Question about a Yamaha 25 hp outboard

[Porbeagle]

Hi all
Wondering if anyone can offer any advice on this before I start taking the engine apart.
I have a 25 hp Yamaha 2-stroke on a 3.4 m Avon. The engine has no power when revving up in forward or neutral, but will rev up in neutral. It will run in forward and reverse but once you rev up in gear, it starts to vibrate somewhat and does not have any power.
Propellor is free-turning in neutral.
Petrol line, filter, diaphgram all checked and ok.
Is it any issue with the drive or a bearing etc?
Any ideas welcome.
Porbeagle

[deejaycee_2000]

Originally Posted by Porbeagle

Hi all
Wondering if anyone can offer any advice on this before I start taking the engine apart.
I have a 25 hp Yamaha 2-stroke on a 3.4 m Avon. The engine has no power when revving up in forward or neutral, but will rev up in neutral. It will run in forward and reverse but once you rev up in gear, it starts to vibrate somewhat and does not have any power.
Propellor is free-turning in neutral.
Petrol line, filter, diaphgram all checked and ok.
Is it any issue with the drive or a bearing etc?
Any ideas welcome.
Porbeagle

sounds like you spun the bush on the prop, try another prop and see if it works ....

[prairie tuber]

That would be my first guess as well.

[9D280]

Also can tell by looking - you'll probably see solidified molten rubber where it has oozed out the bush a the joints with the hub & Prop shell. (well, the Ev/ Johns 70's vintage ones do that )

If it runs OK at low / tickover revs in gear and gets progressivley worse then I'd second (third) Prarie Tuber & Deejay's thoughts.

I assume the prop isn't missing half a blade or anthing daft? Might also be woirth checking the blades are all roughly the same shape / curvature etc.....