Need help on 15HP mercury. WOT RPM?

[rafiqi]

Hi guys,<br />I have a 2000 "Mercury Mouse" boat.It has a 15HP<br />2 stroke.My problem is that the the motor will only reach 4800 Rpm WOT using a 9" pitch prop.If I use a 7P it will turn 5200 RPM.This brings it within spec,(5000-6000) BUT I lose top speed by about 4MPH.<br />There are several other boats like mine on the lake and they are all much faster and sound it to!(By the sound they are turning about 6000 Rpm)<br />I have a Tac on mine.<br />Is there a adjustment for max RPM? <br />I have checked my plugs and made sure that the carb butter fly opens all the way.<br />Any idea's?<br />Thanks.<br />Rafiqi.

 

[sschefer]

Re: Need help on 15HP mercury. WOT RPM?

You went from a 9 to a 7 and gained 400 rpm. That's about 100 rpm shy of what you should have gained at sea level. Are you at sea level? Is the motor new or used. If used did the prior owner use it primarily above 2500ft elevation. If so, it could have been re-jetted for high altitude. If not and you are at or above 2500ft elevation you should keep the 7" prop on it and get the carb re-jetted for high altitude.

These are all guesses based on facts that I know to be true sometimes.

 

[hamit59]

Re: Need help on 15HP mercury. WOT RPM?

How many hours is on the motor ? Have you decarbed the motor.Jf carbon builds up in the tuner tube it will not run at high speed. Try running some sea foam through it see if that helps.