Have a Husq 41 that doesn't want to stay running. Haven't torn the carb apart yet but it seems to be getting fuel (plug is wet). Also getting good spark. Tested compression, only around 70psi and looks like some scoring on the walls. So, as the title says, how low is too low?
Compression - How low is too low?
- Thread starter burnt03
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Under 110
excess650
Addicted to ArboristSite
Thats' probably 65# too low.
lambs
Stihl crazy after all these years
I think you'd want to see 120 minimum. But that's just my opinion. It may run with less, but at 70, I'm not surprised it won't run.
excess650
Addicted to ArboristSite
I had one that wouldn't run at 125psi.
cpr
Addicted to ArboristSite
In your case, less than 120, but that's not a rule of thumb if you play in the vintage world.
IF you are using the right compression tester then it shouldn't be running at all.
graybear13
ArboristSite Member
Seems like I heard once upon a time that you need around 120 psi for an engine to run. I suspect that is about as low as it needs to go. Some of the engineering types may chime in and give specifics, but you prolly need to do some wrenching on your saw.
Saw Dr.
Junk Collector
I have several old reed valve saws that will run OK at around 100 PSI. 120 is about the minimum for a piston port saw. There are a few exceptions, but the 41 is not one of them.
excess650
Addicted to ArboristSite
That's encouraging. I picked up a decent looking Homelite C-52 and only see 120psi. It will run with a prime, so likely needs a carb kit and/or fuel lines. What little of the cylinder I can see through the sparkplug and exhaust look fine. It has a distinctive bark to it.:msp_w00t:
naturelover
Tree Freak
I have an old outboard that runs great with 90psi, and is far away from the service limit of 60... 
On the brighter side, ebay usually has piston kits for these saws and at fairly cheap prices.
M
moody
Guest
It's best to rebuild or freshin it up. You're doing more harm than good running a saw that's low compression. It could be a simple replacements of the rings to begin with. As I was always told proactive is more productive than reactive . Dont wait for it die.
Take the muffler off and look in at the piston and you'll have your answer.
sachsmo
Addicted to ArboristSite
With only 70 psi my guess is the rings are stuck, or it really has a lot of transfer.
Seen some pretty ugly bores clean up and run fine with a new piston and rings.
Piston forHusqvarna 41, 141, 142
Seen some pretty ugly bores clean up and run fine with a new piston and rings.
Piston forHusqvarna 41, 141, 142
