X2 - 750 conversion ski jetting ideas?

Zero Client

Zero Client

BeerrroooOOOT!!!
Location
Douglasville, GA
Hey guys,

I'm working on tuning this X2-750 small pin conversion ski. Currently the only bolt-on mods are flame arresters (No pre-filters) and a JSU high-compression head. I'm currently using only the stock X2 prop which I know is going to be out-powered soon.

I just want to get a little closer with the stock 40mm Keihin carbs without spending a bunch on new carbs. It was suggested by a local guru to turn the highs out 1 extra full turn to start (2 full turns out really) with no further modification. Pop-off pressure is 27~30psi in each.

These carbs each have 3 jets (Whereas Mikunis I've seen usually only have 2).

Any thoughts at getting anything closer or do you think I'm good atm?
 
Vumad

Vumad

Super Hero, with a cape!
Location
St. Pete, FL
If the carbs are stock to the motor, I believe they are 38mm carbs. The 40mm carbs only came on the SXR. Don't hold me to that, but make sure you know what you have.
 
Zero Client

Zero Client

BeerrroooOOOT!!!
Location
Douglasville, GA
You're probably right. This quote from Group K explains a lot... err... nothing?? Keihin must be using the guestimate scale by my guess because tis even hard to make sense of this:

in the SLEEPER kits, the stock 40mm Keihin carb (it's actually 37.2mm) is bored to a true 40mm. (Note: The 38 mm carbs on the big pin motors are actually 33mm. We make them a true 38.) This throat boring is an extremely cost effective way to increase intake ability without compromising easy starting, smooth idling, easy adjustment or fuel consumption. For customers who want to install a larger single carb, the 42 Keihin carb, used on most single carb Group K Hammer 92 kits, offers better overall fuel mixing and throttle response than any large throat single carb we have tested. This 42mm carb bolts directly onto the stock 750 intake manifold and provides throttle response and acceleration that few dual carb setups will match. The single 42mm Keihin carb has no troublesome linkage, and it features easy "two screw" mixture tuning. Your stock flame arrestor matches perfectly to the opening of the 42, however the intake manifold must be bored slightly to accommodate the larger 42mm carb throat diameter. NOTE : Boyesen reed stuffers are recommended for all pre 1995 Group K 750 Kawasaki engine kits.
Click to expand...

This is kinda reading like small-pin motors have 38/40mm carbs, and the big pins have 33/38mm carbs. I'm completely confused!
 
Magyar68

Magyar68

Really!!!
Location
Lewisville
Stock exhaust 75 Lows, and 115 Highs, Ignore the #45 return jet. Jetting can be hard to find for Keihin if you plan on going any further performance wise going with Duel Mikuni's is not a bad idea. For a mostly stock boat that jetting should work fine. Don't spend too much time fiddling around with the adjusters, those carbs came off of a (most Likely) some 750 with much larger exhaust, and It will not be as easy as using the adjusters.
 
Zero Client

Zero Client

BeerrroooOOOT!!!
Location
Douglasville, GA
You are about the third person saying I may be too rich. Now I have a factory blaster mod pipe. I was able to get some jets online, went with 82 lows and 140 highs.

Do you think I need to drop back to 120 highs?

Thank you.
 
Magyar68

Magyar68

Really!!!
Location
Lewisville
Oh this is also posted on the other site... I think you should start with he Factory Pipe specification 75 Lows 125 Highs, 25 PSI pop-off for AM flame arresters. I Tired 130's on mine as well as 120's and the result was not surprising the 130 produced your exact issue, the 120s it would just die when you grabbed hand full of throttle.
 
M

Mac Clisso

Location
Hastings, Mi
Magyar68 said:
Oh this is also posted on the other site... I think you should start with he Factory Pipe specification 75 Lows 125 Highs, 25 PSI pop-off for AM flame arresters. I Tired 130's on mine as well as 120's and the result was not surprising the 130 produced your exact issue, the 120s it would just die when you grabbed hand full of throttle.
Click to expand...
I'm looking for jets for my keihin 38mm what are the jet part numbers you got? I got n242-35 which works in both holes but the n242-36 it too big and is what should be my main jet and I can't find anything that will work it's very frustrating!
 
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