Does anyone knows if there is an RPM limiter (governor?) on my 2008 Yamaha f90 LTR.
I recently bought this motor used, and it has only 82 hours on it. My mechanic checked it out and said it appears to be in perfect condition. I guessed at prop size and bought a pontoon style prop made by Michigan wheel -- a 13.5"x13 pitch. I had the motor mounted on my 24-foot pontoon boat, and I went out for the first time with 8 people, all average size adults averaging 180 lb each. To my surprise, my motor quickly got to 6250 RPM at WOT. The recommended range is 5000 to 6000.
I went out a week later with only 2 adults, and I expected it to rev higher, but it did not. It reached the SAME WOT revs at 6250 RPMs. My motor is mounted one notch up on the Transam, and in both outings, the engine was in the exact same trim position, same amount of gas in the tank, same water conditions, etcetera... In both outings, it appeared to reach the same speed and it did not appear to be slipping or ventilating, as far as I could tell.
is there a rev limiter on this motor? If not, any other possibilities that would explain why having considerably less weight (1100 lb),resulted in the same wot RPM?
Obviously, I want to get everything out of my motor that I can. Am I leaving anything on the table with my current prop? Would going to a 15 pitch prop be a wise move? Or am I properly sized now? I have been told that I want to be near the top of my wot range to get the most from my motor, and going from a 13 to a 15 pitch prop on a pontoon boat could have a 500+ rpm decrease. My boat is on a very large body of water and I frequently go long distances of an hour or so at Full Throttle, so I would like to get my prop and engine optimally matched.
Thanks in advance...
I recently bought this motor used, and it has only 82 hours on it. My mechanic checked it out and said it appears to be in perfect condition. I guessed at prop size and bought a pontoon style prop made by Michigan wheel -- a 13.5"x13 pitch. I had the motor mounted on my 24-foot pontoon boat, and I went out for the first time with 8 people, all average size adults averaging 180 lb each. To my surprise, my motor quickly got to 6250 RPM at WOT. The recommended range is 5000 to 6000.
I went out a week later with only 2 adults, and I expected it to rev higher, but it did not. It reached the SAME WOT revs at 6250 RPMs. My motor is mounted one notch up on the Transam, and in both outings, the engine was in the exact same trim position, same amount of gas in the tank, same water conditions, etcetera... In both outings, it appeared to reach the same speed and it did not appear to be slipping or ventilating, as far as I could tell.
is there a rev limiter on this motor? If not, any other possibilities that would explain why having considerably less weight (1100 lb),resulted in the same wot RPM?
Obviously, I want to get everything out of my motor that I can. Am I leaving anything on the table with my current prop? Would going to a 15 pitch prop be a wise move? Or am I properly sized now? I have been told that I want to be near the top of my wot range to get the most from my motor, and going from a 13 to a 15 pitch prop on a pontoon boat could have a 500+ rpm decrease. My boat is on a very large body of water and I frequently go long distances of an hour or so at Full Throttle, so I would like to get my prop and engine optimally matched.
Thanks in advance...
