I have a 2007 prodrive on a 1754 prodrive boat. It only has a 105 hrs on it. It was the duck opener this weekend and my boat seemed slower than usual. About 15-16 mph. @ 3500 rpms. I carry about 800 pounds which includes just two people. Wondering if I need to see if the valves need adjusting and new head gasket. The boat usually runs pretty good. My prop isn't brannew but little wear. I was just wondering olpeoples thoughts and options. I know about weight distribution.

What's it doing without the load? That will tell us more. If you normally run faster at higher RPM's with the same load, then, yes; something is wrong. Don't know what kind of hull you running, either. If your prop was wearing, you would be seeing higher RPM's.


Most liberals seem to suffer from the same mental condition....it's called stupidity!

It's a 36 pro drive going 15-16 mph. Def something wrong. Check everything. Clean carb. Fuel lines. Fuel tank. Valve lash. Etc

if its a 2007, then you have an older block like I use to have. It a non CDI engine.

Couple things:
1) What kind of rpms do you get out of water? May nee to adjust governor
2) depending on rpms OOW, you may have leaking valves.
3) you could also have one main jet plugged with some trash. Have seen this also.
4) what do plugs look like?
5) do you need to adjust your throttle linkage? Is the butterfly opening all the way open?

Like Troy mentioned, the more details you give, the quicker it can be narrowed down.

Had a guys perform a leak down test he said it was @ 5%, which he said was good.

Is that good? Otherwise there was adjustment needed on the valves

First question: Did they do the test at temperature?

Second question: 5%; was that the difference between the two cylinders? Or, was that the percentage of air lost in each cylinder?

Less than 20% variation between the two cylinders is Briggs' standard for variation acceptance. You really don't want to have any air loss...but loss can be expected. The thing with leak downs and air loss is, you want to identify the source of the leak. Listen to determine from where the air is leaking. Then diagnose from there as to whether intake valves, exhaust valves, rings, head gasket, etc...need to know what is leaking. 5% loss is not much...but it has to be put in perspective...what was test pressure, how long, what size orifice, etc.

That probably didn't help you much! LOL


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When you said there were adjustments needed on the valves....what were you referencing? They did the leak down and heard leakage through the carb and/or exhaust....so, they needed adjustment? Valve lash needed adjustment? Can you clarify a bit what you meant?


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FYI- leaking valves don't affect RPM, they just rob power

At 4100 OOW RPM, your governor is set pretty low- you can turn it up to ~4250 or where it starts pulling up your idle.

If the leakdown is less than 5%, then valve leakage is probably not the problem. As long as compression is fine, your motor should run fine. Valve adjustment shouldn't drop you to 15MPH, what is your normal speed running with that load?

Your RPM under load is low, is the motor running fine but just not getting to RPM or is it running rough?

The motor doesn't run rough. I put a new prop on it was wore more than I thought. I usually get 2 seasons out of one but must have been a rough one last year;). Anyway I've never GPS until I new I wasnt getting on step in deep water. Which was 12-15mph. Like I said I carry a pretty big load 800 or more so I suppose that with a slightly wore prop she just couldn't bite. I'll test after this weekend.

I guess another question just for kicks...what kind of compression numbers were you getting on the compression test?

Stock, my '12 PD was hitting 130/135 psi.


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The guy didn't do a compression test. He said the leak down was so good he knew my compression was good.

If you roll an intake lobe on a cam, leak down will still be fine, but compression will be shit on that cylinder. That's not the only variable, but it's one of them.