RPMs no speed... help?????

[QC]

Re: RPMs no speed... help?????

OK, then I can maybe buy the tach story. Seems like there should have been a noticeable lack of noise to go along with the tach reading. Just need to test it with a good tach though to verify.

 

[KermieB]

Re: RPMs no speed... help?????

How come nobody asks him what pitch prop he's using?

jarheadtex.... what pitch prop are you running?

 

[Jungleboat]

Re: RPMs no speed... help?????

I've had a spun prop and could indeed get on plane most of the time, just every now and then she'd rev up high and actually slow down a bit.

As my prop was worn I just got a new one and had the old one re-hubbed as a spare.




JB

 

[QC]

Re: RPMs no speed... help?????

How come nobody asks him what pitch prop he's using?

Because it is so far off it is not even in play yet . . .

 

[jarheadtex]

Re: RPMs no speed... help?????

I have a 14x19 prop. I think it is the stock prop. Im taking it out this weekend ,... so i will be back sunday with more .....

 

[jarheadtex]

Re: RPMs no speed... help?????

so i put an auxillary tach in. It turns out the stock tack is reading about 600 rpm higher than the new one at an idle so i imagine that could double on WOT.

 

[oops!]

Re: RPMs no speed... help?????

there are a few causes of this.....a really weak motor. a spun coupler, and a bad hub.

double check that coupler.
the coupler is the sacrifical lamb of the drive/ motor.

and the hub is the lamb before the drive.

if all checks out.....have a compression test done.

a rebuilt prop with a hub kit is around 130 bux for alum.

 

[RickJ6956]

Re: RPMs no speed... help?????

Telltale signs of a spun engine coupler: Metal filings in the bilge where it meets the transom. If you can't climb back there to inspect it, use a mirror.

Another way to check is to pull the drive unit. There will be metal filings on the spline. Use the proper grease when you put it back in.

 

[QC]

Re: RPMs no speed... help?????

It turns out the stock tack is reading about 600 rpm higher than the new one at an idle

His tach is waaaaaaayyyyyyyyy off. I don't think any of the initial post info is valid. It appears the OP was reacting to the tach and not to the way the boat was performing.