Looking at a Grady with a '99 Yamaha Saltwater Series II 225hp motor and the compression numbers are 103-107. While consistent, this seemed a little low to me. Any thoughts? Motor seems to run fine.
Its a 14 yr old motor those numbers arent that bad if the motor runs good. A newly rebuilt remaned head I believe is around 110-120psi(+/-) as long as there all withing 10psi Id say go with it. The price is right and its what your looking for pull the trigger. you have to ask yourself alot of questions like how many hrs, how much am I gonna use the boat, what am I gonna be doing with the boat offshore/inshore/lake, if the motor goes bad will I be able to get it back to land. Will it be cheaper to spend a little extra on a better motor and boat that will be more dependable, theres alot to buying older motors but if you feel comfortable and its a deal go with it. #my2cents
2503 Trophy
W/ Merc 115s
Thanks for your input. I’d say I’m trying to get 3 yrs out of it before repowering. Strangely no hour meter on the motor. I’m guessing at least 750.
Consistency is key in that test. There are a ton of variables that can cause a lower reading, #1 being the gauge itself, cranking speed, throttle position, temperature, etc. If it really concerns you, pull the plugs and use a bore scope and look for vertical scoring and excessive carbon. You can test 1 cylinder then spray some wd-40 or similar in there and immediately retest. It will temporarily seal weak rings. If comp picks up 20 psi I would be concerned.
You are probably ok. The OX66 is a beast. Just maintain the O2 sensor.
Hydra-Sports 22 Bay Sport
225 Rude
Thanks for all the input