SX/SXi/SXi Pro 95 750SX Carb issues

D

Dan Rudd

Location
Michigan
After a complete rebuild (including new needles) the carb on our 95 750sx just won't tune. I think the L needle seat may have been damaged during the rebuild which may account for the inability to get it to run properly.

I'm leaning toward scrapping the original carb and replacing it with another.
My question is, should I replace with another CDKII or is there something better for this maching? If I switch, is there much fabricating involved or is it a direct bolt on?

Our ski is mostly stock with the exception of some bolt-on handling pieces (plate, grate, impeller, etc) and a Vortex flame arrester.

Thanks,
Dan
 
kevbo

kevbo

Location
dfw
Any CDKII will fit your manifold and flame arrestor. The only other option is going to Mikuni and that will require changing the manifold and F/A as well. I know Gordy30 on ebay has some new CDK38s that will work without tuning. There may be some new and cheap CDK40s left over from polaris watercraft. Look up Jet-World.com for these. A Keihin CDK42 race carb will also work but are no longer made and hard to find new.
 
D

Dan Rudd

Location
Michigan
Thanks Kevbo,

I've seen a few CDKII carbs online but never knew if there were any differences. So I take it I have a 38?
Would there be big advantages to go to a Mikuni SBN?

Thanks,
Dan
 
kevbo

kevbo

Location
dfw
All single carb 750 came with 40mm throttle plates. If a larger carb is used make sure you also have a low pitched prop to go with it. You can install all of the parts including the jets from one of Gorgy30s (pacific jet sports) new 38s into the body of your stock 40 and basically have a new carb. The Polaris carbs will probably need to be rejetted for single use and the top screw may be capped. Stock 750sx jets are 75-140, the 38 comes with 78-150 which would be an improvement. I dont know what is in the Polaris carb.
 
J

JETSKIER23

Location
LIMERICK PA
dan , get a blue 42 kehin and rock , they are hard to find but it makes my boat a rocketship, i have a 96 sitdown motor in my sx and it blows away a stock sxi and sxr , go blue
 
2

2XLR8

X-
The keihins have a very pointy low speed screw and if overtightened can break in side the metering hole as you unscrew it and that means no fuel for idle circuit.
 
D

Dan Rudd

Location
Michigan
My new blue keihin arrived today. My son called me at work to say the box arrived and is chomping at the bit to get it together and in the water.

2XLR8,
The damage that was done was to the needle. I thnk it was over tightened and the seat was trashed.

Can anyone out there give me a good place to start with needle settings? The motor is stock except fot the Vortex flame arrestor.

Thanks
Dan
 
D

Dan Rudd

Location
Michigan
Hey Kevbo,
I don't entirely follow your instructions to set at "rich of peak". Are you saying to set the low needle to it's peak idle and then just a bit richer?

Thanks,
Dan
 
kevbo

kevbo

Location
dfw
Yes, set idle rpm with the stop then turn the bottom screw to find peak rpm. Open the screw until the engine slows down, often around 1/4 turn, this will be your perfect idle mixture. Same for the top screw except it is tuned at full throttle. You can run at peak rpm as long as the fuel can handle your compression and timing. If you are pushing the limit then tune a little rich of peak power. Usually throttle response will be poor if its too lean. Always go through this procedure when any changes are made because because mixture requirements almost always change as well.
 
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