so when i do a compression test do i pull a plug put in the tester and let the engine run normally on 3 or just do it cold with the starter or hand turin it or what
- posted
19 years ago
compression test
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- posted
19 years ago
All 4 plugs out. Hold throttle & choke open (just to let air in). Use starter to crank several revs.
Oh...you'll need long arms to reach the Ignition key...
Unless you've already had the plugs out before, consider that there is *some* risk of one of them stripping threads out of the head:-(
I always weigh this factor when deciding whether a compression test is really needed.
You can get a fair idea of compression just by turning the crank pulley by hand. If you turn it
2 revs, you will hit all 4 compression strokes.Speedy Jim
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19 years ago
Turn over with starter at least three compression strokes of that cylinder, compare all four. The thumbrule says compression within 10% of each other.
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19 years ago
Last summer when I checked mine, I was getting fairly consistent across all cylinders, but only about 125 PSI instead of a nicer 140 PSI... How bad is that? I'd love to have the max. power I can get but I have to weigh it against disturbing an otherwise smooth running motor.
It's my original 40 HP 1200 motor, but with a Sears rebuild pist/cyl/rods/valves/bearings upgrade done years ago that supposedly turned it into a 1300 cc motor in the process. I remember being able to chirp the tires, but back then I had bias ply on the back, not the current radials... is that a crucial difference perhaps?