Compression test what's good and what's bad

Arborist Forum

Help Support Arborist Forum:

This site may earn a commission from merchant affiliate links, including eBay, Amazon, and others.
If a saw has been sitting a long time what's the best way to go at getting a good reading. If you add oil it will be high. But if its dry I could be low
Run it, then test the next day. If running is not an option you'll just have to take the facts into consideration.
 
Should the valve be in the adapter or just the bottom of the hose I looked at a fee different ones today all automotive ones. It's all I could find
 
Should the valve be in the adapter or just the bottom of the hose I looked at a fee different ones today all automotive ones. It's all I could find

At the end of the hose... you don't want to use any adapters. Watch donyboy in this clip. He's using an Innova 3614 and you can see the tip of the schrader valve sticking out from the hose.

 
I notice in my tractors that seafoam in the fuel system and crankcase oil will free stuck rings and reseat stuck rings. A engine that’s been sitting for a while can use seafoam as an upper lube for sticky valve guides too.

I wonder if seafoam will reseat rings in chainsaws.? I don’t expect it to be a engine rebuild in a can but if it raises the compression enough to put off rebuilding for a while.
 
I notice in my tractors that seafoam in the fuel system and crankcase oil will free stuck rings and reseat stuck rings. A engine that’s been sitting for a while can use seafoam as an upper lube for sticky valve guides too.

I wonder if seafoam will reseat rings in chainsaws.? I don’t expect it to be a engine rebuild in a can but if it raises the compression enough to put off rebuilding for a while.
Seafoam, just use Kerosene! Fix in a can makes me :laughing:
 
Ive got a half dozen various brand compression testers, every one reads different when compared on the same motor.
I don't think there's any standard of accuracy with these things.

When tested various saws I've got I get some that read high and others that won't read at all yet they run and cut fine.

My 90's 029 Farm Boss runs great, yet shows less than 50 psi on the gauge. My 036 which feels like its got very low compression
reads close to 160 psi, and my MS271 Farm Boss feels like its got too much compression in that the rope is severely hard to pull and hang on to, yet it reads only 120 psi. My vintage 032 reads 145.
I've got a Mac 10-10 which reads 180, and a half dozen old Homelite Auto 150 saws that read only 90 to 100 psi, yet all run and cut fine.

All of my comp. gauges are Snap On, Mac, Matco, OTC, and one Sears The one Snap on kit is a dedicated small engine kit with extra small hose ends to fit tiny engines.
My MS271 is so hard to pull I was concerned something was wrong with it when I first got it, it nearly rips your knuckles out just trying to hold onto the recoil handle. Yet it doesn't test very high on a gauge. Its got very little use and likely isn't even broken in yet. The dealer told me it'll get better with use.
It sits most of the time because I hate having to start it. I've actually strapped it down to my tailgate to start it it pulls so hard. I've got an older Husky 288 that's the same way.
 
Rented a tester from auto zone it was brand new and has the valve in the bottom. I tested 3 saws I just picked up for $10 a saw . Poulan 3314 # 1 read 140 poulan 3314# 2 read 150 and poulan woodshark was 150. Is 140 low. All the saws need fuel lines so I haven't ran them yet. Got them cause I like to tinker and they were cheap.
 
I purchased two brand new Husqvarna compression testers. They can’t be wrong right.?
 
Hoses are for hosers! ;)

155300380.C5nAvAWj.Mercuryon2165.jpg
 
Someones gonna ask about it, so I'll answer it first. The stuff on top isn't metal fines. That's ashes from a fine Lucky Strike cigarette back from when I used to smoke. :(
 

Latest posts

Back
Top