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15 HP High Thrust?

P

profisher

Advanced Contributor
Hoping someone will know the answer (for sure) to this one before I roll the dice. I have a 2007 9.9 High Thrust (kicker) which now has 4 high hour years on it. Still runs like new doesn't use oil but starting to look ahead to rebuilding it. I don't like the new model 9.9 (stroked 8hp) as it doesn't have the pushing power and the motor mounts are so soft that the engine vibrates around more than it should. My other option involves this; buying a new 15 HP (4 stroke) short shaft, removing the complete powerhead and dropping it onto my 9.9 high thrust leg. Thus creating a 15hp high thrust kicker. I know the 9.9 is a de-tuned 15 so it should work. I was told to check the part numbers from the driveshafts of the new 2012 15 hp long shaft and see if it is the same as the part number for my engines driveshaft. If so it should work unless there is something else we aren't aware of. Anyone know the answer for sure?
 
I'm not trying to alter my present 9.9 block into a 15 hp. My choices are to rebuild the 9.9 when it shows signs of needing it....or buy a "NEW" complete 15hp and just do powerhead (complete) swap so that the 15hp is now bolted onto my 9.9 high thrust leg. I''m not considering any other options. The new powerhead is my first choice as I'm already lugging around the weight of a 15hp, so might as well have all 15 hp. I know that if these were both 2007 engines that this could be done for sure. My main concern is that they have made changes along the way that I'm not aware of that prevents a 2012 model 15hp from bolting onto the 2007 leg.
 
The F15 from 2007 and newer are totally other model engines, they are 362 cc, it is the same as the 20 hp. If you have a 2007 323 cc Yamaha F9.9, you really need to replace it with a F9.9 or F15 323 cc, that is F9.9 1999-2007 and F15 1998-2006. All around the world (except U.S.A. and Canada) we call this model F9.9C and F15A.
 
Yup, went down to the dealer today and found that out. To convince me he showed me the base gaskets from the new 15 and my 9.9, completely different. Did find out that I can still buy a 9.9 powerhead (323cc) at a cost of $1400 CDN for the block and rotating assembly and $1900 for the head. So $3400 and I would still have my old electrics, carb etc. Guess I will be just rebuilding my 9.9 when the time comes. Will start buying the parts now so I have them all rounded up for when I need them.
 
You should keep your money in the bank. I have sold that motor since way back and have yet to see anybody actually wear one out after many thousands of hrs. Other things happen though. Change oil regularly and use Amsoil 15W40 Marine oil.
 
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