cedarshark
Addicted to ArboristSite
There are some here that feel if the compression gauge does not have "Snap On" clearly visible on the face of the tester, it just cant work correctly. Good luck on your rebuild,I bet the rings help a lot.
What am I doing wrong? Compression testing
- Thread starter rxpx40
- Start date
Help Support Arborist Forum:
There are some here that feel if the compression gauge does not have "Snap On" clearly visible on the face of the tester, it just cant work correctly. Good luck on your rebuild,I bet the rings help a lot.
Not that there is anything wrong with a Snap on gauge I love mine.
I don't believe I would have a way to buy a new Snap On tester even if I wanted one. Aren't they only sold to businesses? Guess I could buy a used one but it might be worse than the one I have.
Guido Salvage
Supreme Saw Whoreder
I found my Snap-On in a pawn shop for $35 plus tax.
You could buy one online from snap on . Im trying to remember who makes them for snap on you can buy one new for almost half the price.
New smaller Stihl saws (171/181/211/251/241) will use the smaller plug size commonly found on some of the trimmers.
Some Chevrolets use smaller plugs but I think they have the same thread size. Old Ford cars used a big tapered thread but doubt if any use it now. I got the cylinder off my saw today and it looked really good, no scratches or anything. Piston looked okay also but ring was stuck a little bit. I took the ring off and used an old ring to clean the groove so I guess I'll just try the new ring and see how it does. I'll put the piston in the bore and make sure the clearance is all right first before I slap it together. Then I'll see what my el cheapo compression gauge reads...
I don't have any new stuff around here, other than parts..
Good enough
, but eventually the new stuff will be old stuff. I just thought I'd throw it out there for future reference of others reading the thread
Then it will fall into my hands...I've never worked on any of the new Stihl saws yet, kinda hope I don't have to...newer chainsaws are getting to be like the newer cars, a pain to work on but nice while they're running..Good enough
Heh, I know everything is bigger in Texas, but I'm fairly certain none of our mountains are that tall. It must be my gauge causing the problem. I picked up a very nice ms390 this weekend. Took down a few dead oaks in my yard, then tested the compression with my gauge. Does anyone want to guess what I got for a reading on a known running saw?
MarkEagleUSA
ArboristSite Guru
38 PSI?
Some of the old Lawn Boy mowers run at a pretty low compression. I think one of mine showed around 90 and runs fine. My chainsaw showed 90 and wouldn't hit a lick..
cedarshark
Addicted to ArboristSite
I bought an 12mm 044 recently that coughed but wouldnt run....blew 80 psi and the p/cyl were perfect in a New West A/M top end kit. Put a used Giladarni OEM p/c on it and it runs great. I didn't even care what was wrong with the New West Kit. I bet it will be new Bud Light cans in a few days.
We have a winner!38 PSI?
cedarshark
Addicted to ArboristSite
A 390 that runs with 38 psi..will wonders never cease. I guess that gauge is headed to the dumpster.
Is that check valve on the fitting that screws into the plug hole....or is it on the gauge? There must be some volume of air in that gauge assembly prior to the check valve which is lowering the compression ratio. Is it easier to crank the engine with the gauge installed that with the sparkplug installed?
