That's where I would start.
engine cuts out after top speed run
- Thread starter student👍
- Start date
student👍
Active member
that's not it i checked
student👍
Active member
he was right this is what was happening@Idkw much 👍
Your fix is right here.
Post in thread 'continued affordable mods' https://www.diygokarts.com/community/threads/continued-affordable-mods.47501/post-595112
Why did I say low and high speed jets too lean????
Think about this for a min or 2.
You are already too lean on the high side, your combustion chamber is already over heated at WOT.
Now you let off the go fast pedal, butterfly in carb closes, the piston speed is still high, now its trying to pull fuel thur the low speed jet, which is half the size of the main jet......well its too lean to begin with, so combustion temps go even higher.
Now you hit the go fast pedal again, butterfly in carb opens, pulls fuel from the main jet, which is twice as much as the low speed jet, but still too small to begin with.
That cool fuel/air hitting an already over heated combustion chamber is causing an uncontrollably burn, unsteady pressures, inside the combustion chamber and causing it to spit, sputter, stumble, til the temps come back down and every thing starts working together again.
Then you do it again.
the higher the rpm, the worse this situation gets.
Piston and rings can only take so much temperature from a bad tune, then they won't hold pressure above them anymore. You will have more pressure under the piston, then on top of it.
Gasoline is not just a flammable liquid.......it's also a coolant.
Make sense??????
i mentioned the zip tie before. But you say you need it. So I gave up.
Hope this helps, good luck
but i dont have the drill bit yet so i asked about choking it a bit and if that would work
student👍
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I don't have a credit card
or any money for that matter
or any money for that matter
student👍
Active member
Hi
I apologize for the length but I like to explain things throughly.
This is my new account cuz I forgot my password to the other one and yes, it's been a while.
took me some time to get the drill and in the meantime I've just not gone fast.
I drilled the jet to 1/32 like I was told, everything else was keep the same, and when I fired it up, it was running way too rich, even with the idle afr turned as lean as possible, as soon as the engine warmed up it died. I tried to give it gas so that it would pass form the idle jet to the main jet but it would just sort of gurgle and sputter and couldn't even get me going, not to mention the white smoke out the exhaust, which if I'm not mistaken means rich right?
Funny story, I actually tried to make a supercharger for the go kart in order to make it not-as-rich, but I couldn't find any way to mount it so I gave up.
I went back to using the old jet ( cuz I had two identical ones and I just drilled one of them) and I didn't use it for quite a while after that, but I started using it again and yesterday I decided to take off the exhaust cuz I wanted to see if it made a difference and I also wanted to see if it spit
( I also made the idle mix rich to make it shoot flames) and it actually ran so much better, which makes sense cuz the stock exhaust is very restrictive and not long enough for any scavenging benefits. Anyway, I tried to do a top speed run cuz I was feeling confident about how well it was running compared to before, so I did and 1) it didn't cut out after I let off ( I did it a couple times, and 2) I've never been one to believe that exhaust make a difference in performance but I have to be honest, it was noticeably faster than before, I didn't get past 40ish cuz I don't trust. y flywheel.
BUT, I do have to say It IS still lean on the top end, I haven't checked the spark plug yet but I could feel it from the sound and the fact that there were no flames at top speed, which indicates lean, however it did't cut out and trunks better so removing the exhaust must have made some improvement somehow. Or maybe they r not related and I'm just delusional, are they connected?
I apologize for the length but I like to explain things throughly.
This is my new account cuz I forgot my password to the other one and yes, it's been a while.
took me some time to get the drill and in the meantime I've just not gone fast.
I drilled the jet to 1/32 like I was told, everything else was keep the same, and when I fired it up, it was running way too rich, even with the idle afr turned as lean as possible, as soon as the engine warmed up it died. I tried to give it gas so that it would pass form the idle jet to the main jet but it would just sort of gurgle and sputter and couldn't even get me going, not to mention the white smoke out the exhaust, which if I'm not mistaken means rich right?
Funny story, I actually tried to make a supercharger for the go kart in order to make it not-as-rich, but I couldn't find any way to mount it so I gave up.
I went back to using the old jet ( cuz I had two identical ones and I just drilled one of them) and I didn't use it for quite a while after that, but I started using it again and yesterday I decided to take off the exhaust cuz I wanted to see if it made a difference and I also wanted to see if it spit
( I also made the idle mix rich to make it shoot flames) and it actually ran so much better, which makes sense cuz the stock exhaust is very restrictive and not long enough for any scavenging benefits. Anyway, I tried to do a top speed run cuz I was feeling confident about how well it was running compared to before, so I did and 1) it didn't cut out after I let off ( I did it a couple times, and 2) I've never been one to believe that exhaust make a difference in performance but I have to be honest, it was noticeably faster than before, I didn't get past 40ish cuz I don't trust. y flywheel. BUT, I do have to say It IS still lean on the top end, I haven't checked the spark plug yet but I could feel it from the sound and the fact that there were no flames at top speed, which indicates lean, however it did't cut out and trunks better so removing the exhaust must have made some improvement somehow. Or maybe they r not related and I'm just delusional, are they connected?
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Denny
Canned Monster
You have to have some kind of pipe at least to keep the valves from warping on cooldown.
I
ya I put the exhaust back on cuz it was too loud anyway
.( im dumb)
bob58o
SuckSqueezeBangBlow
Did this get solved? Does it sound like a stuck clutch? Does the clutch not disengage after letting off the accelerator? causing the engine to bog down and cut off?
Hi bob
I did but I didn’t.
I do kw that the fix is a bigger jet, so I jv the solution I just haven’t done it yet.
but I’m posixtive that it’s the afr
bob58o
SuckSqueezeBangBlow
bob58o
SuckSqueezeBangBlow
The way I see this (in my head)…
Driver unit engages and locks up when going fast. Then all of sudden you let off the accelerator. The throttle closes so you are cutting off air and fuel to the engine. The clutch; however, stays locked up. Now you have the same load placed upon the engine (because the clutch has not disengaged), but the engine can’t provide the required power (because it’s not getting air/fuel). The engine dies.
After it dies, try to push it. Does the driver unit try to turn with the wheels?
Imagine yourself cutting a lawn of tall thick grass, then halfway down a pass you close the carb’s throttle plate. The engine can’t make enough power to spin the blade to cut the grass, so it dies.
Driver unit engages and locks up when going fast. Then all of sudden you let off the accelerator. The throttle closes so you are cutting off air and fuel to the engine. The clutch; however, stays locked up. Now you have the same load placed upon the engine (because the clutch has not disengaged), but the engine can’t provide the required power (because it’s not getting air/fuel). The engine dies.
After it dies, try to push it. Does the driver unit try to turn with the wheels?
Imagine yourself cutting a lawn of tall thick grass, then halfway down a pass you close the carb’s throttle plate. The engine can’t make enough power to spin the blade to cut the grass, so it dies.
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