My buddy has this 1985 350x atc and we've looked up and down the bike and cant see anyway to tighten the chain. The rear swingarm has no bolts to move it and appears to be a solid pc...please help...thanks!!!

 

Unless you have a custom aftermarket swingarm, the rear bearing carrier that the axle rides in rotates and is eccentric, so that when you turn it, the chain either loosens or tightens. There should be some notches on one end of the carrier that you can put a large allen wrench or screwdriver in to turn the carrier. The stock swingarm uses two allen bolts as pinch bolts to keep the adjustment tight once you are finished.

 

sounds like you might have a 200x, or a 200x swingarm(83-85). look at the swingarm pivot. on those years 200x you adjust the chain at the swingarm pivot.