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I have a 2001 Yamaha 200HP HPDI with 700 hours. I did a compression check and my lowest cylinder reads 100 psi and the highest being 107 psi. When I perform the compression check all spark plugs are removed but the throttle is at fast idle (due to the starter can't be engaged with the motor in gear and full throttle). Even though I am within ten percent of each cylinder the compression seems too low. I consistantly used ring free additive. I have also used Yamaha combustion chamber cleaner spray to achive a different result, but the test out come is the same. Does anybody know what a normal compression check range of a 200 HPDI?
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You can advance the throttle in neutral by depressing the center pivot point cover on the throttle lever. Push in on that cover and you will feel a button being depressed. That button disengages the gear shift cable and allows you to advance just the throttle cable as much as you want. Try doing the test again with the motor warmed up, the plugs removed, and the throttle plates wide open. You should see 115-125 psi in each cylinder.
Mike ....... Miami, FL -
The compression may seem low, but how does the motor run? I would not worry too much unless you are seeing a drop on the top end or the boat won't plane off. 700 hours is not exactly new, but it could be better. Just for comparisionI have a 1987 200 with 1200 hours and compression is 110 - 120 psi (cold and dry compression test). If your motor runs good and you are not looking for every HP, just run it.
D-Comment
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Mine has 95 low and 105 for a high, Does that mean I have a problem?Comment
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I think your engine is alright Brewski. I'm in the process of rebuilding my engine (spun the main bearing, nothing to do with compression). I'll let you know the compression result is after new rings/pistons, etc.Comment
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Thanks, I have been wanting to know what the #'s are on a new one. Sorry to her about the bearings.
BruceComment
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