Martin 20 compression?

[Buccaneer]

Yesterday I tried starting the little Martin 20, 2.3 hp motor I’m going through.
Before I tore it apart it tested at 75 psi compression. I reused the original
rings, but did give the cylinder a very light hone with a ball hone.
Honing showed a little cylinder imperfections, but not “bad”.

I could only get it running yesterday “out of water” and using a drill.
I retested the compression today, and it showed 100 psi using the drill,
and 90 psi with three rope pulls.
Surely 90 psi should make a runner….. or not?
I’m not used to working on this little of outboards. What’s considered good
compression on these? I believe it has a 1-9/16″ bore.

I did discover today that I had the old original J-8 plug in it, and only
finger tight, so I changed it out with a new J-8C, but I have not
tried to restart it yet….. weather is gloomy.

Prepare to be boarded!

[Tom]

Have you tested the condenser with a proper tool? The WICO standup condensers are notoriously bad.

T

[Buccaneer]

Tom wrote:

Have you tested the condenser with a proper tool? The WICO standup condensers are notoriously bad.

T

I replaced with a electronic’s capacitor. It has nice blue spark.

Prepare to be boarded!

[Buccaneer]

Yesterday when running it I got my glove between the mag advance lever
and flywheel. Mag then slammed the throttle shut and it was “out of sync”.
I thought it was just the little set screws locks that slide out of whack on
the linkage, but found out today it broke the head off the throttle plate
screw, and the throttle plate was flopping loose inside the carb. Luckily,
the brass head did not make it through the poppet valve!
I put the hand lever on the mag plate advance today, and did not wear gloves, lol.

Running wide open here. It will only start in the water with the drill. Will
rope start when it’s “out of water”. Guessing my 90 psi compression
isn’t quite enough for this little motor. It likes a quick choke to start,
even when warm.
https://youtu.be/Ul2AYWh7dGw

This is about slowest I can get it to idle down
https://youtu.be/2nLJ9AdtgKg

Prepare to be boarded!

[Bob Wight]

Seems to run pretty good – hope you can resolve the starting issue. Lucky that screw head didn’t get sucked in!!

Bob

1937 Champion D2C Deluxe Lite Twin
1954 Johnson CD-11
1955 Johnson QD-16
1957 Evinrude Fastwin 18
1958 Johnson QD-19
1958 Johnson FD-12
1959 Johnson QD-20

“Every 20 minute job is only a broken bolt away from a 3-day project.”
"Every time you remove a broken or seized bolt an angel gets his wings."

[fifty20ne]

Maybe try a higher
Oil mixture if you
Still suspect compression
Problem! More oil
Added to gas mix
May help?

[Buccaneer]

fifty20ne wrote:

Maybe try a higher
Oil mixture if you
Still suspect compression
Problem! More oil
Added to gas mix
May help?

I was just thinking about the “oil” as I was re-watching the video,
and not noticing any blue smoke. My can was labeled 16-1,
I sure hope it has oil in it!

Prepare to be boarded!

[Author]

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