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View Full Version : Stihl FS 80R bogging at WOT


jtkplc
03-17-2007, 11:48 PM
At the end of last season I was having problems with my Stihl FS 80R bogging down on and off when I would run it wide open. It wouldn't do it all the time, it seemed to come and go. Sometimes when it would bog down, if I brought it back to idle and then reved it up again it would come out of it for a little while. I don't know what else to check. My dad is a mechanic, but not for small engines. We've checked everything he knows about including the fuel/air mix ratios, I put a new spark plug in, and checked fuel lines. Does anyone know what else to check or what could be wrong? I want to try to fix it myself if I can to save the money from taking it in to my dealer. Thanks, jtkplc.

RLW
03-18-2007, 02:21 PM
Did you pull out the spark arrestor from the muffler ? They come out like a spark plug. Thing will gum up from 2- stroke oil & choke out the engine with back pressure. If you can't see through the mesh, burn it off with a torch & hit it with a wire brush.

DandG
03-18-2007, 03:08 PM
yea i second his opinion about the spark arrestor i have fixed many a stihl trimmer that way

Tadams
03-18-2007, 10:39 PM
Clean the spark arrestor and if that doesn't fix it you will have to rebuild the carb. I just got finished with mine. It is not very hard to do- you can get a rebuild kit at your dealer or through one of the online suppliers. You will have to take the carb off and get the numbers off of it to get the right kit. If you decide to do this yourself- send me a pm and I can walk you through it.

TurfConcepts,Inc
03-18-2007, 11:23 PM
My old FS80 does the same thing. I pulled the arrestor and changed the spark plug and it ran fine for a day. Now it is back to it's old ways. Tadams, can you post the step by step for the carb rebuild?

jtkplc
03-21-2007, 11:49 PM
I will have to double check, but I'm pretty sure I checked the arrestor and it wasn't even there. I think it must have fallen out somehow because there was no screen where there should be. I guess a rebuild is in my future. How much do they cost? Thanks for your help.

Budget
03-22-2007, 09:04 AM
At wot sounds like its a lean bog, make sure carb is adjusted right.

jtkplc
03-22-2007, 09:44 AM
At wot sounds like its a lean bog, make sure carb is adjusted right.

What exactly does that require doing?

khouse
03-22-2007, 10:00 AM
Make sure the fuel tank is venting. When it acts up loosen the fuel cap and see if this takes care of the issue? Just another thing to check....

EMTDUCK1984
03-22-2007, 10:38 AM
Sounds Like You Have Some Water Or Trash In The Carb When You Accelerate It Causes The Trash To Get Over Near The Needle And Closes The Needle Off Slightly So It Acts Like It Boggs Down

jtkplc
03-22-2007, 12:08 PM
Sounds Like You Have Some Water Or Trash In The Carb When You Accelerate It Causes The Trash To Get Over Near The Needle And Closes The Needle Off Slightly So It Acts Like It Boggs Down

What do I do to check that and get the trash or water out?

jtkplc
03-22-2007, 12:10 PM
Make sure the fuel tank is venting. When it acts up loosen the fuel cap and see if this takes care of the issue? Just another thing to check....

I'll have to check that. I know you check the simple things first when it comes to mechanic stuff.

no body does it better
03-22-2007, 10:48 PM
also check compression to much leakage by rings will give same prob