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Old 14 September 2007, 06:08   #1
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Country: Ireland
Town: Cork
Make: Avon Searider
Length: 5m +
Engine: 60 HP Yamaha
Join Date: Mar 2005
Posts: 6
Question about a Yamaha 25 hp outboard

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
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Old 17 September 2007, 05:01   #2
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Country: South Africa
Boat name: Fukumoto 8
Make: Ceasar
Length: 4m +
Engine: P750 tohatsu
Join Date: Aug 2007
Posts: 6
Quote:
Originally Posted by Porbeagle View Post
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 ....
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Old 18 September 2007, 08:29   #3
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Country: Canada
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Make: Gemini
Length: 4m +
Engine: 40hp 2 str
Join Date: Oct 2003
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That would be my first guess as well.
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Old 19 September 2007, 09:11   #4
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Country: UK - Scotland
Boat name: Wildheart
Make: Humber/Delta Seasafe
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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.....
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