Husky 345 has spark and fuel but won't pop

[Overlooker]

I recently acquired a husky 345 that's 15 to 20 years old. It has a brand new spark plug with good spark, and fresh fuel. I can't get it to pop even once. What am I forgetting?

 

[Bob Hedgecutter]

Compression and or timing?

Are you relying on the saw pulling its own fuel into the combustion chamber to make it "pop", or have you tried dribble of fuel directly into the carb throat with the choke open and air filter removed?

 

[Overlooker]

I tried what you have suggested there, and I also tried pouring a tiny bit of fuel into the cylinder and replacing the spark plug. Neither one caused it to pop even once.

 

[HarleyT]

Could be flooded, or a sheared flywheel key.

 

[Overlooker]

Could be flooded, or a sheared flywheel key.

I have removed the spark plug several times to find that it was wet. Using compressed air I blew out the cylinder and dried off the spark plug and tried over. It certainly has been flooded, but that doesn't explain all my problems. A sheared flywheel key certainly might. I'll have to check that out. Thanks!

 

[Bob Hedgecutter]

A lot can happen in 20 years- have you pulled the muffler and glanced a look at the piston through the exhaust port yet?

 

[Overlooker]

No, I haven't. But what could be going on there that would prevent any prevent any combustion at all?

 

[Overlooker]

The saw has a decompression valve. If I pull the pull cord with the decompression valve pushed in versus not pushed in, there is a significant difference. I know there's at least some reasonable amount of compression.

 

[Overlooker]

I would like to check the flywheel key. I pulled the nut, but I can't see where to grab the fly wheel with a puller to pull the flywheel. And any suggestions?

 

[canadian175]

Check and see if coil hacs correct clearance with flywheel. If coil is moved away from flywheel u could haul all day. Also haul muffler of and check piston see if its scuffed up and groves going up it you have problems rings stuck .piston and cylindar shot.i hope the best friend.

 

[Bob Hedgecutter]

No, I haven't. But what could be going on there that would prevent any prevent any combustion at all?

Well you see, you have established there is spark, you have established there is fuel arriving in the combustion chamber- the next likely suspect is lack of compression- pulling the muffler and looking at the piston for the entirety of the stroke can give you visual indication of if and why compression may not be sufficient for combustion to occur.
Very simple check to perform and easier than pulling the flywheel if you do not have the correct tooling or know the tricks to get it off the crank.
Check the piston through the exhaust port- supply photos even- then I am sure HarleyT will be back with a simple method of flywheel removal to check the key is still valid.

 

[Woodslasher]

Well you see, you have established there is spark, you have established there is fuel arriving in the combustion chamber- the next likely suspect is lack of compression- pulling the muffler and looking at the piston for the entirety of the stroke can give you visual indication of if and why compression may not be sufficient for combustion to occur.
Very simple check to perform and easier than pulling the flywheel if you do not have the correct tooling or know the tricks to get it off the crank.
Check the piston through the exhaust port- supply photos even- then I am sure HarleyT will be back with a simple method of flywheel removal to check the key is still valid.

I take a brass hammer and give the crank a few whacks on the clutch side, usually after a few good raps the flywheel will fall off.

 

[Overlooker]

the next likely suspect is lack of compression

95 psi is the best I could get with my Guage. Certainly that's too low for a saw to run well, but would that stop it from firing at all?
I managed to get the flywheel off with a center punch and hammer directed at the end of the crankshaft (thanks to some YouTube videos I watched). Key was okay.
The rest of the news isn't so good. Piston is scored:

I guess I've got a parts saw because I doubt it's worth rebuilding. Besides, I don't really need another 45cc saw.
Thanks to all for the advice. Next time I'll check compression and examine the piston first! O

 

[Bob Hedgecutter]

95 psi is the best I could get with my Guage. Certainly that's too low for a saw to run well, but would that stop it from firing at all?
I managed to get the flywheel off with a center punch and hammer directed at the end of the crankshaft (thanks to some YouTube videos I watched). Key was okay.
The rest of the news isn't so good. Piston is scored:
View attachment 998598
I guess I've got a parts saw because I doubt it's worth rebuilding. Besides, I don't really need another 45cc saw.
Thanks to all for the advice. Next time I'll check compression and examine the piston first! O

Bingo- there's your problem.

 

[Bob Hedgecutter]

Willing to bet the cylinder could be cleaned up- just a new piston and ring and repair whatever caused it to lean up and burn out (plastic manifold clip clamp?)
Hope you didn't pay much for it?

 

[Captain Bruce]

I have removed the spark plug several times to find that it was wet. Using compressed air I blew out the cylinder and dried off the spark plug and tried over. It certainly has been flooded, but that doesn't explain all my problems. A sheared flywheel key certainly might. I'll have to check that out. Thanks!

How many spark plugs have been tried?

 

[Overlooker]

How many spark plugs have been tried?

2, including a brand new one.

 

[Bob Hedgecutter]

2, including a brand new one.

Not to mention the fact- spark was never really in question and not even if you fused two good plugs together can you make up for low compression.

 

[Overlooker]

Hope you didn't pay much for it?

I'm sure it's worth what I have into it as a parts saw, based on recent completed sales on that big internet auction site. I think I'll let someone else rebuild it as I have two running Stihl 025s and an ms250. O

 

[Bob Hedgecutter]

I'm sure it's worth what I have into it as a parts saw, based on recent completed sales on that big internet auction site. I think I'll let someone else rebuild it as I have two running Stihl 025s and an ms250. O

Yeah but those things are Stihl's!