300/440/550 550/750 conversion ?

For those who have completed this kind of deal, how does a 550 with a 750 in it perform compared to a 701 in a Superjet?


Can't compare exactly but I have a conversion ski with a 650 that has coffmans pipe, 44mm carb, reeds, 150psi, 13/18 prop. When I bought my fx1 it had a stock 650 with 130ish psi and stainless prop.

Both skis were about equal, the conversion having a bit more grunt on the low end.


Conversion skis are great fun for the money.

Does anyone know the size of 550 pumps? Just curious
 

dbrutherford

Parts Whore
Location
Fairmont, WV
What kind of carbs are those? What kind of 750 did they come from? That will help you get in the right direction. SXR's used a throttle cable bracket like that. Can you not flip it around 180?
 

kawi440

Nick
Location
Givhans, SC
Last year i did a similar conversion. We built a 750 stroker. I used 650 cases, 750 small pin crank, 750 cylinder, 650 small dome head and a factory 650 b pipe. Yes it was a screamer. (59mph) I used the 440 pump with a 17 pitch prop. I could run with my brothers sxr until we hit chop. It would loose suction and begin the old school porpus. Easy enough to fix though. Use a shovel grate and shim the tail end of the ride plate for a nose down condition to keep the pump loaded. You can get the battery out by turning it sideways on end and pulling it out. I made a water box to fit for this pipe. It is crazy loud but i am considering using an inline silencer. Use a 650 ts stator plate and run 440 electronics to keep it simple. You can do this with a 750 case, but you have to drill the cases for the wiring. By runing the ts stator plate, you can use the 650 flywheel.(lighter) As far as your throttle cable, make a braket to fit your needs. I used an aluminum 440/550 coupler.
 
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