new build runs kind of rough

GoldenMotor.com
sneekypete

sneekypete

New Member
Oct 22, 2015
16
0
0
Lawrence KS
Just put together an 80cc kit and the motor won't run on idle and it runs kind if rough.. Once it gets going it smooths out, but if I slow down or com to a stop the motor starts running rough-- if I stop completely the motor idles for a couple seconds and dies.. I have not adjusted the carb in any way, and the kit's instructions didn't have any info on adjusting the carb.. Also, there is a bit of oil leaking out between the muffler and the block-- I tightened it down but I'm afraid to tighten it any more because I don't want to strip out the threads in the aluminum block... Any help would be greatly appreciated!!!
 
2door

2door

Moderator
Staff member
Sep 15, 2008
16,302
175
63
Littleton, Colorado
New engines don't always run smooth. Give it a little time and a few miles.
We don't know what carburetor you have but most will have an idle speed screw. It isn't a needle valve but a mechanical stop that determines how far closed the throttle will go. Screw it in to increase idle speed, out to decrease.

Running rough at slow speed might be normal if you're trying to go too slow with the clutch engaged. Anything below about 10 mph and you should disengage the clutch and pedal the bike.

The kit gaskets are not the best quality. You'll be better off to replace them with good quality gasket material. The exhaust manifold flange is also probably warped from the welding process. It needs to be ground or sanded flat for a good gasket seal.

A reliable torque wrench is a good investment. Those 6mm studs should not be tightened more than about 60 inch pounds or you run the risk if thread damage.

Good luck.

Tom
 
sneekypete

sneekypete

New Member
Oct 22, 2015
16
0
0
Lawrence KS
Thanks for the info Tom, I think I might have to tear the engine down and see what's going on inside... I'm dealing with the compression issue now
 
Chaz

Chaz

Well-Known Member
Jun 3, 2012
1,004
72
48
Vancouver, British Columbia
Pete, are you using the stock acorn head nuts? If so that might be part of your compression issue. You can replace them with regular nuts or snip the crowns off the stock ones with side cutters or just crush them with regular pliers and fatigue them off. The stock acorns are often not deep enough and the bolt will "top out" and give a false reading on a torque wrench.
 
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