76 Evinrude wont increase speed

[benji2682]

I have a 15 HP on a 14' jon boat. Motor runs well, but travel speed does not increase with RPMs. At WOT, boat is not even close to plane. I can feel the prop pushing water and accelerating to a point but acceleration stops. I messed around with the trim and the heighth of the cavitation plate with no success. Motor appears to be fine, the prop hub is fine, and there is no grinding sound coming grom the gears. I am out of ideas, any help is much appreciated. Thanks Ben

 

[chris in va]

Re: 76 Evinrude wont increase speed

I don't pretend to know much about outboards, but it seems to me if the RPM's are increasing with no noticeable speed difference, something's gotta be slipping. When I hit the gas at mid rpm's on my 15, it's very obvious the power is getting transferred to the water.<br /><br />How sure are you the prop hub is intact?

 

[benji2682]

Re: 76 Evinrude wont increase speed

I'm pretty sure the hub is ok. I put it in gear and tried to twist the prop while my brother held the fly wheel and I couldn't make it spin.

 

[fireman57]

Re: 76 Evinrude wont increase speed

Mark it with a permanent marker and take it out and run it WFO. Check and see if the marks are lined up. I believe there is a lot more torque when running than you can put on it by hand.