger size or compression then jetting.
I would try to find a way to attach the carburetor more level and check for intake leaks between the engine and carb, sometimes even the tinyest leak causes hanging idle when the slide is closed
I spent two months tuning a pwk for one of mine but it was all worth it once it was dialed in 😂
Thats absolutley crazy. I drive a 35mm Keihin Airstriker with a 165 Mainjet on a 95cc RT. There has to be something very very wrong with your engine. I drove in the DSSC in Germany for a long time (German Scooter Sprint Community) and never met someone with a 250 mainjet in a 34mm carb.
Agreed ❤
EXCELLENT VIDEOS VERY SCIENTIFIC TRULY INFORMATIVE IM TRULY LOVING ALL THE INFO KEEP IT COMING IM ABSORBING YOUR LEARNING & INCREDIBLE TESTING ,IM A SCOOTER FREAK TO
good video, and hope for speedy recover after the wrist surgery!
Thanks. I'm doing well with it.
I had an Same problem simular to this. For me the problem was That I had to much air compaird to gassoline. Honing to high would foul my sparkplug. I ended upp tweeking with my needle to the leenest poisition and changing the air mixture screw to 0,5 0,7. That fixed the isue for me
Hey Brent, great video again. I was wondering if you already checked bowl level and maybe the float valve diameter? A higer bowl level also gives a richer mixture over the whole spectrum. Keep up the good work 💪
I thought about float height, but it hasn't given me any indication that it's going to run out of fuel. usually if it runs out of fuel, it actually gets worse with increasing jet size because it uses up the fuel more quickly. In this case, I think I could hold it wide open as long as I want when the main jet is removed.
Honestly. I haven't had good luck with polini carbs. I'd go a keihin air stryker pwk over a polini any day.
I had a situation where my coolant/ head temp was really hot for a liquid cooled build. Stock form the bore max revs is 13.5k rpms, peak 11.5-12krpms. Plug color was perfect somehow but just running really hot. I later understood that the peak power and max rpm were different and not matched for my roost rs5 13.5-14krpm peak power. Had all the right parts but always ran hot. My bike is gone now but a local experienced builder in my area at the time suggested to port it more.
If only based on coolant temp, I would investigate the entire cooling system first.
emulsion tubes. wait until you discover how they really work, and what they actually do... its not what the traditional explanation would have you believing.
and from what i know of flat slides, the throat affects the transition. round slide, you have cutaway angle. flatslide? the only option is a different throat size.
bigger is NOT better.
Anything below 1400 and above 1200 are acceptable EGTs in dirt bikes with aluminum bores kinda the standard, you were pretty close with this already.
I really don't want to see it close to 1400 because this is an actual street scoot and that's well above what has worked for me in the past. I definitely wouldn't have the will to hold it WOT and watch it go too near 1400 for long. Definitely shouldn't be there within an 1/8 mile IMO. Typically it will continue to climb beyond what I see in the 1/8 if I go faster. Never really held this one because it's so hot. I shouldn't need such an abnormally large jet either. Stay tuned and we'll see.
Thats a huge carb on that small displacement,just change to bigger jettings.
It happened to me, i cant get the right tuning on pwk. I try almost all sizes of jets. So, in the end i changed my carb into mikuni flatslide and it works fine.
Drill the fuel passages so it passes 8 oz per min with the float removed. Otherwise it will starve.
I went to parts for scooters they have odd ball jet sizes for the pwk
the bigger the carb the harder to tune :)
I know the smaller PWKs use a power jet for extra fuel at wide open throttle. I looked and couldn't see it on your 34. Id imagine it wouldn't be too difficult to fit a power jet to drop the egt and then you could run a more sensible main jet size.
Just a thought but good luck with it
No power jet on this. My issue is that I know the carb can work well with a more standard sized jet on the same engine setup.
@@labrikorn_3299 Different ignition. Same exhaust at one point.
The fuel passages on the import (China?) PWK are too small and won't supply a 150 main jet or larger. You must drill out the passageways or it will starve.
Quick question I have 94cc 2fast on my bugeye cases is ported cylinder is out the box. Currently running a pwk 32mm sunworld. My main is 154 pilot 52. Gonna try a 34mm pwk same needle slide specs an emulsion tube. How much bigger of a mine jet should I go up??
I'm gonna guess 175. Could be way off. That's about the same percentage difference in jet size as the area of a 34 vs 32mm bore and would happen to put you in a range that many use with a 34mm.
Most likely an air leak from the oil rings at the crankshaft
It passed leak tests.
