Stihl BG50 timing issue?

[kb05]

I have a Stihl BG50 Blower that wants to rip my arm off every time I try to start it.

I researched what might be wrong and everything pointed to a broken woodruff key causing a timing issue, but this search only found info on other small engines with the same symptoms and not this blower engine specifically.

I have since taken it apart and the key appears to be molded as a part of the flywheel. There was a tiny amount of play in the flywheel before it was tightened down so I replaced it. Same amount of play in the new one before testing it again. I don't know if that is normal.

I can get the blower started but I have to have it on the ground and put my weight on it and kind of work in short pulls otherwise it will pull my arm and jerk off the ground.

Any advice is appreciated. Thanks.

 

[ILENGINE]

If that is one of the items with spark advance built into the module, The module could be faulty and not retarding the spark for starting.

 

[Fish]

Pull the plug, and see if it is wet, or has a lot of carbon. Take out the muffler screen and inspect as well.

Give the air filter a good wash in laundry soap with de-greaser.

Let us know what you see.

 

[kb05]

Thanks for the replies. I found a module cheap on ebay so ordered that just in case nothing else works. Spark plug has some carbon on it but doesn't look terrible, It's not wet at all. I cleaned it up a bit but have a replacement on hand. I washed the air filter and am waiting for it to dry but did also order a new one today. As far as the muffler screen, I can't see any way to take the muffler apart. There are no screws on the muffler at all to take the screen out. I can shine a flashlight in it and it looks pretty black.

Thanks again for the help

 

[Fish]

A buildup of carbon in the combustion chamber is likely your problem.
It looks like the screen just slips in and out and is held in place by the metal tang.
I was just wanting more info, as the problem was likely either a flooding carb, or a buildup of carbon, which could be the fault of a real dirty air filter, which would also clog the screen.

 

[kb05]

Thanks for the tip on the muffler screen. I was able to get it out and burn off the carbon build up. I replaced the spark plug and let some carb cleaner sit on top of the piston to see if that would loosen any of the gunk up but didn't do much. Not really looking forward to taking the entire thing apart to clean it but that is probably where I am headed. I can still get it started but just kind of a headache at this point.

I did notice that the nut holding the blower fan on the opposite side had come loose as I heard a metallic rattling as I was trying to start it again. It would not start at all until I tightened the nut down. Wondering if that nut needs thread lock on it or if I didn't tighten it down enough when I had the entire thing apart weeks ago. I did hit it with the impact and figured that was good but apparently was not.

Thanks again for all the advice.

 

[Fish]

Thread compound wouldn't hurt.
And old redneck trick to break up carbon in the combustion chamber was to dribble a tiny bit of water into the carb while the engine is running, but I don't know if I would try it on a tiny engine like that.
Stihl does have a product that breaks up gunk for their 4 cycle trimmers, so it might work a bit.