MR-1 RPM

[ncnmra]

Perhaps the throttles were out of adjustment (or still are) and therefore would not make it up to 10k on the one engine until just recently when they were adjusted (or they fell out of adjustment shortly after delivery and still are out of adjustment)?

I thought of that too, but I'm not sure what else there is to adjust on the throttles. I can see the butterfly valves rotating, and there is a stop at the bottom of the throttle that the cable is attached to that is being hit. If I have the throttle lever in the fully forward position, there is no play or slack in the line, the throttle lever actually makes the butterfly valves hit the stops.

I intend to do a compression test for both engines and also to run YDS in logging mode for both engines to watch what happens with both sets of numbers to see if there are any discrepancies. At this point, I know the boat is running well save for a less than 2% difference in the two engines. I sort of think it is all within spec, and its just the nature of the beast, but I want to rule out any symptoms. I will check out the pump bearing(s) at the end of the season.

Barring anything more serious, I think it is a factor of slightly higher elevation, as well as the roles that the varying impeller pitch plays overall.

I think 50mph with a loaded boat is within spec.

 

[Beachbummer]

Hey there, Any updates on this one? I'm hunting a similar issue and could use some pointers.

 

[ncnmra]

No real update, other than I sort of relegated I was chasing a bit of a ghost. I did compression tests on both engines and all the values were great. I can get both engines up to 10k rpm on flat water, but the port takes slightly longer. I am pretty sure that Speedling is correct that I could use a slight repitch, but I'm not going to bother.

 

[Beachbummer]

Thanks. Sounds like you got it figured out!