Compression

[NaturalLight16oz]

i checked the compression on my 96 25 yamaha. Top was 100 and bottom was 75. What does that mean to me?

 

[Dhadley]

Re: Compression

It means you have a 2 cylinder 25 hp.<br /><br />I just couldnt help myself. Sorry about that! Seriously though, its past the 15 lb difference variation so if it were me I'd pull the head to take a peek. I'm sure the Yamaha guys can offer some more advise.<br /><br />Good luck!

 

[NaturalLight16oz]

Re: Compression

Any Yamaha guys care to help me out?

 

[Boatist]

Re: Compression

16oz<br />I not a Yamaha guy and do not know it we are talking about a two stroke or four stroke. First how does motor run?? If it runs ok I would decarb and check again. Also pull plugs and squirt some auto engine oil in both cylinders and check again. If compression come up this indicates worn ring or stuck rings. If it make no difference then could be a bad or mis adjusted valve on the 4 stroke. Decarb should up stick the rings.

 

[dkondelik]

Re: Compression

What's a Yamaha?<br /><br />Sorry, don't know your motor. Fromwhat I understand, Yammy makes a pretty good machine.<br /><br />All of that said. It COULD be a stuck ring that a decarb can help but I would pull the head and the exhaust cover, and take a look. If it's a 2-stroke, I would guess that you've got a broken ring and likely, the associated cylinder damage.<br /><br />Good Luck<br />HAVE FUN!

 

[NaturalLight16oz]

Re: Compression

The motor is a 2 stroke and has no top end and burns lots of gas.. Is it time for an overhaul?

 

[JB]

Re: Compression

Howdy, NL.<br /><br />Give the engine a thorough decarb treatment and retry the compression. That much drop could simply be caused by carbon stuck rings.<br /><br />Good luck.

 

[NaturalLight16oz]

Re: Compression

can you point me in a direction as to how to decarb my engine?

 

[dkondelik]

Re: Compression

NaturalLight,<br /><br />Do a search in this forum on "Decarb".<br />Lots of info available.<br />SeaFoam (availabale at Napa), OMC Engine Tune (JohnyRude/Bomb), etc, etc.<br /><br />Good Luck<br />HAVE FUN!