A sport 400 was given to me with the chain broken, tranny case busted, and with the engine blowing white smoke out of the exhaust. Got the new chain and new tranny, but now I have the engine to deal with. I never dealt with a bad engine as my other toy was bought brand new. I started the engine and it sounds like there is excessive popping noise coming from the engine and white smoke coming out of the exhaust. Any ideas? I don't know what happened to the quad before all the destruction began but I just want to fix it and ride since it was free. thanks for the input

and yes I am a rookie to this board.

 

white smoke that smells sweet is indication of antifreeze burning in the motor. first possibilitie is the head gasket. the second very ugly possibility is there is a hole in the case between the crank case and the counterbalance. in combination with a very bad water pump seal

 

no sweet smell...more like burning. are 2 cycles typically supposed to smoke? could it be that the gas in there was not properly mixed? like i said before this is how i got it

 

well two strokes do smoke, whose when cold. If it will run. keeping an eye on the coolant level for a short ride if it is ok.
go for a long ride. top up the oil tank before you go and see how much it uses in one tank. the oil pump cable could be old of adjustment causing to much oil at an idle.

 

Well.. smoke=burning too much oil.
"popping"=piston bearings going, or rings are bad.

just my guess