I have a 25hp tohatsu outboard 2 stroke engine at low speeds all ok but when i give it full throttle it revs ?

Question

high and decreases in speed i then have to decrease speed and then seems to re engage and be fine for another 5 Min's is this a slipping clutch many thanks

Answer 1

There's no clutch mechanism like in some transmissions. Assuming that your engine was running normally before, it appears as if you have "spun" the hub in your prop.  This is a rubber filler between the prop shaft and the prop itself.   On small motors like yours most people just replace the prop.  There are other problems that can cause this but there would be a "clunking" as the engine "jumps" out of gear. I hope this helps!  

Answer 2

The spun prop question is the logical choice. Sometimes the prop will move over the hub and mark up the face of the lower unit.

     The only exception I ever saw was on a chrysler which had a 2 piece pinion gear which was soldered together with silver at the factory. Must have been a friday because they couldn't wait around long enough to put all the solder in the piece.(Oh ya didn't take us any time to figure that one out!)

Answer 3

Richard got it right! The proof you need is to put 2 punch marks on the prop; one on inside next to prop shaft, the other in-line with the first mark;on out side of rubber hub. Take boat out till prop slips again, and you should see that the two marks are not in line anymore. Prof that hub is spun! Or just take it to a prop shop,easiest of all!!