300/440/550 JS300/550 Converstion

[richardb]

I bought an 86’ JS300(white ski) in really good shape. I am going to drop in an 87’ 550(red ski). I am planning on keeping the existing 300 pump and prop. My question is do you think I need a bulkhead support for a stock 550? If you have any other advice that would be great this is my first build.

 

[swapmeet]

Have you tried PWCtoday.com? Honestly there are a lot of people over there that have modified this style ski. Maybe someone here will have some advice.

 

[jeremy chambon]

use the 550 pump its bigger than the 300 and u will need the drive shaft also

 

[cookn]

why switch out of the red hull, unless its badly damaged? only the 300 hulls past 1990 i believe are different. The 300 hull you have is the same as the 550 and should fit the pump and drive shaft and wouldn't need bulkhead support, but im not sure about the motor mounts being the same tho.

 

[richardb]

The red hull is damaged. Thats the reason for the switch and I have also read that the 300/440 pump is a better combo with the 550 motor. Motor mounts are the same, it should drop in as I can see.

 

[jeremy chambon]

ive done the swap b4 and im doing another right now for a friend if u want a 300/440 pump thats fine some people say the 440/300 has more top end then the 550 but i havent really seen any prof besides people saying they gps it b4 and after doing the swap and it was only a few mile a hour diff and that can change from a ripple in the water. besides that i havent read any thing about one being better than the othere. what have u heard?

 

[cookn]

I have both a 440 and 550 with similar aftermarket pipes,skat props, and sbn44's. the 440 will outrun the 550 slightly. the 440 pump is said to process water better at high speed, but i find my 550 pump with a stubby pump cone has better lowend snap. Also the 550 prop is mounted to a shaft on bearings in the pump where the 440 prop is mounted onto the end of the drive shaft, which is why bulkhead support may be needed in higher power applications