Compression question.

[leeinnh]

Ok it’s dumb question time. I have been restoring for 20 years. I have asked this question over and over and never get good answers. Folks joke , or sneer, or act like I am
An idiot, ( which I am).

Compression. Is 62 a reasonable compression in an elto pal, Elgin 1.25 hp,
Evinrude sportsman ?

Because that’s all I ever get for readings despite changing testers,
.
Cold engines. Some run well, some don’t, so I look for other problems like the carb.

Is there a magic compression Number that is ok, and if the motor doesn’t run well ,look elsewhere.

I don’t think manuals list that – they list what it might be when new.

I would like to know what is adequate.

[Buccaneer]

No experience on the Elto Pals, but I have two Johnson HD-25’s
2-1/2 hp motors with 65 psi compression, and they don’t idle real slow.
Another with 75 psi, and is a good idler.

Prepare to be boarded!

[collectorinspector]

Pal @62 is about really cool!

Enjoy.

BnC

[Tubs]

Compression readings can vary on
these small cubic motors depending on the unit.
What type or style of tester are you using?

These don’t have an idle circuit in the carburetor so you
need to lean the mixture out about 1/2 a number to get
them to run really slow.

Also the lift of the poppet valve will effect how they run.
To little and the motor wont speed up. To much and they
run like they are rich but leaning out the mixture doesn’t help.
Should be around 3/32. You can use a drill bit and compare
the movement. If it close its best to look elsewhere.

This can also cause one not to idle well.
https://youtu.be/NnDfmCQeoSo

Something else you should be aware of.
https://www.youtube.com/watch?v=cSZO047tTkk

A "Boathouse Repair" is one thats done without having tools or the skills to do it properly.

[Author]

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