Amy knowledgeable Yamaha folks on here?

Just had a 100 hour service done on my
225 SHO and my compression readings : 1/180,2/165,3/160,4/165,5/175,6/168. Any opinions on whether those
are good numbers?

they are within spec, but fluctuations seem to be maybe carbon buildup. Do you use ring free in the gas?

Ring free with fuel stabilizer and biobor on every tank.

So....was the 100 hour service on the first 100'hours? Or is the motor 500, 600?

If it's the first 100'hours I might be a little nervous, but if it is the same reading and the motor has 600, 700 whatever, is think I would be happy.

I guess what I saying is I'd like them closer if it were mine and a newer motor. But, it is within spec. I think most say within 15% is good and yours are really closer to 11-12%.

Does the motor run smooth? Make good power? Smoke? Make excessive noise?

I think if it runs good and is smooth, I'd worry more about getting bit by fish and hammer down.

289 hours. The motor still runs smooth. I have one of the first run SHO's. I got a letter from Yamaha about 9 months ago informing me that I qualify for a free powerhead replacement until 12/31/2018. The letter specifically said it wasn't a recall. I called Yamaha and inquired whether or not the that offer would be good whether or not something happened to my powerhead and the person I talked to said yes as long as it was by the the date on the letter. I said, that is basically like a powerhead warranty and he said pretty much. Is there any reason I wouldn't wait until the end of 2018 and replace the powerhead at no cost?

I'd question the gauge. I don't know of a single shop or technician that have their gauges calibrated periodically.

I would bet that we have a 1000% better compression gauge than the want-to-be mechanics. I would bore scope the cylinders and do a leak down test. Maybe I need to go back to school on my math as well but 10% has always been the allowable difference.

When was the last time yours was calibrated?

I would do it sooner rather than later. The new SHO motors are hard to find. But I don't know about power heads/parts. I would call a couple of shops near you to find out if the parts are available. Also, if you blow up your motor, do you think they will still off the free power head?

I'd get that PH now. Never know what could change between now & then. Won't have to worry about it failing( reason for PH replacements).

Have a leak down test performed. That will tell you more about the condition of your powerhead.