Hi im new to the group and four wheelers but I have some mechanical ability. I have a 96 sportsman 500 my father in law gave to me that's been sitting for a couple years. Changed oil and spark plug, new gas. He said there was some knocking in it before he put it to rest and I finally got
It running and stayed running but sure enough there was a knocking in it and white smoke coming from the exhaust gasket. Shut it down and now would like advice on where to start. Should add when you rev it up the knocking starts going away but there is still the white smoke

 

You can eliminate the clutches by pulling the drive clutch and see if that's the knock. Worn guide buttons in the drive clutch can sound like a rod knocking if they're worn and the spider hits the clutch towers.I've had plenty come in that sounded like diesels. Another is to check the exhaust cam lobe. Plenty of problems on these over the years on ground down exhaust lobes. White smoke can be coolant from a blown head gasket(you can usually smell a sweet exhaust if it is) or can be oil blow by from the piston rings. Best thing you can do is to get a manual so you're not working blind.https://www.tradebit.com/filedetail....service-manual

 

OK I just ordered a clutch puller today and will be waiting on that and found a manual online. I should also mention when I did the oil change the old oil smelled like gas and was very thin. I don't know if that's related at all to the knocking. If it is not the clutch does it sound like a top end fix ? I could handle that but lower end crankcase stuff I'd be pretty clueless on.

 

Thinned down oil would be carb related in most cases from a worn needle and seat. A good carb kit could fix that,but damage may have been done to the piston and rings also. This is where a leak down test can help also before you got down to tearing a top end down.