1998 Yamaha 225 saltwater sereies ox66 what should I have for Compression?

69airwolf

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Jun 15, 2011
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Re: 1998 Yamaha 225 saltwater sereies ox66 what should I have for Compression?

anyone ??????
 

99yam40

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Re: 1998 Yamaha 225 saltwater sereies ox66 what should I have for Compression?

Could be a little low, but maybe your gauge or your method of checking.
As long as they are even across the cylinders then it should be fine
 

elalfre81

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May 28, 2015
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please I need to know because I just bought one yamaha saltwater 250 hp 98. and the compression is between 110 and 115
 

magictouch

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May 6, 2012
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I just rebuild 2000 Yamaha 250 OX66 and I have compression 92 all around. Runs good but I need to know if this is normal
 

M.A.CCruiser

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May 14, 2012
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The important thing is that they are within 10% of each other. Gauges vary drastically.

Did you warm the engine up before you tested the compression? Was the throttle at WOT or closed? Were all the plugs removed or just the one on the cyl you were testing? All of this can have an effect.
 

rjcamel2355

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Apr 22, 2015
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I have around 105 on my 99' ox66 200HP 3.1L EFI, and it runs idles and performs flawlessly. As mentioned each gauge reads differently, within 10% is the important thing. If you think you have an issue, you can always wet and dry test. Wet testing mine (teaspoon of oil in the cylinder) has about 108PSI, so I'm not concerned about a ring issue, or anything of that sorts. These motors are amazing, keep clean non eth fuel in them, ring free/seafoam/whatever you prefer, clean the O2 and drive them.
 

GA_Boater

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I just rebuild 2000 Yamaha 250 OX66 and I have compression 92 all around. Runs good but I need to know if this is normal

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