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Old 25 September 2010, 16:19   #1
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Country: UK - England
Town: eastbourne
Length: 3m +
Engine: petrol 30HP
Join Date: Sep 2010
Posts: 7
tohatsu 25 to 30 conversion

looking for some advice

i have one of the last tohatsu 25 2stroke engines that i want to convert to a 30hp. i am confused about the process as there is several stories all of which i can believe.

am i correct in thinking that i need to remove the carb restriction gasket plate and just reposition the throttle linkage to achieve more revs.

reason for wanting more power is for my new s.i.b to make it more capable of pulling a knee boarder. i have the factory standard prop 13"pitch 3 blade. would consider to changing to a finer pitch maybe even a 4 blade for the extra grip in teh water?

mainly looking for help on the conversion and what parts i need to do it myself

thanks in advance
tom
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Old 26 September 2010, 16:32   #2
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Country: UK - England
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Boat name: Puffling
Make: Avon Rover 3.4m
Length: 5m +
Engine: Mercury 15hp
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I don't know how to do it, but I know Extreme marine in southampton do them.
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Old 30 September 2010, 03:53   #3
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Country: Australia
Town: Cairns
Boat name: KAHUNAS
Make: Zodiac
Length: under 3m
Engine: 30 Tohatsu
MMSI: wft is a dsc mmsi ?
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Posts: 82
The difference between the 2 motors is the carb gasket, and the timing at WOT.

The gasket on the 25 is slightly smaller. You can either buy the 30 hp replacement gasket, or if the old one is still in good condition, you can cut it. The timing is advanced by 5 degrees.

Attached is the timing, if you need i can also put up a picture of what the new gasket looks like compared to the old.
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Old 25 August 2015, 19:55   #4
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do you happen to know the part number for the gasket on the 30hp?
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Old 26 August 2015, 01:32   #5
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Country: Finland
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Boat name: SR 5.4
Make: Avon
Length: 4m +
Engine: Toh1 3,5 Yam 90/2S
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Think its this one

GASKET, CARBURETOR
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