372xp problem

[owain038]

Just had a 372xp dropped to me. Customer said it was running fine, recently had "engine changed" which he later said was engine and crank replaced. Came in for a coil replacement as the original plug boot had some off and the wire was damaged. Put a new OEM coil in, but no sign of any life. Good bright spark, getting fuel as plug is wet, compression tested at ~130psi (at sea level and also a cheaper compression tester).

Tried new plugs, drop of fuel down the cylinder, decompressor in/out, sprayed soapy water on it while compression testing to check for leaks and no sign of life at all...

Any further suggestions as it's doing my head (and shoulder) in

[Gary Prentice]

When you say new plugs, do you mean brand new, out of the box new? I've had 3 out of a box that didn't spark at all.

 

Maybe I'm reading it wrong, but are you actually getting a spark? 

 

I've had plugs that spark outside the cylinder, when tested, but then didn't appear to spark under compression. 

For testing I'd always use a plug from a good running saw - just for elimination purposes. Then if it still won't attempt to fire, even to cough the problem's elsewhere. Sheared key or something like that.

[owain038]

When you say new plugs, do you mean brand new, out of the box new? I've had 3 out of a box that didn't spark at all.
 
Maybe I'm reading it wrong, but are you actually getting a spark? 
 
I've had plugs that spark outside the cylinder, when tested, but then didn't appear to spark under compression. 
For testing I'd always use a plug from a good running saw - just for elimination purposes. Then if it still won't attempt to fire, even to cough the problem's elsewhere. Sheared key or something like that.

Sorry, yeah I'm getting good spark, have used new plugs and taken plugs out of my own saws with no difference...
Didn't think to check the key actually, will check that soon

[Stubby]

Comp is a little low I would say .

[owain038]

Just got an update
He said "it's been a bitch to start hot and when it runs out of fuel since the rebuild"... He also said the rebuild wasn't expensive so I'm guessing crappy parts used and compression is too low

[owain038]

Found his problem, cheers for confirming low compression fellas

[Stubby]

2 hours ago, owain038 said:

Found his problem, cheers for confirming low compression fellas

Probably re built it without fixing the problem that made it nip up in the first place . Don't do that again ! Check for an air leak from somewhere . Also don't use old fuel .

Edited November 9, 2019 by Stubby

[peatff]

That top end doesn't look like a Husqvarna, the cylinder finish is dog rough. I've never had a bad straight from the box NGK plug yet.

[Stubby]

10 minutes ago, peatff said:

That top end doesn't look like a Husqvarna, the cylinder finish is dog rough. I've never had a bad straight from the box NGK plug yet.

Funny you should say that . I have . just the one in about 50 years . That's why it took me so long to twig it . I did not even consider a new NGK could be duff   !

Edited November 9, 2019 by Stubby

[owain038]

Probably re built it without fixing the problem that made it nip up in the first place . Don't do that again ! Check for an air leak from somewhere . Also don't use old fuel .

My thoughts too, while spraying soapy water at the decompressor didn't product any bubbles I'm not convinced it was sealing up, as apparently the old was reused on the new cylinder, and the crush washer isn't replaceable on them so guessing that didn't seal up properly and produced an air leak.

He's deciding whether it's worth while repairing or not... Might have a cheap 372 on my hands if I'm lucky [emoji1787]