1998 YZ 250, snapping sound from case?

[Master of Faster]

Hey guys, I've got a 98 YZ 250 that I recently have been hearing a snapping sound at idle, its seems to be coming for the transmission but its hard to tell for sure. It onlys happens once the bike warms up and its not consistant at all. Maybe every 10 seconds or so you can hear it snap once or twice. I was just wondering if anyone else has experienced this before or might have an idea of what it is before I tear into it guessing.

Also the bike has a surging idle once it warms up, I bought the bike with low hours on it and it has idled like this ever since I bought it, I've recently rebuilt the topend and it seems to be running great but would like a little smoother idle, any ideas on that would be great as well.

Thanks guys.

 

[freakystyley]

does the tranny noise go away or change if you pull the clutch? with or without throttle? all the nuts and bolts tight on the basket/ starter/ etc. or might be a bad bearning somewhere. idle surge may be air leak or clogged/dirty carb - let us know what you have tried?