Stihl BG 85 Issue

[vsiddhartha]

Hi all! I picked up a non-running Stihl BG 85 blower from my father in law. I replaced and gapped the spark plug, replaced the air and fuel filters, cleaned the fuel tank, put in fresh fuel, and adjusted the carburetor. It starts easily now and idles smoothly, but won't reach full power. The throttle responds quickly, it seems like it reaches full power for a second, then it bogs down to low power. Adjusting the high speed screw as far out as the stop will let me (3/4 turn) gets it to run at higher power, but it spews blue smoke and runs really hot.

Any ideas on what the issue is or how to fix it? Thanks!

 

[mechanic mark]

https://m.stihlusa.com/WebContent/CMSFileLibrary/instructionmanuals/STIHL-BG-55-65-85-SH-55-85-Owners-Instruction-Manual.pdf

See pages 17-21.

 

[dcgrazier]

Check the spark arrester. It is on the exhaust port of the engine. Make sure it is clean. A clogged screen can cause the problem you are experiencing. I had the same problem with my Stihl line trimmer.

 

[vsiddhartha]

Check the spark arrester. It is on the exhaust port of the engine. Make sure it is clean. A clogged screen can cause the problem you are experiencing. I had the same problem with my Stihl line trimmer.

Thanks! I did check the screen. I don't have the one that screws in, the one I have slides in and out. But the screen was clean. I've already followed all the procedures referenced in pages 17-21 of the manual. I think there may be some other issue with the carb or muffler.

 

[bertsmobile1]

Pull the muffler right off and check he exhaust port.
People like to run too much oil in the mix and this builds up carbon on the exhaust port strangeling the engine .

 

[vsiddhartha]

Pull the muffler right off and check he exhaust port.
People like to run too much oil in the mix and this builds up carbon on the exhaust port strangeling the engine .

I pulled off the muffler, and the exhaust port is clean. The bottom of the muffler was really wet though, there is apparently a lot of fuel blowing through... Any other ideas, or do I need to replace the carb?

 

[Fish]

Take the carb off and the cover with the 4 screws, you may just have a loose welch plug.

 

[Fish]

Here is the price of a new one from last year's Stihl price list:

4229 120 0606 CARBURETOR (BG/SH 55/85) $44.32