Why is my bike's idle speed hunting and how can I fix it?

[Michael47]

I’ve been trying to get my bike’s idle speed set correctly, but it keeps hunting up and down no matter how many times I adjust the screw. I’m not sure if it’s an air leak somewhere or if the throttle body just needs a proper sync.

[Victoria.M]

I had the same hunt at idle once, and I found a cracked intake boot. Replaced it and the idle settled for a while, though it came back after a few days with a corroded vacuum line I hadn't noticed. It felt like chasing air leaks more than anything.

[Chloe88]

Sounds like a leak or the throttle body not syncing right. I swapped in a new throttle body gasket and dabbed around hoses, which cooled the problem a bit, but it never felt totally reliable. I kept chasing small vacuum leaks that didn’t behave the same way twice.

[Adam.H]

Maybe the real problem isn’t a leak at all but a sensor or ignition issue masking as hunting. I once fixed something minor and it was gone for weeks, then came back because of a loose plug. One question: have you checked the TPS and its voltage stability during idle?

[Steven_R]

I’m not sure we’re chasing the same thing. I tried tweaking the screw a dozen times and then rode for a day with the RPM fluctuating between two points, then it quieted down after a tank of gas. Could be fuel pump variation or something random. Either way I didn’t trust it.