300promax Exhaust Issue????

[snosuxs]

I had a previous tread 300 PM loosing power!!!! I had the engine on the computer today--- I have a 21' Hustler with a 300 promax, everything checks out fine, But hard to plane off!!!!! A friend of mine dropped off a 24 bravo to try out, it couldn't even get on a plane-----It was like a 9.9HP--- I went back to the dock and installed a 23 Throphy and was able to get on a plane!!!!! IT almost seem that the exhust is clogged!!!!! I called the mercury rep, He eleated to a few cases where the sleves turned in the block closing off the ports??????? Hey I'd love to hear some insight

[fastskeeter]

there has been issues sleeves spinning inside the block. real easy to check, pull heads, rotate flywheel and look and the ports in the sleeves vs the areas in the block that were machined to match the ports in the sleeves. did the bravo have any exhaust relief holes in the prop to help it spin up?

[Still Crazy]

there has been issues sleeves spinning inside the block. real easy to check, pull heads, rotate flywheel and look and the ports in the sleeves vs the areas in the block that were machined to match the ports in the sleeves. did the bravo have any exhaust relief holes in the prop to help it spin up?

Not to suggest that you might not have an engine problem, but I sometimes run a 26 Bravo lab on my 21' Superboat/300X Promax. My prop has large 1" ventillation holes and it is still a bit sluggish coming out of the hole. I once tried a bone stock 26" Bravo with no ventillation holes and the engine bogged down so much when I punched it that I initially thought I had stalled the engine!

[time warp]

My money is on nothing being wrong with the motor, you need to put vent holes in the hub of the Bravo Prop if you are going to use it on an outboard. You aren't the first person with this problem, there have been other threads on it in the past. Here's one,
http://forums.screamandfly.com/forums/showthread.php?t=131265