I have a stage 1 23 mini, with a gear reduction and a big blade. It can rev 5000+ OOW but by myself I can safely run 4300ish in the water and hit 27-28mph. However here lately Ive lost some rpms somewhere. The engine runs steady, no problems, its just like im running less throttle. It isnt opening up. It will spin like a wildcat out of water but in the water by myself Im in the upper 3s, about 4-500 less than what I should. This also reflects proportionately down the line with loads. Where should I start looking? Whats a list of things I could rule out? Thanks for the help.

Compression check and a Leak down test should be first.

Might want to check and make sure that your throttle cable hasn't stretched a bit. I had a Hyper that had a stretched cable and didn't make full power.

That's exactly what I experienced a month ago right before dropping a valve. When I cracked the left head, the valve retainer was in 3 pieces and the intake valve was bent and stuck in the open position. Not saying that's your problem at all because honestly, I do not know what caused mine to do this. However, I lost rpms with the prop in the water and when I brought it out of the water I had most of my rpms back. And then when I would put it back in the water, I would lose almost all my power again.

Don't know what caused it to drop a valve?
Reving a 3500 RPM LAWNMOWER MOTOR to 5000 + would be a good bet Just sayin'

The 5000+ rpm oow is likely the problem. U likely have internal engine issues.

Ive never sat there and done that or had my eye on the the tach when it did do that. All I know is it doesnt sound like its stopping anytime soon when I pump it to 46-4700ish. Its never been held down and gassed.

Has the prop ever kicked up out of the water when u had it wide open? U only have to do that once without a rev limiter to toast an engine.

Vanny23, gear reduction, big blade prop, 4000+ rpms in water and bumping higher occasionally...expect trouble, I'm thinking. I run constant 3500 rpms lately with load and am thrilled. Finally my tach is stable after retwisting the spark plug wire a few extra times.

Heck, stock it ran 4310-4320 OOW and 4100 by myself.

Just the other day I was siitin at the dock waitin for the wife to park the truck and I reached abck and realized that my carb wasn't opening up all the way it was a quik fix my cable just needed to be adjusted a little

How did the compression and leak down test do? The folks on this site can't help you without u giving a little more info.

Hey guys, sorry for the delay. Im trying to track down a leak down tester right now. I hope to get the results back and start walking through this stuff with yall so we can get it knocked out. Im starting to lean toward a gasket leak, its usually got a decent oil sheen/residue below the left head if your looking at it from the back.

There is some old posts on how to make one. Harbor freight has a cheap one if you have one close by, you could grab one from there. May also check your local autoparts store. A lot of them rent stuff out like that for free.

Caleb where are you located...I'm in the Morgan City area and have one I just bought that you could use