What causes this R to idle crazy?

[RUNMYTA]

A buddy of mine just purchased an 86 R and it ran fine at first and now at idle it revs up and down eratic, like it is running out of gas. Anything above idle it runs fine. Plus if we are creeping along at slow speeds it will tend to get hot. Sounds like the pilots is lean. What do you guys think? MIKE

[AtvMxRider]

Check for an airleak.

[XANDADA]

try cleaning the carb out

[cracer250]

I would bet that you have a gasket leaking somewhere. Check you base gasket first. Make sure your cylinder nuts are tight all the way around.

This has happend many times to me. The last time, it started idling way up, then way down. I checked everything over and I ended up losing a cylinder nut and my base gasket was leaking.

This might be where your problem is.

has ur friend rejetted it since he got it? if so something might be off!

[Bean]

maybe the pilot jet came unscrewed, or it is partailly clogged, airleak is another one

[Guy400]

Clean around your base gasket and your carb boots. Start the bike and while it's running crazy spray some carb cleaner around the base gasket and see if your idle changes. If it doesn't, go spray where the reed cage bolts to the cylinder, then the air boot where it connects to the reed cage and keep moving backwards one seam at a time. It's important that you only spray one area at a time to help with the troubleshooting. If you're spraying around the base gasket and the idle smooths out while you're spraying you know it's leaking there. Could also be crank seals going bad or you've got reeds that are going bad and are hanging open a little bit.