300/440/550 Help me choose which carb for my JS550

[Dan Rudd]

I had posted this in the 550 section without any replies. We were hoping to order our SBN right away and were hoping to have a better understanding of what we need before we order it.

We're looking at adding a Mikuni SBN to our 89 JS550 which currently has the BN. We just can't get that BN to tune no matter how much we tinker with it and we want some more reliability.

The motor has a fresh complete rebuild. The ski has the following mods.
Ocean Pro head
Ocean Pro intake
Ocean Pro Vortex
Coffman half pipe
DG waterbox
All the handling goodies, impeller, grate, ride plate, etc etc

When looking at carbs on-line we find a couple that have their specs listed. Being new to this carb I don't have a clue where to start. If someone knows their way around this carb please give me your 2 cents on which one I should consider.

Carb#1
120 Low
140 High
2.5 Needle
80 gram spring

Carb#2
100 Low
125 High
2.5 Needle
65 gram spring

Thanks,
Dan

 

[d_moss]

Probably just going to have to get one and try it. The 44s come on single carb super jets so they are easy to find. And jet it accordingly. One off a 650 sj might run fantastic with just screw adjustments. Buy jets if needed at the local rec vehicle place.