Compression checking today

[a. palmer jr.]

I was checking compression on a couple of good running McCulloch saw and got a surprising reading. I first checked my 10-10S which runs and starts great but only registered around 100. I checked the comp. release and it seemed okay. I put the spark plug back in and it was really hard to pull the rope like it had a lot of compression so I'm perplexed. I would have thought the saw was worn out but I tried my Pro Mac 55 and it did the same thing. I checked the 55 warm and the 10-10 cold. Both saws seem to have lots of power, just wondering about the low reading. Not too long ago I used this same gauge on my 610 and it showed close to 200. Opinions please..

 

[Adirondackstihl]

What kind of gauge are you using?

 

[FATGUY]

check to make sure the schrader valve is tight. If it is, it may be time to borrow another gauge and do a side by side comparison. Then again, maybe those saws run fine at that compression....

 

[a. palmer jr.]

Uh..I found it. My stupid mistake. When I checked a 3rd and 4th saw and they all showed the same I gave the gauge a good look and found the problem in the deep well adapter I was using. The threads in it were too long and wouldn't allow the gauge hose to seat against the spark plug hole. I checked my 25 Poulan without using the adapter and it showed 150psi. As soon as this blizzard is over I may go out and check the Macs again. Thanks for your input.

 

[a. palmer jr.]

What kind of gauge are you using?

It's an el cheapo. I don't have any high priced stuff around here.