compression acceptable? 100 - 110 - 100 - 90

[rick 48 cub]

Thanks for all of the feedback. Dispite the fact that it was about 20 deg F today, and that the engine has not run for weeks, I personally thought that the compression numbers looked pretty good. What do you think ?

Something funny happened while I was testing the compression. The same thing happened on each of the 4 cylinders. The Max pressure would be reached after four or five pulses - then even with the engine spinning with the starter - the pressure dropped off dramatically. Whats up with that ?

Thanks, Rick

[Eugene]

I'm assuming that the compression readings are wet (oiled cylinder) readings. Two of the cylinders improved and two dropped - that's highly unlikely.

A guess, the compression tester may be faulty - leaks or is not holding the pressure. I have two types. One holds the pressure until you press a button. The second, you have to watch as the needle (pressure) moves up and down with the cylinder.

The spread is just a little wide. Even with an overhaul the psi reading wouldn't improve very much. I would try the sea foam to loosen up any stuck rings and work the tractor for a while. Then try the compression readings again.

Eugene.

[rick 48 cub]

Hi Eugene,

Actually, I tested the cylinders dry. I could not find my fogging spray.

Rick

[Eugene]

Catsup bottle. Just squirt a bit of motor oil in each cylinder. I think your engine is pretty close to normal. I just wouldn't worry about it.

I was going to mention before. I had problems with my compression tester, the one with the valve to release pressure, when it was very cold - around ZERO in the shop. After I warmed up the shop for a couple of days it worked fine.
Eugene

[rick 48 cub]

Thanks for the similar compression story. I now have found direction. Based on my examination of the cub so far (weak spark/decent compression) I am going to pull the magneto and have it rebuilt and re-magnetized.

Take Care

[beaconlight]

sounds as if you are heading in the right direction.

Bill