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Old 02 July 2012, 22:33   #1
Country: USA
Town: Jacksonville, Florida
Boat name: Blue Bomber
Make: Bombard
Length: 3m +
Engine: Outboard Nissan 8hp
Join Date: Jun 2012
Posts: 47
Nissan NS8 8hp conversion to 9.8hp

I have heard that this can be done. Anyone have any advice or experience doing this? Is it just a carb swap?

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Old 04 July 2012, 01:40   #2
m chappelow's Avatar
Country: UK - England
Town: yorkshire
Boat name: little vicky
Make: avon ex RNLI
Length: 3m +
Engine: tohatsu
Join Date: Mar 2008
Posts: 2,310
Thinking if doing my Twatsoo 8 to a 9.8 at some time
Looking at and Comparing the parts list looks like its just replacing both jets in the carb.
did it with a points ignition yamaha 15 to a 20 many years ago that was just a jet swap and a new or hole making in the gasket tween the engine and carb.

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Old 04 July 2012, 02:02   #3
Country: UK - England
Town: East Anglia
Boat name: Nimrod II
Make: Aerotec 380
Length: 3m +
Engine: Yamaha 15Hp 2-stroke
Join Date: Nov 2007
Posts: 5,117
Often there is far more to make these "easy" hp upgrades to the next model than folks think.

On the 9.8 Tohatsu vs the 8 the following part numbers are different...

Cylinder head
Head gasket
Exhaust gasket
Carb body (this could be as a body is supplied with the different jets already in though)
Carb jets
Coil plate stop

I know the revs need to be set up by 500rpm and I'd be amazed if there wasn't a different timing setting. There are also some differences to the engine breather hoses and orifices.
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