300/440/550 differences in 550s?

[onesojourner]

here is what i have so far. let me know if i missed anything.

Model differences

1982-1985 Known as JS550
Motor:Black Piston Port 550
Single ring piston
Carb:single 38mm Mikuni BN
Front left side exhaust outlet
Finger throttle
Aluminum pump inlet wear ring (only 82-83)
1986-1990(mid) Known as JS550
Motor:Black Piston Port 550
Single ring piston
Carb:single 44mm Mikuni BN
Front right side exhaust outlet
Thumb throttle
JETPOWER exhaust
Stainless pump inlet wear ring
1990(mid)-1991(mid) Known as 550sx
Motor:Black Piston Port 550
Single ring piston
Carb:single 44mm Mikuni BN
rear exit exhaust outlet
thicker rubber side mats
Maintenence free pump
Thumb throttle
JETPOWER exhaust
Stainless pump inlet wear ring
1991(mid)-1995 Known as 550sx
Motor:Silver Reed Valve 550 (Highly sought after, known for smooth throttle response)
Dual ring piston
Carb:single 38mm keihin
rear exit exhaust outlet
thicker rubber side mats
Maintenence free pump
Thumb throttle
JETPOWER exhaust
Stainless pump inlet wear ring

 

[The other Alex]

Sounds like ya got it.

 

[IceRocket1286]

i thought they all had thumb throttles. no fingers. and i thought they were all left side front exhaust, except the newer ones.

 

[The other Alex]

Some had right side exhaust below the bond rail, I believe that was the piston port sx? The other side exhausts were on the left above the bond rail with the tube pointing towards the water.

 

[oxnard111]

They are all single ring pistons? I rebuilt an 87 a couple of years ago and I thought I remember two rings. I'm probably wrong though

 

[cookerq62]

Do they all have iron cylinders? Or do the reed motors have aluminum with DI sleeves.

 

[onesojourner]

the reeds are aluminum, guess i could add that. the sx all had rear exhuast. you can fit the dual ring in the pp but it came with a single ring.