RPM concerns on '87 Suzuki 150 supersix

[staunch]

I have a '87 150 supersix on a 18' bass boat that after sinking it and a year of working out the kinks, runs great. My only concern is over-reving of the RPM's. The boat will run 65 mph at around 6500 RPM at about 3/4 throttle, but when i give it full throttle, it jumps past the tacks 7500 RPM limit, possibly 8000 RPM. The boat literally flies at around 83 mph and sounds great, i just can't possibly imagine that it is good to be running at that high rpm's. Anyone got any advice aside from "don't run it that fast?'......lol

 

[Steamboat]

Re: RPM concerns on '87 Suzuki 150 supersix

Wrong size prop and you'll eventually blow up the engine running that fast.

 

[keysrat]

Re: RPM concerns on '87 Suzuki 150 supersix

What is the pitch on the prop you are using? You need to get a prop with a larger pitch.

 

[classic 24]

Re: RPM concerns on '87 Suzuki 150 supersix

you may have a faulty tach. the suzuki has a rev limiter that should kick in about 6200 RPM

 

[rodbolt]

Re: RPM concerns on '87 Suzuki 150 supersix

it was possible years ago to buy a CDI with no rev-limiter. it required the warrenty card to be turned in. check your tach against a known good inductive pick up tach. its possible you have some rectifier issues.

 

[staunch]

Re: RPM concerns on '87 Suzuki 150 supersix

Thanks for the replies. I am running a 3 blade stainless 14 1/4 26 pitch prop. I was thinking that it could be a faulty tach, but it runs so close to true all the way up to wide open. I will have it checked out.