Only runs while i pedal

[Tucson_Toast]

I have an 80cc grubee that i just replaced the piston on and it will not stay running under its own power. If i pedal it for a while it turns over, even gets up to running temperature but will die as soon as i stop pedalilng. Stuck.

 

[crassius]

I'd take out plug and see if it turns easily - sometimes thing drag if something is mismatched when replaced.

if OK, then I'd check compression and gaskets and seals, then a way too lean fuel flow

 

[Kioshk]

New rings as well? I had a similar problem a while back. Turned out the rings were defective: they had a slight inward bevel that allowed expanding gas to pass over them. A used pair I had laying around completely resolved that heartache.

 

[Tucson_Toast]

Pulled the exhaust off and it came right to life. Wayy too rich air:fuel ratio