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I have a 1971 55HP chrysler. How do I check compression? How much is the tool? I understand there is something you screw in place of plug. Do you remove all plugs together? Is the engine running when you check compression?
I bought my compression tester at an auto parts store. If memory serves it was only $20-30. I found out a couple of things that will affect the compression via tria and error. Of course, there's folks here that tell you in GREAT detail what to expect, but here's what I found:
#1 Only one spark plug at a time.
#2 Don't let the engine start. It should just turn over a few times. I engaged the kill switch so it wouldn't start.
#3 Don't try it with a weak battery. I had a weak battery. Compression showed about 90 on all cylinders. I was very worried. Replaced the battery and compression went back up 120 range. Of course, compression ranges depend on your motor.
#4 Don't forget to release the pressure release button on the compression tool (you will see). You may get a false normal reading on a cylinder that may be low.
The objective in a compression test of a 2 stroke engine is to detect any one, or rarely, two, cylinder that has lost compression compared to the other cylinders.
That means that psi readings need to be close to each other. Most of us recommend within 10%, but 15% is usually acceptable.
Step by step instructions are in about a dozen threads. SEARCH for "compression".
Remove plugs(all) Open throttle all the way hook up tester turn over.Take reading,repeat on other cylinders.Comp should be even or close,within 5-10#
Most force should be around 150# J
Remove plugs(all) Open throttle all the way hook up tester turn over.Take reading,repeat on other cylinders.Comp should be even or close,within 5-10#
Most force should be around 150# J