Try swapping the needle jet atomizer that has lesser holes or smaller ones.. that would rich up the mixture
keihin pwk has i think 8 and 10 hole needle jet atomizer... But idont know if your carb has the option...
@@ninocabugaoii399 There are a few atomizers for it.
@@49ccscoot yeah. Less holes should help richen it up.. might help.
If having an emulsiontube at the main jet, plug the small holes.
Making it a non emulsiontube.
This comes with a 30 hole. IIRC there are 20 and 40 available for this. If it comes to that, I'd probably start with a 20 and see what happens.
@@49ccscoot For a couple of years ago i dynoed a moped with a kehin copy, and it had an emulsiontube, and it stuttered just like yours.
When i noticed it had such a tube i mounted a undrilled one and all stutters were gone.
Long time ago i read that twostrokes doesn´t use emulsiontubes on mainjet, it is a fourstroke thing.
Make a dyno, or save for one. At the very least get Endmod2T. Both will show that you're wasting your time on oversize carbs.
The dyno plan died when I tried to source a drum cheap. Asked all of my friends to BOLO as well. Nothing. Buying one is way out of my budget. With the way I like to test stuff, it would be great.
Does ryan do the porting on his rc1?
He port matched the cases. I think that's about it.
Does that PWK have a powerjet? If so, what size?
It's a non power jet version.
@@49ccscoot May I ask what your 2T oil ratio is?
@@pirrracy 4oz per gallon (32:1) with AMSOil Dominator.
Try to utilize the lectron again?
Might as well with the way this is going.
Cant be any worse
Oh gosh no
So much for an easy swap.
:3
👍👍👍🔥🔥🔥🤝🤝🤝
EGT can be a trap, too rich causes high readings. I said readings. Stop wasting your time, get a lambda oxygen sensor its $150 for a kit and adding a bung is elementary for a welder.
Just curious... Ever use a wideband day to day? I've never put one on a two-stroke. I know that Koso does, or at least did, sell 2T adapters to keep from fouling the O2. Always wondered if that works or if it's still a tuning only install. Most that I've talked to only use them for tuning and then cap the bung and go back to EGT/CHT for regular use.
@@49ccscoot I have not fouled mine yet and I believe they'll foul quick if your tune is too rich, you can only image what spooge would do. I try to target close to Stoich and when it runs near stoich, a new spark plug comes out clean after a couple hour flight. The O2 will have a layer dry carbon. I do remove the O2 sensor after dialing in the new settings and cap it with a O2 bung plug.
I monitor Density Altitude and with that developed a jetting chart (using the O2) for -2000 to +8000 ft density-altitude conditions. DA compensates for temperature, barometer and humidity, creating an apples to apples comparison of tunes regardless of your sea level physical altitude (which is misleading, DA is key here). I've proven the charts effective all last season.
I've got several hours on a previously used sensor (I own 3 wideband sensors, I do car tuning). The sensor bung is located in the fat part of the pipe per Slavens advice (from a video). The way I see it with my aviation application, I can turn a 5 hour tuning session into a 5 minute tuning session. Match throttle position at the area of concern with the carburetor circuits, and from there you can make very good conclusions about what to change. Example, you're lean at 22% throttle, the carb progression chart shows the needle is the main component at 22% throttle. Even though adjusting the pilot and main jet will impact fueling at 22% throttle.
My method is to 1) set pilot jet, idle and coming off idle, 2) set needle close enough, 3) set WOT main jet, 4) check adjust pilot to perfection, 5) check adjust needle to perfection, 6) check adjust main to perfection, 7) done
@@RwP223 I'm surprised to hear you look for stoich. At least if you mean WOT. I would expect to aim for 12.5:1 or so, figuring probably just a little richer than typical four-strokes... but I guess it works if planes aren't falling out of the sky.
I record DA because the dragy provides it on all runs so it's in my spreadsheets. Operating on land in a small radius for tests, a good day and a bad day are only 1000 or maybe 1500ft apart, which I assume is nothing compared to what you'd see tuning aircraft.
Thanks.
I feel like your problem is your needle position put it in the middle then start from there pilot 48-52 is good enough and mainjet should be somewhere 120-165 i would start from where u had it but with needle position in middle (center) my problem was engine leak from the exhaust flange and cylinder port
Stay tuned. I'll try out some needles, center position, next time.
You know what i changed my mind on pwk carbs they are a pain in the ass to tune and it runs hotter than any other carbs i experienced the same things when i ordered a 24pwk for my other bike. What you experienced the same things i experienced... Doesn't matter what mainjet i use, feel so un tuneable...