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Muffler loading up

Jerrys Lawn Service

LawnSite Member
I've been having some trouble with my Stihl FS 80 trimmer
the muffler keeps clogging up with oil residue I am using
the correct mix 50-1, but it still is bogging down and whats
even more crazy is the hotter the temp is outside the worse
it becomes! I've taken it to my local dealer and was told
that I wasn't running it hard enough, he said wide open all
the time, I told him that this wasn't possible all the time
because of people, cars, houses, WINDOWS! What do you guys think? I talked to another landscaper and he said he's
having the same problem.

Good Luck to all


LawnSite Platinum Member
Did you take the spark arrester screen off?


LawnSite Senior Member
Columbus Ga
Question are you using the spark arsetor?if so get rid of it unless are are in a fire hazard area.if not i probally would look at the carb that were the mix enters the engine,
it may be nasty inside allowing more fuel the need or adjusted for,if thats it just clean it and rebuld it.This would probally explain the lack of rpms these are my thoughts anyway.

Eric ELM

Husband, Father, Friend, Angel
Chicago, IL USA
If it's not the spark arrester, it's carbon build up on the exhaust port. Take the muffler off and see if carbon has built up around the exhaust port, if so, clean it out and it will run full RPM's again, like when new. I clean the exhaust port opening each year on the string trimmers. You won't believe the difference. The Back Pack Blowers normally don't have this problem, since they are usually running wide open most of the time.


LawnSite Member
I just bought the fs 80 last week and no promblems eith it yet.

Hey eric thanks for the info. i had never done that to my echo's.



LawnSite Fanatic
N.E. Wisconsin
Follow Stones advice as well as take the screen out. That heave petroleum based 2-cycle gums everything up and smells bad. You will soon change all of your 2 cycle to synthetic.
I did years ago and havent had a problem.
I even use it in the Lawnboy. The only problem is that now I get bit by mosquitos because I am not mowing in the blue cloud.