i have just bought this py90 frame with a 110cc semi auto engine for the kids its been standing for 2 years i have cleaned carb and drained and put fresh fuel and engine oil it starts but with smoke any answers

ian, August 2010

well these are a 4 stroke engine so it shuldnt smoke so i would say the piston/rings are damaged and it needs a rebore and an oversized piston.the valve stem seals can also cause smoke but only at starting not when it running.the chinese motorcycle industry has alot to learn about quality of materials im afraid the rings may well be made out of chocolate.

adam bike doctor, August 2010