kawikdogg7

can someone tell me what the difference is between the reg. JS550 and the JS550 SX?

i believe in 1990 they started with the SX. My ski is a 1989 JS 550.
i have the manual for the SX and it look the same when i match things up as far as looks go.

also my ski is stock except for R&D intake grate and a ocean pro ride plate.

i looking to do some light mods on a budget and also keep it relayable.

i am looking for lower to mid range power.

JUST-IN-TIME

pre sx is a piston port no reeds
sx ski has reeds

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jonesy54

i think the SX has a different impeller/pump also.

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-1987 JS550 - bone stock
-1984 JS440 to 550 conversion

JUST-IN-TIME

same pump different shaft and impeller

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jonesy54

ok, i knew the impeller was different, i guess i just assumed the pump was also.

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-1987 JS550 - bone stock
-1984 JS440 to 550 conversion

JUST-IN-TIME

yep ones like 7 splined the other is like 15 splied
u could use any 440/550 shaft just need the right impeller
now if u go with a 440 pump, u get better thrust

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mike84c

'90 sx is not a reed motor, '91 sx is the first reed motor, other info above is correct