Stihl FS80r trimmer slow to power up.

[Highdesignfool]

This old Pro trimmer is in great condition but at idle when I go full throttle it bogs out.

 

[Highdesignfool]

Any ideas why?

 

[r black]

lean ?.....i have one of these i am also working on at the same time... carb problem i am guessing ....amazon has these .....installed on mine runs like a champ .....yes it a china carburetor ....

 

[GrassGuerilla]

Does it get to full rpm if "feathered" or just bogs out above idle? Either way I'd pull the muff, inspect p&c and make sure the muff is not plugged up with either carbon or even a mud dauber nest. Also check fuel line for cracks etc. Assuming all checks out try fattening up the low side about 1/4 turn.

 

[Highdesignfool]

It won't let me upload the video

 

[Highdesignfool]

I put the video on you tube

 

[Highdesignfool]

With it being a Fs80r and the serial number is 266611323
Can someone tell me the factory carb part number?

 

[r black]

WELCOME

 

[GrassGuerilla]

Did you try backing out the L side?

 

[Highdesignfool]

Did you try backing out the L side?

Yeah. Still does it

 

[1Alpha1]

Have you checked the spark arrestor in the muffler?

I have an FS-250R and it was the 1st thing I removed when it was new.

 

[Highdesignfool]

Have you checked the spark arrestor in the muffler?

I have an FS-250R and it was the 1st thing I removed when it was new.

Yes. That was the first thing to go in mine too.


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[Highdesignfool]

I installed a new Stihl carb today and it runs like brand new. I suspect the diaphragm plates or something else in the old carb were bad. Thanks R black for the part number


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[1Alpha1]

I installed a new Stihl carb today and it runs like brand new. I suspect the diaphragm plates or something else in the old carb were bad. Thanks R black for the part number


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Glad to hear that you got it running properly.

 

[Modern Marvel]

I got a couple FS 80r's ,that was one of the best pro trimmers ever to hit the public market. It saddened me when they stop producing them. but for the ones I've ran and the ones I own as long as maintenance was done on a regular basis like cleaning the carbon out of the exhaust ports and the muffler manifold fuel lines/ filter etc. The carburetor was 99% of any problem that I stumbled upon and I always have ran nothing but ethanol free fuel and synthetic oil of good quality but still problems will arise occasionally as expected from everyday use. Don't get rid of that trimmer because it will eventually be one of those old Timers that will be always talked about.

 

[Highdesignfool]

I got a couple FS 80r's ,that was one of the best pro trimmers ever to hit the public market. It saddened me when they stop producing them. but for the ones I've ran and the ones I own as long as maintenance was done on a regular basis like cleaning the carbon out of the exhaust ports and the muffler manifold fuel lines/ filter etc. The carburetor was 99% of any problem that I stumbled upon and I always have ran nothing but ethanol free fuel and synthetic oil of good quality but still problems will arise occasionally as expected from everyday use. Don't get rid of that trimmer because it will eventually be one of those old Timers that will be always talked about.

I totally agree. They don't make them like this anymore. I inspected the clutch recently and it looks almost new. I've never cleaned carbon out of the exhaust ports or muffler manifold. How do I go about that?

 

[Modern Marvel]

There are a couple of ways to do it. You can get online a tool that is basically just a hardened plastic flat-head screwdriver the idea I guess is to scrape out the carbon with it from the exhaust port and muffler once you have removed the muffler from the engine. I think that the tool was made by Echo so that might be a good place to start a search for it online. It can be done with a metal flat-head but you have to be extremely careful to not score the piston and port. How I do it is simply by removing the cylinder head which gives you access to the inside of the cylinder and piston itself for any carbon built up there and makes it very easy to clean those parts. Use paint good chemical solvent I like to use brake cleaner to loosen the carbon up and then take a non lint rag to polish and clean everything off before reassembling it. The muffler is easy you can use the metal flat head and just scrape out the inlet manifold once you get it apart you can see where the carbon is built up at ( be sure not to damage the exhaust gasket) as well as carbon buildup on the gasket. The other way I have not tried but have seen it, if you have an oxygen and settling tank to run straight oxygen through the motor with carburetor off and the engine will scream real high like being fed with nitrous blows out all the carbon you would want to do this obviously without the muffler on and only for a very short period of time. To me it seems like a very dangerous way to do it but I have seen it done. Also if you have any spark arrestor screen that comes stock from the factory do away with that as soon as possible that will build up carbon faster than any other part. If you're running this machine every day then it becomes necessary to clean the carbon buildup every eight months or so but if you're not using it everyday it's good to just take the muffler off, you can always keep a close eye on it this way.

 

[Highdesignfool]

I'll have to try the scraper method

 

[Modern Marvel]

You may want to have the engine stabilized up at a high bench level with good lighting keep the engine upright to avoid carbon scrapings getting on to the piston. And you shouldn't have any problems with it.

 

[GlynnC]

I use popcicle sticks to scrap the exhaust port. Easy to obtain, and you get to enjoy the yummy to prepare the tool for use!