Yamaha 130 compression

[klyross]

What would be a good compression range for a '94 and a '01 Yamaha 130 2 stroke?
(I am guessing it would be the same for each motor.)

I am looking at a rebuilt one with 115 psi across all cyls. and another
at 107-110 across all cyls.

Thanks....

 

[JB]

Re: Yamaha 130 compression

Either has good compression, klyross. If they had been tested with the same gauge and technique they might be identical.

 

[klyross]

Re: Yamaha 130 compression

Thanks !!!

I found a third 130. Compression high, but uneven on the 2 lower cyls. 148-150 on the 2 top cyls and 135-137 on the 2 lower cyls. (Interesting that top 2 are the same and the lower 2 are the same. ) I know about the 10% rule and this is right at or slightly below and that compression testers vary, but, supposedly the motor has not been used in at least 8 years and looks great!
What do you think??? Lake testing is out - motor on a rack and I did witness the compression test.
Mechanic who is selling motor says it has not been rebuilt - just some carb cleaning.
Thanks ......

 

[ezmobee]

Re: Yamaha 130 compression

From what I understand, the actual numbers reported by those compression gauges aren't necessarily real accurate but they are consistent and that's what's most important. Anything over 100 is probably pretty good. I'm a little concerned about that motor you are looking at with uneven numbers. It's possible a decarb and a little run time would even those #'s up, otherwise I'd want a pretty big discount on it.

 

[klyross]

Re: Yamaha 130 compression

Afraid you might say that - it certainly reflects exactly what I was thinking. My gut says be careful, my 'want factor' says run time will even them out. Any possible significance to the 2 LOWER cyls being lower(but equal) ? Might they have a tendency for a stuck ring or something that would single them out more than the top 2? (grasping at straws here, I know .... )

Thanks ....

 

[brnschoneck]

Re: Yamaha 130 compression

yes i beleive also as long as the numbers r over a hundred n all identical with in 10% ur good not no good !!!

 

[klyross]

Re: Yamaha 130 compression

Thanks all.
I ended up purchasing one with 140 140 135 135, so, hope it works out for me.
Looks like very low hours, but cover is sun-faded so have some work to do there ...