87 KDX200 idle surges.

[ChrisCoyle]

I have a 87 KDX200. After the bike warms up the idle will begin to surge without touching the throttle. Any ideas guys?

 

[bajus22]

Check for leaks or cracks on the cylinder intake boot, right after the carb.

 

[ChrisCoyle]

Thanks for replying. I actually replaced the intake boot which was deteriorating with one I obtained from a salvage motor but I can examine it more closely. Any possibility it could be main bearing seals?

 

[bajus22]

It could be. But I like to check the simple fixes first. Is the carb clean?

 

[Dirtdame]

Or go up one size on your pilot jet. I'm running a 30 in both my 86 KDXs, but I could probably get them to idle more evenly if I put in a 35. Unfortunately there isn't any air screw on those carburetors, so changing the pilot is the only way to fix that problem. And if your bike was running fine a while back with the same pilot jet, then the pilot jet is probably starting to get dirty.