650/X-2 750 x2 jetting help!

J

jamesbechina

Location
United States
I am in the process of building my 750 x2 and I need a little help with jetting. I got a 750 out of a 1995 ss xi. It has dual keihin 40's I removed the stock flame arrestors and put on aftermarket ocean pro flame arrestors. I also added a coffmans exhaust and drilled the waterbox. Should I bump up a jet size or just open up the high speed needle?
Thanks,
James
 
Last edited:
B

Bob Gruen

Location
Atlanta, Ga
Most needle and seat adjustments on carbs have about 3 turns from closed to full flow. Ideally you'd like to have the carb jetted such that you are properly tuned at about 2 turns, which gives you lee-way in each direction to adjust for atmo conditions. Unless someone can give you more specific advice the best thing to do take it to the water and play with it. Idle shouldn't change much but you will need more fuel on the top end as the motor will be breathing better. If you go out more that 3 turns from closed and you are still lean then you will need to go to a larger jet.

Bob
 
Vumad

Vumad

Super Hero, with a cape!
Location
St. Pete, FL
I put a stock 750 XISS motor into my X2 with a westcoast pipe and otherwise stock exhaust. It was extremely rich. Like barely ran dumping fuel on the ground rich. I sold the carbs so I can't tell you much more. You may not be very rich anymore with the waterbox drilled, but I think you will be. The whole 650 system is very restrictive on the 750 and it seems to run rich.

What I do know is that the stock waterbox and exhaust tubing is very restrictive. Also, if you can get the motor to run well (I went to a 44mm mikuni, B-pipe and Sj waterbox and B1 outlet with all 2" exhaust hose) that the air intakes into the hood are insufficent for a motor that's really pulling some CFM.
 
Last edited:
You must log in or register to reply here.
Top Bottom