convert 15hp yam to 20hp?

[htdawg]

Hi,
I have a 1999 F15hp 4 stroke yamaha outboard and from what I have seen for the 20 hp model is that they have the same engine size (362cc) what would I have to change on it (if possible) to turn it into a 20hp is it just a matter of installing a larger carb?. also does anyone have a pic of what the alternator looks like cause I would like to hook it up to be able to charge the boat's battery & run lights ect.. also is it easy to do this?


Thanks
Htdawg

 

[WillyBWright]

Re: convert 15hp yam to 20hp?

In general, the 9.9 and 15 use the same block. I don't see that a 20 4-stroke was offered in 1999.

Some F15s have a lighting coil under the flywheel already. You tap into that (or add one) and attach a rectifier that you also wire to a battery. Such kits are offered and available through any Yamaha dealer. Not much involved, especially if the lighting coil is already there.

 

[htdawg]

Re: convert 15hp yam to 20hp?

Hi,

Thanks for the answers! I saw that the new 2007 models were the same size and thought that maybe for my model it might be the same and that I might be able to increase the power abit. Otherwize I guess I will wait till I save up for a bigger one. btw I live in Greece and yamaha outboards are a little expensive I think for a new 20 to 25 hp they are over 3000 euros, for a used 15hp I have seen around 1800-2000 euros.

Thanks again for the answers!!

Htdawg

 

[Ruggybuggy]

Re: convert 15hp yam to 20hp?

I have a Tohatsu/Nissan 20 hp (2008) and it has the same powerhead as my 15 hp Yamaha. The Yamaha is an '01. Should be fairly easy to turn it into a 20.

 

[Ruggybuggy]

Re: convert 15hp yam to 20hp?

So I did a little research and if you can find a intake manifold and carb from a 20hp Nissan/Tohatsu 4 stroke them you should be able to turn the 15 Yamaha into a 20. I check on the carb and it was around $160 new.