Tohatsu 9.9 power gain - carb swap??

SteveRay

Petty Officer 1st Class
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Oct 20, 2004
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338
I have a friend with a mid to late 90's 9.9 Tohatsu outboard and he was told that with a simple carb swap he can increase the HP to 15.

Is this true? Is the upgrade that simple? If so does anyone know the part numbers?:redface:
 

kandil

Chief Petty Officer
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Aug 8, 2008
Messages
567
Re: Tohatsu 9.9 power gain - carb swap??

If it is like the Mercury 9.9 thin the answer would be NO you need more than the carb wait for TG to let you know:)
 

buckeye_sean

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Jun 2, 2004
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Re: Tohatsu 9.9 power gain - carb swap??

Yup, I had a 1992 NS9.9B2 model and with the cam swap went to a 15hp with no changes in the carb/jetting required. (All it basically does is increase the travel on the linkage to make the butterfly on the carb open further.)

Quick, simple, painless & Cheap!
 

SteveRay

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Oct 20, 2004
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Re: Tohatsu 9.9 power gain - carb swap??

Awesome info....Thanks guys
 

SteveRay

Petty Officer 1st Class
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Oct 20, 2004
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338
Re: Tohatsu 9.9 power gain - carb swap??

Serial number:
m9.9b2 56652
 

Sea Rider

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Sep 20, 2008
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12,345
Tohatsu 9.9 & 15 Timming

Tohatsu 9.9 & 15 Timming

Apart from changing old to new advance cam, there are some adjusting timming differences. Don't know how old is your current 9.9 model version, it it were a 9.9 D and wanted to update to a 15 D, both timmings are same, 22? a perfect match; if it were a 9.9 D2 and updating to a 15 D2, there is a 5? timming difference, first has 20?, second has 25?, will need to adjust upper stopper bolt CCW untill tiller & timming mark has advanced + 5? to stop at 25? mark. Tighten stopper bolt nut on that position.

Adjust rod height by means of upper screw, throttle arm rod should be at wot when tiller has reached max acceleration & timming mark has stopped at 25?. There should be no under pressure, just a very slight over pressure of roller against cam, that's why need to adjust if required. The butterfly must be at 180? (wot) when at full tiller end.

This issue may apply or not to your engine, check model and adjust if neded. The same advance + 5? timming applies + carb gasket change when modifying a 25 C-3 to 30 A4.

Happy Boating
 

Platties

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Apr 3, 2009
Messages
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Re: Tohatsu 9.9 & 15 Timming

Re: Tohatsu 9.9 & 15 Timming

Can you tell me if the Tohatsu 9.9 is the lightest 9.9 ever on the market, I was thinking of getting one?

Thanks
 

TGuy

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Mar 17, 2005
Messages
217
Re: Tohatsu 9.9 power gain - carb swap??

Depends which 9.9 you're talking about. The above thread is dealing with the 9.9 2-stroke model (which was the same block as the 15 2-stroke).

The current Tohatsu 4-stroke is actually 9.8hp and yes, it is the lightest on the market.

So if you're looking the new 9.8hp 4-stroke, it's the lightest. If you're looking at an old 9.9hp 2-stroke, I don't know if they were the lighest on the market or not but people bought them because they could turn it into a 15hp with just a simple modification (see above thread)
 

Platties

Cadet
Joined
Apr 3, 2009
Messages
16
Re: Tohatsu 9.9 power gain - carb swap??

Thanks for the reply,

I was thinking about the 2/.

Can you up grade the 6hp 2/ block like you can the 9.9, if so ...what too?
 

Platties

Cadet
Joined
Apr 3, 2009
Messages
16
Re: Tohatsu 9.9 power gain - carb swap??

Depends which 9.9 you're talking about. The above thread is dealing with the 9.9 2-stroke model (which was the same block as the 15 2-stroke).

The current Tohatsu 4-stroke is actually 9.8hp and yes, it is the lightest on the market.

So if you're looking the new 9.8hp 4-stroke, it's the lightest. If you're looking at an old 9.9hp 2-stroke, I don't know if they were the lighest on the market or not but people bought them because they could turn it into a 15hp with just a simple modification (see above thread)

Thanks for the reply,

I was thinking about the 2/.

Can you up grade the 6hp 2/ block like you can the 9.9, if so ...what too?
 

TGuy

Petty Officer 1st Class
Joined
Mar 17, 2005
Messages
217
Re: Tohatsu 9.9 power gain - carb swap??

As far as I know, Tohatsu never made a 6hp 2-stroke. They had a 5hp but it can't be upgraded to any larger size.
 

TGuy

Petty Officer 1st Class
Joined
Mar 17, 2005
Messages
217
Re: Tohatsu 9.9 power gain - carb swap??

So the range went from 5hp to 9.9?

No, they also sold an 8hp. But since the 9.9 was based on the 15hp powerhead, you can't upgrade the 8hp to a 9.9/15.
 
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