Lost a few MPH and RPMS???

[ramairta1]

Hey guys...
I can not seem to figure out where my mph and rpms went.

I have a 5.7L Volvo Penta GS and a VP duopro. When I first got the boat last year it ran smoothly to about 4800-4850rpms at wide open. Trimmed just right I would see 60-61 on the speedo.
I've noticed this year I am only seeing about 4500-4600 rpms at wide open. Now on the speedo I am only seeing about 56-57.
My VoloPenta is carburetored (GS model) as it is rated to run between 4400-4800rpms (thats what is reads on the engine sticker and in the manual)

I looked at my throttle cable and it appeared to be opening 100% when my shifter is all the way down. I am going to double check it again. I did a tune up at the start of the season, plugs, cap, rotor, fuel filter.

I did notice that early this season I picked up a couple small dings on my duopros. The front pro has a small knick and the rear prop also has a small knick, Nothing major at all, but a couple knicks no doubt.
Is it possible that the knicks on the prop could throw it off a bit and I am loosing a couple hundred RPMS?
Anything else to check?
thanks in advance...
Chris

 

[Don S]

Re: Lost a few MPH and RPMS???

Sure the prop dings could do it, especially if the small ding actually changed the blade shape a bit.
Get the props fixed, then look for other problems if needed.

Or, you can get a head start by checking out everything in this list.
http://forums.iboats.com/showthread.php?t=295070