Justyn Markland
ArboristSite Lurker
Hi I have a Fs90 4 mix. I have had this trimmer since 2007, and never had any problems from it. But I would like to know if there are any mods for it. Like porting or muffler mods? Any help would be appreciated.
Is there something that is not as corrosive?
Do i do it with a hot motor? And how long do I leave it?
Old post but may help someone with 4-mix engines
Somewhere on his site I saw Stihl "Ultra" cursed for chainsaw yet praised for 4-mix engines for reasons of carbon buildup and hence valve issues
Not voicing opinions just relaying something I remember reading.
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