Power loss at higher RPMs

[BarkingDog]

I have a 2003 Honda 5HP (4 stroke) on my dinghy. This weekend it started losing power at higher RPMs. Sounds just like a spun hub, however this engine has a shear pin and it is totally fine. Seems like the transmission is slipping. Is this possible? There is no thug, clank or any sound other than the engine just reving higher with no additional power. I can put around at 1/3 throttle all day without issues. As soon as I give it more gas, the engine just revs higher and it could be completely disengaged. I didn't run it for long in the slipping state in fear of causing more damage.

 

[Flakeys]

Re: Power loss at higher RPMs

Just to confirm its not a spun prop, with the engine off, shift it into fwd gear and try to rotate the prop by hand. You never know.....

 

[BarkingDog]

Re: Power loss at higher RPMs

Thanks for the reply. I thought that no one was going to help..

What should happen when I try to spin by hand with engine off and in forward gear? If the prop is spun, then the engine should not crank and the prop will spin and if pop isn't spun, then the engine will crank when I force spin the prop, right?

When I say crank, I mean like when you pop the clutch with a car going down hill in forward with the key off (key on would start). You can hear the engine crank.. I can't think of a better word.

 

[Leeshor]

Re: Power loss at higher RPMs

Sounds like the input shaft gears are failing to engage the pinion gears in the lower unit. Try adjusting the gear shift linkege to make sure the gears are fully engaged. Typically a pair of locking nuts on a threaded rod which connects the gear shift lever to the lower unit.