my ATV doesnt like to idle, and smokes! what is it?

Question

i have a 1994 Polaris Sportsman 4x4 400cc 2 stroke. having raced motocross, i understand that 2 strokes smoke anyway. this is a lot of smoke!

it is white smoke, and i am pre-mixing the gas with oil (36-1). when i bought the ATV, the oil pump was shot, and it wasnt worth the 420 dollars plus tearing down to frame. the oil pump was stuck in the full-open position, so it fouled plugs about once an hour (better than the alternative i guess) the pump is disconnected.

now it still fouls plugs, but more like once every 4th trip. runs great at throttle, but once back to idle, lasts about 4 seconds and dies. starts back up fine. idle screw is pretty high, and responsive. what is going on?

the oil pump was for pre mixing oil. there is a seperate tank for the oil, and the pump changes speed with the throttle, making the mix richer /leaner depending on throttle position. it was a cool feature.

Answer 1

Well first, what raises a eyebrow with me is that you say that your 2 stroke has a oil pump. I have never known a 2 stroke engine to have a oil pump, why is one needed when you are already mixing the oil with gas. Second, I would look at the oil /gas ratio that you are mixing to see if it is correct. 36:1 is a little bit on the sticky side. Contact your Polaris dealer to be sure if you are using the correct mixture. Im not saying that you aren't using the correct mixture, im saying just check with a Polaris dealer to be sure. Third, a 2 stroke engine is not made to just putt putt around on, you did say that you have raced motocross, so I hope you are keeping that engine blown out. A 2 stroke is made to run and be run wide open.

Answer 2

If it is water cooled you could have a oil seal out , head gasket leak,Broken ring(s),crank seal out on clutch side.