compression test - whats going on!?

[texas_salt]

Johnson 6R69M 6HP 2 cylinder

Just rented out a compression tester from O'Reilly. Swallowing all my pride on this one.

1. While cold. Removed both plugs. Removed boots. Hooked it up. 4 pulls. 0 Compression.
2. Made sure the two valves on the tester we're all the way in. 4 pulls. 0 Compression.
3. Took out the valve at the end of the compression tester (not even sure if thats correct). Oh well. 0 Compression anyway.
4. Put a plug in, checked other cylinder. 0 compression.


This motor CAN start and run (but dies). Weeks ago, I ran it as long as I wanted. This cant be right.

0 compression = zero running, no?

It has to be something stupid. What could I be missing. Carb is on good (new gaskets). I cant think of what else could be off/loose thats causing 0 compression, other than a broke tester.

Hopefully one of you can answer while I continue researching. I've read 50 "How To's" and I cant seem to find what im missing.

 

[F_R]

It can't run with 0 compression. My money is on a broke tester. What valve did you take out? Did it look like a tire valve? That must be in there, and no it isn't a regular tire valve.

 

[texas_salt]

I took out the valve at the end of the tester. (not the release valve by the gauge). Looks like a tire valve. Blue ring.

 

[texas_salt]

Was the tester. Went to autozone and theirs works fine.

Unfortunately im looking at 60-70 on each cylinder.

 

[sutor623]

Was the tester. Went to autozone and theirs works fine.

Unfortunately im looking at 60-70 on each cylinder.

For a pull start motor, 60-70 is acceptible, IMO.

 

[texas_salt]

For a pull start motor, 60-70 is acceptible, IMO.

Yeah im kinda reading that, especially for old motors. As long as both cylinders are in the same compression range its "ok".

Despite rebuilding the entire ignition, one wire isnt firing, so about to dive into that.

 

[F_R]

Was the tester. Went to autozone and theirs works fine.

Unfortunately im looking at 60-70 on each cylinder.

That's good for a 6hp with a window shade recoil starter. Especially if you are limiting yourself to 4 pulls. Keep pulling till the gauge doesn't go up any higher.

 

[Crosbyman]

70 is what I got on a 4r71 and it works fine...