Variable RPM

[Michael H]

I have a 2008, AR210 and one of the engines has periodic pulsing/changing rpm. It will run at 6500 an then suddenly jump to 7000 or 7500. The other one remains stable the entire time. Does anyone have an idea why or what would cause the RPM to jump like that. It seems if I move the throttle around, sometimes I can get it to stabilize. Is this likely to be the throttle cable or something in the carburator or elsewhere?

 

[buckbuck]

Welcome @Michael H
It is very likely the spark plugs need to be changed. Yamahas seem to be fussy about wanting fresh plugs. It is easy to do. Many of us just replace them every year even if they are not showing performance issues.