Should piston be super tight in cylinder?

[Nemesis98]

Hi everyone,

I have a 1989 85 Force engine, and i am replacing the piston in #3. I have everything all set and ready to go - ordered and assembled a standard size piston, rings etc. When I go to put the piston in the cylinder - it's VERY tight. Hard to get in, but once it's in, it's in, and still very tight. Should it be that tight? No changes to the cylinder other than a quick honing to smooth it out.

 

[Frank Acampora]

Re: Should piston be super tight in cylinder?

NO! The piston should be wiggle loose in the cylinder. Rock the others back and forth to see how much it actually is. This is necessary to account for heat expansion. Too tight and it will seize in the bore the first time you try to run it.

Pull it out and remove the rings. Put just the rings into the cylinder and see if they have about .016 end gap. If not, they may be .010 oversized rings that were inadvertantly packed with the piston. If the piston itself is tight in the cylinder, You may have gotten an .010 oversized. With a little wear of the cylinder, and honing, it is possible it may fit--but tight.

 

[Nemesis98]

Re: Should piston be super tight in cylinder?

Thanks for the feedback - I didn't think it should be that tight - it should pretty much just push in smoothly, right? I took it out and will see what's up. I though there was a 'STD' stamped on the box, but that doesn't mean an oversize wasn't put in it! Will have to order another one and try again. Oh well, no boating for me this 4th of July weekend (unless is paddle-powered in my canoe)