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A still Stihl...

clayman51's Avatar

Join Date: Jan 2010
Posts: 2

01-19-10, 05:02 PM   #1  
A still Stihl...

I've got a very old Stihl FS80 brushcutter that had been running well up until last week when the muffler fell off. the vibrations also loosened the carby...so I tapped the stripped threads and refitted the muffler ... cleaned and installed a carby kit and didn't take careful note of the carby settings... gee, how hard can it be? VERY ! [stupid + hurry = worry] frustration is building as I can get it to fire and even run, but any throttle and it dies. What settings should I have to start with and any suggestions for the fine tuning would be Greatly appreciated.

a carby diagram would be great to double check all gaskets and diaphram positiongs. thanks

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cheese's Avatar
Forum Topic Moderator

Join Date: Jul 2001
Posts: 16,564

01-19-10, 05:45 PM   #2  
Start with both high and low screws 1 1/2 turns out from lightly seated. Crank it up and hold it at full throttle and turn the h screw in until the engine races like a wild banshee, then back it out until the engine develops a little flutter. Then let it idle and adjust the L screw in until the rpm picks up and the engine begins to hum super smooth, then back it out a bit until the engine lopes or flutters a bit, then set the idle stop screw for desired idle rpm. You may have to go through the procedure a second time to fine tune it even more.

On the fuel pump side, the diaphragm should go next to the carb, then the gasket, then the cover. On the metering valve side, the gasket goes on first, then the diaphragm with the metal disk facing the carb, then the cover.

"Who is John Galt?" - Ayn Rand (Atlas Shrugged)

God bless!

clayman51's Avatar

Join Date: Jan 2010
Posts: 2

01-19-10, 06:23 PM   #3  
Thanks Mr Cheese,

I'll give it another go... Yesterday I was nearly to the point of heaving it into the ocean if I was a bit closer! ...Wayne

geogrubb's Avatar

Join Date: Jun 2006
Posts: 2,333

01-19-10, 07:17 PM   #4  
If you installed the new metering arm with the kit, I would suggest using the old one unless it was very worn, as it has the proper height setting and will save a lot of headaches. Have a good one. Geo

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