1988 25hp Mariner compression?

[Mas]

A friend of mine gave me a '88 25hp Mariner. I spent the afternoon cleaning it up...pretty good shape. The PO said it ran great...etc.

I did a compression check and got 105 Psi on both cylinders...great it is even...but what is the norm for this motor

I'm still working on spark...nothing yet. Unfortunately, it is not electric start...hard to get fast rpm with the rope!

Any advice or suggestions?

Mas

 

[flyingscott]

My 87 cold will be 120ish psi. Make sure the kill switches is in the run position. What is your serial #

 

[Mas]

Serial 0B153079

The motor has been sitting for a couple of years...rings I'm hoping will loosen up.

Mas

 

[Texasmark]

Serial 0B153079

The motor has been sitting for a couple of years...rings I'm hoping will loosen up.

Mas

Do a google for "decarb". Perform the function. You won't be sorry. It's here in the archives too but googling is faster. Then keep SF in your gas mix. It will keep the problem from reoccurring. I learned about it here and haven't been without it since hearing about it.....and yes it will impact compression on your outboard and any other engine you have sitting around carboned up.......I have a 1963 Ford 2000 diesel tractor with 3700 original hours that I did a number on it and it all but quit smoking....it wasn't bad rings, they were just carboned up and couldn't seal properly......and an old 4 stroke 3 hp lawn mower, and a 2 stroke Mantis rotor tiller, and an original 2 stroke Weed Eater brand string trimmer, and a 2 stroke Poulan chain saw......that I can recall off hand.