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95 response only tacking out 3200 rpms


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My response sitting on the dock will rev out to 4800 rpm's no problem. I put it in gear and take off. It's slow out of the hole and tops out at 38 mph. Revs out @ 3200. So far this season I have put a new carb on it. Complete tuneup: plugs, cap, rotor, wires. Timed it. Taken gas tank out to check screen for clogs. Disconnected throttle cable and powered boat by hand making sure cable wasn't restricted. Also watched secondaries open up @ the same time. Any suggestions out there would be appreciated.

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I did a compression test on it, all cylinders were around 150 the low one was 137 the plug on that cylinder did show some black carbon. The other plugs seem too look ok. I was having a problem with this last season,but I was always relating it to a carb problem. The plug wires are in the right location.

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I did a compression test on it, all cylinders were around 150 the low one was 137 the plug on that cylinder did show some black carbon. The other plugs seem too look ok. I was having a problem with this last season,but I was always relating it to a carb problem. The plug wires are in the right location.

Was it a carbon residue, or was the electrode & insulator actually black? Maybe pull the new plug for that cylinder and see how that one looks.

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Do you have a speed prop on or a power prop on it? Try the opposite prop and see what the rpm's are.

If you have a power prop maybe it's too much and causing prop slip (making it slow out of the hole and low top speed/rpm).

How is it " slow" out of the hole? If you throttle up at a medium pace with no ballast is it slow? Or only with ballast? Or only when you hammer it?

Someone loan him a dif. prop to try!

Where r u located?

Any chance the RPM gauge is wrong?

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Fuel pump? Check the clear line going up to the carb to see if the diaphram is good.(should be free of fuel). Ive seen poor fuel pump performance cause an issue like yours before. The engine will rev up in neutral but underload it may not be getting enough fuel. Either that or how is the velvet drive? Oil good? possible slipping issue?

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I've used the same make and prop size since the boat was new.

I don't want to come off as condescending, but but you implied the prop change might be coincident with this issue...if so, I'd take another look at the prop. Even if the published pitch is exactly the same, the cupping could be enough to be causing the issue. Are you sure the props are exactly the same? If you have the old one, put it back on and see what you get...your new prop could be the same diameter and pitch but with higher cupping which is causing the issue.

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