Stihl BG55 just quit running

da324

Forum Newbie
Joined
Feb 26, 2023
Threads
1
Messages
4
Hi,
My Stihl BG55 stopped running yesterday. It was making a bit of noise, kind of like a small rattle that wasn't normal, and was periodically losing power before it abruptly stopped. Initially, the flywheel wouldn't move when it shut off, so I took the cover off, removed the spark plug, and freed the flywheel up. I started it back up twice and it ran for about a minute and it started to lose power before it stalled. Those two times it wasn't an abrupt shut off like it did initially, more of a slow stall. It didn't lock up the flywheel again, but after two tries it will not start. I checked the spark arrestor and it was clean. I checked the air filter and it was clean. The spark plug looked great. I've had this unit about 5-7 yrs and never had an issue until yesterday. Any ideas would be appreciated.
 

bertsmobile1

Lawn Royalty
Joined
Nov 29, 2014
Threads
64
Messages
24,647
Take the muffler off and have a peek at the piston & cylinder walls
ME thinks it will not be a pretty sight
 

StarTech

Lawn Royalty
Top Poster Of Month
Joined
Feb 19, 2020
Threads
75
Messages
10,109
Okay first when you remove the spark plug is it coated with grey looking stuff? If so you might have ran it too lean which cause PNC damage. Also you can pull the muffler and look at piston for damage from overheating.

Most PNC is from straight gassing but running too lean on oil or fuel mixture can also cause the same damage.
 

mmoffitt

Well-Known Member
Joined
Aug 21, 2018
Threads
1
Messages
115
Time to look for a new one! good luck and be well...also winter is far from over ..at least here!
 

da324

Forum Newbie
Joined
Feb 26, 2023
Threads
1
Messages
4
Okay first when you remove the spark plug is it coated with grey looking stuff? If so you might have ran it too lean which cause PNC damage. Also you can pull the muffler and look at piston for damage from overheating.

Most PNC is from straight gassing but running too lean on oil or fuel mixture can also cause the same damage.
The spark plug looked perfect, I'll pull it again and have another look. What is PNC? I've always used the manufacturers specs for fuel and oil mixture. Thanks!
 

da324

Forum Newbie
Joined
Feb 26, 2023
Threads
1
Messages
4
The spark plug looked perfect, I'll pull it again and have another look. What is PNC? I've always used the manufacturers specs for fuel and oil mixture. Thanks!
The spark plug looked perfect, I'll pull it again and have another look. What is PNC? I've always used the manufacturers specs for fuel and oil mixture. Thanks!
I've attached a few pictures. The piston has some slight scoring at the top, but none on the bottom. Is it possible I sheared a flywheel key? I'm curious because there was a small rattling sound before it stopped running.
 
Top