Stihl FS90r trimmer, sluggish throttle, "heavy" top end.

[Joseph Acquisto]

FS90r has very sluggish throttle response. Some times feels like none, then it "catches up". Top end seems "heavy", that is does not seem to reach high enough RPM and seems down on power even then.

Recent new plug, due to hard start, and ran fine. Adjusted valves a while before that. Spark arrest screen is clean. Fuel has been sitting for a month or so. The air filter looks terrible and I have some on order.

By terrible, I mean dirty and oily. The entire carb area is quite dirty and oily looking in fact. I suppose I should clean that off with some carb cleaner.

Any ideas, beyond change filter and try again?

 

[jeffpack1957]

You can get a brand new carb for like 12$. My fs90 was acting up, and rather than mess with it, a new carb fixed it all up.