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-   -   2 day 2 stroke compression test (http://www.classicseacraft.com/community/showthread.php?t=21617)

CaptSeaCraft 05-17-2010 08:24 PM

2 day 2 stroke compression test
 
So I borowed a a compression gauge from a friend yesterday and checked my Johnson V4 90HP motor's compression.I never have since I got my SF18 8 months ago and thought it would be a good idea anyway.I checked it yesterday cold and with closed throttle.it was a dead even 115lbs. on the left bank and 120lbs even on the right.I then read its best to do a simploe de-carb on all of the cylinders and do the compression check with a warm motor and throtle wide open.I came home at lunch....warmed up the Motor and pulled the plugs.I shot the cylynders full of Quicksilver engine tune/cleaner and ran it around a bit shooting it full numurouse times to make sure it was getting on the whole cylinder.I did a last dousing of the cylinders and went back to work letting it set in for the last 4 hours.Well I got home.fired it up and boy did she smoke.after 5-10 minutes she was running normal again so I shut her down and went about checking the compression one more time.engine warm,wide open throttle.tistime I got 120 lbs,118 lbs,125 lbs,and 125 lbs.
From my understanding..10% varience is acceptable and less is even better.the lowest cylinder with 118lbs has a estimated 5 1/2% varience from the others......for a 1985 motor this seems pretty darn good.seems like she ought to run for a god long time with good care to keep her healthy.Just thought I'd share the outcome since it was news to me about the de-carb,w.o.t and warm engine to get a accurate 2 stroke compression reading.

Old'sCool 05-17-2010 10:01 PM

Re: 2 day 2 stroke compression test
 
Keep up the decarb. I use SeaFoam in both of mine.

Blue_Heron 05-20-2010 07:03 AM

Re: 2 day 2 stroke compression test
 
Quote:

...I use SeaFoam in both of mine.

Me too.


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