# FS80 trimmer - acting like it is hitting a rev limiter



## 302w (Jun 9, 2022)

I have a new-to-me FS80. Starts well/runs well now that I put a new coil on it. 

Under full throttle, the trimmer acts like it is hitting an electronic rev limiter like a car and shakes violently when doing so. 

Can anyone tell me what is happening when this is occurring? Is the trimmer indeed hitting a rev limit of sorts and I need to turn the H screw in to stop it?


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## DND 9000 (Jun 9, 2022)

It can be the electronic rev limiter. If this is the case your trimmer is tuned to lean and you have to richen the mixture to stop it.

The trimmer can also 4 cycle hard if it is tuned to rich. But for a real noticeable shaking it would have to be much to rich. I think the first point is the reason for your problem.


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## ironman_gq (Jun 30, 2022)

My FS131 was so lean that it would stall at WOT, richened it up till I found the rev limiter and went a little bit richer. Just enough to drop the RPM's down under the limiter. Granted mine is a 4-mix motor but the tuning process on a limited coil is the same. It could also be that the trimmer shaft and gearbox need some grease, a dry shaft can cause a nasty vibration.


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