89 X2 with a 750 small pin, Sudco blue 42mm Help?

[lovewinz]

I have a 89 X2 with a 750 small pin, Dual Sudco blue 42mm (, Low screw 1 1/8, high screw 1 1/2), factory pipe (2 screw version) SX chamber, Westcoast water box, ADA head 26cc domes (180psi +/-2), Boysen reeds, MSD Enhancer 4251, Taylor Cable 8mm Spiro-Pro wires, Jet Dynamics intake grate, Jet Dynamics 2" set-back pump, Mariner reactor swirl prop (pitch unknown), Ocean Pro ocean D nozzle,

Now the problem, I cant seem to get these carbs tuned right.

Took it out yesterday and set the idel to 1300 but when I hit the throttle for a pratice start it died. I adjusted the low screw to the point where the idel came up to about 1500 and hit the throttle and it plowed the water for 10seconds and then jumped out of the water like a rocket. I then found that it I helped if i held the throttle at 18000-2000 rpm and hit it it would take off on a start like it should. When riding on the water it was fine could launch over waves fine throttle response was good. Just not sure why it would plow then take off.

I keep being told those blue carbs are garbage and just to get rid of them.

 

[fastgtfairlane]

Sounds like you need to either change your low speed jetting and or adjust your popoff or possibly you have a dirty carb. Either way I'd take it off and take it apart to see what you're working with and go from there.

The keihins are good carbs, the downside is finding parts and jets to tune them. Mikuni sbn parts are very easy to find so that's a big reason why people don't use keihin carbs.

 

[WFO Speedracer]

Sounds like a lean bog, first off how many turns out is the low speed screw ?

You cannot adjust for highest idle , that will almost always be too lean, you need to set the low speed where uit is slightly over rich then adjust the idle back up with the idle screw , if you have to go more than two turns out on the low speed screw you need a bigger low speed jet.i

 

[lovewinz]

180psi +/-2, Low screw 1 1/8, high 1 1/2, I ordered a pop off gauge to check that and plan on getting a rebuild kit.

 

[Vumad]

180psi +/-2, Low screw 1 1/8, high 1 1/2, I ordered a pop off gauge to check that and plan on getting a rebuild kit.

Buy genuine carb parts. I bought SBT rebuild kits and couldn't get them to seal. I put the old parts back in and got the tests correct. I then bought genuine mikuni kits and had great results. I also had more issues with leaking needles with generics that I didn't have with genuine mikuni parts. I was not happy with WSM or SBT carb parts. Not sure the case with keihen parts. I can probably get you some specs on a 44mm mikuni. Never tuned a keihen.

Prop is not likely the issue but can be. My ski struggled at low RPM but it was over propped. It wasn't a lean / rich reaction, sounded clean, just wouldn't pull until it got onto pipe. No one else with my setup has the prop I do so I'm sure that's the issue.

 

[kevbo]

Your bottom adjusters are for idle only and you have them too lean. If it responds well from 1/4 throttle then the pilots are okay. Make sure the top screws are opened so that the RPM ends up a little below max or just wherever the ski accelerates the hardest. The impeller could be causing much of the problem if it overloads the engine, this was extremely common. Those keihins are very good carbs, anyone that cant make them run has no credibility.

 

[lovewinz]

I ordered rebuild kits from Sudco. If I open the the bottom any more than it is the ski just dies.

 

[lovewinz]

I got my rebuild kits in. The pop off was blowing at 25psi. They started blowing bubbles at 20. I put the kits in and set pop off to 15-16psi. High speed jet is 115, Low speed jet is 90, needle seat is 1.5. Will water test for Fathers day weekend.

 

[JC-SuperJet]

Should pop clean. No bubbling or fizzing. Means the Needle Valve is leaking. Maybe it's the Valve Body O-Ring. Or maybe its the Needle Tip with a wear groove.

 

[kevbo]

A 90 pilot is probably too big for a dual carb arrangement. And a 115 main is on the small side. Try it but make sure you can open the top adjusters enough to reduce power at full throttle.