I have an 86' quadrunner 230 with shaft drive and electric start. The atv has only 300 miles and is in near showroom condition. I noticed a noise that goes clunk just after I mildly rev it while in neutral. In other word... vroom-clunk vroom- clunk.It sounds like it's coming from the muffler but it's hard to tell. Maybe the engine. Since I just bought this ATV is this something to worry about?

 

Is is really a "clunk" sound, or more like a pop?

P.S. I didn't know a Quadrunner230 had a shaft drive.....mine has a chain anyway.

 

The ones with shaft drive were purely utility and had no rear shocks.I would try adjusting the valves.

 

It's more like a popping sound in the exhaust. I was told by a friend who has much experience that it probably was the valves that needed adjusting.

 

Popping sounds can also mean your quad is running lean(maybe the jets are clogged?)
If the popping sound goes away when the quad is warmed up, then that could probably be the case..