200 hpdi compression. Good or no good

[Kn362004]

Picked up a scarab powered by a 200 hpdi. Believe it’s a 2007-2008. Had it ran to assure there were no knocks, leaks, and tell tail works. All were fine. Bought the handy compression tester due to the fact that the boat had been sitting for about 2 1/2 years. These were the results. Low at close to 105 and high at about 118-119. Since the ones upwards of 120, I feel they all should be in the same vicinity. Just looking for an experienced thought on wether there may be a problem and what should be done from here. Thanks I’m advance!

 

[dingbat]

Within 10% is the quoted norm
119*0.9 =107

You can run some engine tuner through it to see if you have stick ring(s). Otherwise, your options are a rebuild or run it until it dies and start over

 

[Kn362004]

Oh boy…can I run some of the tuner while she’s on muffs a few minutes at a time a couple times and recheck? Or is that something I’m going to be WOT here and there for? Only worry is if rings are stuck and I’m out blasting around and one of the rings break, I’m really screwed.

 

[dingbat]

Oh boy…can I run some of the tuner while she’s on muffs a few minutes at a time a couple times and recheck? Or is that something I’m going to be WOT here and there for?

You run tuner at idle. Let it sit, preferably over night, then put it in the water and run it hard to blow things out.

Make sure you add ring-free to the fuel per the manual. Good VST maintenance is a must with these motors

Only worry is if rings are stuck and I’m out blasting around and one of the rings break, I’m really screwed.

Ran twin 150s for a guy for a number of years. Good engines but are picky when it comes to fuel and maintenance.

 

[boscoe99]

You are well above Yamaha's minimum compression specification for that model.

You can try some ring free for a period of time, or a decarbon treatment, to see if the pressures rise, or become closer to one another. But if the motor starts, idles and runs well it should not be of concern.

 

[Kn362004]

Thanks for the insight fellas. Going to run ring free at 2 ounces per gallon for a few gallons then run it at the normal rate thereafter. I’m seeing a lot about these being fuel sensitive, is that an octane sensitivity? What’s the best fuel to run to try and keep away from fuel related issues?

 

[Kn362004]

Update. She rips