2 Stroke 115-Strange Occurence

I have had this boat and motor for five years. Top end fully loaded was always around 43 mph with around 6500 rpm. I took the boat out last week at was running around 48 to 49 mph, and the rpm's were 7000. I cannot figure out what happened. I put some additive in the fuel but I have done that before. What do you think?

[margaritaville]

Change the prop?
How are you getting your Speed? GPS?
If not, I would guess that you have a bad gauge.

If you are truly turning 7K RPM, you will not have the motor long.

Faster Boat

No change in the prop. I have GPS and a gage, the gage always read 2 or 3 mph faster than the GPS. So what I quoted was the GPS speed. I know this boat well and I can feel the difference in speed.

[jb123]

yes your wrist pins wont last long at those rpms....
what year is the motor??

what pitch prop ? as it sounds lil under propped

not sure if your motor has a limiter but it sounds like yours isnt working if so.

Prop Size

It is the original prop that came with the motor, it is a 2002 motor.

[jb123]

not positive but if your tach settings are wrong you might be getting wrong readings....as ive never seen such a hi rpm....i had a pair of 200's that would hit 6200 with the limiter cut.

[Dennisg]

strange

Hi, you don't say where you are. If you are where it is still cold or where the water temp is cold, that might explain some of it. The colder the water, the faster you will go, to a point. I am not sure of the science involved, but I know it to be fact. But running at 7000, or even 6500 rpm will shouten the life of your motor. I would seriously consider changing the prop so that the max WOT rpm is somewhere between 5500 and 6000 rpm as stated in your owners manuel. You can figure on dropping the rpm between 100 and 150 rpm for each inch of pitch you increase on prop size. Keeping the diameter the same. One of the best places to start with when trying to get the optomin prop size is with the boat manufactuer .
Hope this helps, Dennis