Yamaha 20hp Problem???????????????

[Plastic_Magic]

Hi all

My mate has a 3.7 Stessle Edgetracker powered by a 2006 20hp Yammy. A problem has occured. You would be cruising along on the plane and then the motor would just rev out????. once your off the plane then go to get back on the plane it is fine but once you on the plane and hit a bump it does it again. To me it sounds like the gears are only just engaging and when you hit a bump it knocks them out. i also thought the prop bush could be stuffed but only a fairly new motor and the problem with the reving out then working again sort of rules that out. Any help would be much appriciated.

Cheers Plastic_Magic

[FNQCairns]

It's probably getting air under the hull?, he may need to drop the engine mount height a little way.

cheers fnq

[Roughasguts]

Yeah might be ventilating, getting a bit of air around the prop.

But get a black marking pen and draw a line on your prop and along your lock nut and washer. If those lines don't line up next time it does it, then your spinning on your prop bush.

[Lewis...]

could be cavitating because the engine isnt low enough in the water., i no someone who had a very similar problem, try dropping the engine mount down a bit...?

lewis.!

[Spaniard_King]

Plastic,

I recon you are right with the prop bush. has he tried a full WOT run?? Seems the engine reaches a certain level of power and then it lets go. take the prop off and see if the bush is torn. eevn if it appears good. make a mark on the spline and the prop so as after the next run it can be examined to see if it still lines up.

[BaitThrower]

Yep had this happen once or twice. Just be ready to drop the throttle asap if it starts to stop your motor overreving.

As others have said, lower the motor. Anti-ventilation plate should be no higher than the bottom most part of the hull, particularly if you use the boat in a bit of chop :) If this checks out, check prop bush is sound.

[Cobia Kid]

oi lauchie
same problem with me, sounds like the prop is slipping.
to test this put the motor in gear and spin the prop while your mate is holding the
round thing on top, if you can move the prop you will need a knew one or a knew
bush
ill talk to nate tmrw about it,
cheers
P.S. Did you see the whales?:P

[Plastic_Magic]

Cheers fellas

will try these out and let you know if it fixes it.

Cheers Plastic_Magic

[barkers creek]

haha thats my boat lol

wat gets me if it was the bush it would stop all the time i can be driving around for 45min and it wont happen then it will do it ..so i turn the motor off lift it up and drop it back down start it ...and off we go no problmes...relly got me buggerd , thanks for the tips ill give them ago
cheers