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View Full Version : Compression Numbers for BGA's Oceanrunner


Bygracealone
07-20-2009, 06:44 PM
Hey guys, I was working on my motor today (1996 200HP Johnson Oceanrunner) and decided to do a compression check just for the heck of it. Here's what I ended up with from the top down:

98 100
93 102
90 97

I'm not sure how great my gauge is; I noticed some of the rubber seal was getting a bit torn up as I was using it, but it seemed to be working fine as far as I could tell.

Anyway, are these numbers okay?

Thanks!

Steve

macojoe
07-20-2009, 07:41 PM
They say stay 10% to each other, your close to it with that 90
But I had that on a Yamaha one time did a decarb and all the numbers improved and were all with in 5% when done.

But what do I Know??

phatdaddy
07-20-2009, 09:51 PM
was that with a warm motor & the throttles open?

if so, try MJ's de-carb treatment.

Bygracealone
07-21-2009, 07:07 AM
Phatdaddy,

That was on a cold engine and the throttle was not wide open. I didn't realize that was a factor. Is it better to have the throttle wide open to get a more accurate reading?

Thanks.

I will try MJ's suggestion anyway since it can only help.

phatdaddy
07-21-2009, 06:49 PM
BGA, to be honest, i don't know. it's the way i was taught to do compression test. as my wife , the science teacher, would say "lets make this a learning experience". do another check with a warm engine & open throttle's and we'll compare.