Need help with idle

N

Nff

Guest
I just got my bike back up after a few years and it runs fine. However when I pull the left lever and stop the bike so it idles, the engine gets incredibly loud and starts vibrating hard. I've adjusted the idle pin thing in the carb in a few positions and it's the same. Any advice for getting my idle smooth?
It's a 2 stroke engine kit on a schwinn bike
 


Tyler6357

Active Member
Joined
Sep 28, 2011
Messages
728
Look for air leaks at the carb/intake connection, also start the engine and see if you can feel any air shooting out from around the head gasket.
 
N

Nff

Guest
Look for air leaks at the carb/intake connection, also start the engine and see if you can feel any air shooting out from around the head gasket.
If theres a leakage would I be feeling air blow on my legs when I ride it? Cause I feel that.
If there is a leakage how would I fix it.
 

Tyler6357

Active Member
Joined
Sep 28, 2011
Messages
728
If you can feel air shooting out from the head against your leg while you are riding then you definitely have an air leak. The engine will run but it will have no power because the compression is leaking out. If the leak is big enough the engine won't even run. I've seen these cheap Chinese steel heads become warped from the heat. If you have a leak you should first make sure that your head nuts are torqued to about 15 foot pounds. Vibrations can loosen them and cause a leak. If the head is actually warped I would recommend getting a high compression head with large cooling fins, they really help your engine run cooler but if you don't have the cash you can replace the stock head for under $10----> https://www.ebay.com/itm/47mm-Cylinder-Head-Gasket-for-80CC-Motorized-Bicycle-Bike-Engine-Parts/162713920844?hash=item25e281654c:g:LDoAAOSw7ylZ5Apl Or you can try to fix it by sanding it flat with sandpaper and piece of glass method if you don't have access to a machine shop, and seeing if you can get it to seal. Other things you can do is try another head gasket, and try it, I guess, but if the head is not flat against the cylinder it won't make a difference.
 
Last edited:

Tyler6357

Active Member
Joined
Sep 28, 2011
Messages
728
You should never have air shooting out from anywhere around the head gasket, that connection has to be sealed for compression.
 

crassius

Well-Known Member
Joined
Jul 23, 2012
Messages
4,575
two kinds of leaks - one is leak at intake where air leaks into motor - other is leak within the motor (head gasket or seals) where air leaks out of motor

in both cases, something is not sealing tight, so never hurts to check all
 
N

Nff

Guest
If you can feel air shooting out from the head against your leg while you are riding then you definitely have an air leak. The engine will run but it will have no power because the compression is leaking out. If the leak is big enough the engine won't even run. I've seen these cheap Chinese steel heads become warped from the heat. If you have a leak you should first make sure that your head nuts are torqued to about 15 foot pounds. Vibrations can loosen them and cause a leak. If the head is actually warped I would recommend getting a high compression head with large cooling fins, they really help your engine run cooler but if you don't have the cash you can replace the stock head for under $10----> https://www.ebay.com/itm/47mm-Cylinder-Head-Gasket-for-80CC-Motorized-Bicycle-Bike-Engine-Parts/162713920844?hash=item25e281654c:g:LDoAAOSw7ylZ5Apl Or you can try to fix it by sanding it flat with sandpaper and piece of glass method if you don't have access to a machine shop, and seeing if you can get it to seal. Other things you can do is try another head gasket, and try it, I guess, but if the head is not flat against the cylinder it won't make a difference.
I know nothing about hardware stuff, sorry you advice doesn't resignate with me. I will try tightening any bolt I see.. the engine runs though it's just the high idle I'm mostly worried about
 
Top