SX/SXi/SXi Pro Carb & pipe tuning problems.

[Rossar]

Hi!

I'm fairly new in jetski world, so I have some basic questions for you that know better.
I recently bought Kawasaki 750sx ( about 1995-1996) with following mods to the motor:
Dual 40mm keihins, stock flame arrestors without those rubber pipes, R&D exhaust manifold,
Factory pipe, timing advance plate, some aftermarket ignition system, slightly lightened flywheel, lowered head.

There is fairly new pistons in, like 20 hours been there. Compression test says 150psi.

I have been struggling with carb settings for a while now so I would like to get your opinion on these.

Main jet: 150 adjusting screw 1/2 turn out
Pilot jet: 88 adjusting screw 7/8 turn out
Pop-off: 25 psi

I haven't yet changed the jets my self, these are the jets that previous owner had in.
I've only adjusted the screws and lowered the pop-off , from 35psi.
Does anyone see a problem on these?

The low end power is totally missing, on the high end it works decently.
But because of my driving is mostly freestyle, the low end really needs some improvement.
I have a feeling that on low rpms the jet runs really rich, and then it takes some time to get it running again.
Like after when I ride on low rpms for a moment, I have to drive on full throttle for 15s before it gains the full power.

Also I have a problem that the pipe is running really cold.
I replaced all the adjusting screws on the pipe, because they were stuck.
Now my screws have a flat end. Does the original have a sharp end?
I'm just thinking that when I open the bottom screw 1/2 turn, the whole hole is totally open.
Now I'm running top and middle screw closed, and bottom 1/4 turn open... And the pipe is still cold.
Should I just close the bottom more than 1/4?
Factory pipe just recommends that not to close all 3 screws, I'm pretty close to that.

Hopefully you can help me with these.. Thanks!

 

[heynagel]

All those aftermarket parts and no high compression head? That's kinda strange. I do know the factory screws have a taper to the to fit in the hole better.

 

[Rossar]

All those aftermarket parts and no high compression head? That's kinda strange. I do know the factory screws have a taper to the to fit in the hole better.

Ok, so then it is propably ok that I close the srews abit more than Factory suggests.

You think that this setup would benefit from high compression head?
Witch one do you preffer? 180psi is something to aim for?

 

[heynagel]

this is what a factory pipe screw looks like, the tapered smooth end fits in the inner jacket of the headpipe to seal off water. So I'm betting a normal screw in there would not seal very well if at all. As far as compression 180 is a safe psi to run in a motor to get hp while still being able to use pump gas

 

[Magyar68]

Which of the Factory Pipes do you have? If it is the Limited pipe the Low jets are to high, and the High Jets are to High for Keihin CDK II Carbs. 75, and 120 Are on my 93.

 

[Rossar]

It's not the limited pipe. Its the older version. (don't remember the name of that)
I did go down on low jets from 88 to 75, and it runs alot better.
Also the pipe is now running at decent temperature, thanks for tips on that!

Previous owner had put the cooling lines in that way that waterbox filled with water.
Now I have a restriction on the line and the waterbox works perfectly.

Now I have only one problem left.
When I run on 1/4 throttle and then hit the gas, it does have a lag before it rips.
This is very annoying when approaching a wave planning to jump, it does not give the power exactly on the right time.
If I pump the throttle first once, then it hits immediately when I open the throttle again.


I have tried to adjust the low and high screws but they don't seem to help.

Could this problem come from wrong pop-off pressure?
I'm now at 25psi.

 

[Rossar]

Just ordered R&D single intake and Pro-tec tapper bored 46mm Mikuni SBN.

Any idea where should I start on the jetting? 120/150?