Off Idle Hesitation

Hello Everyone,

I am having off idle hesitation that I can't solve with changing the pilot circuit or by changing the the needle clip position.

Here's my setup
-4 to 1 exhaust
-air pod
-VM26 ( One set with only fuel screw and another set with fuel and air screws)
-Rebuilt KZ750 motor with a 1984 GPZ head and cams

The off idle stumble happens around 2/3-4k RPMs. I have tried 15, 17.5, and 20 pilot jets with .5 to 2.5 turns out. Note: I haven't yet tried pilot jet 20 more the 1.5 turns out. I tried clip position from 2-4. Best result is position 3. I am currently running air corrector. With the air corrector installed it seems a little worse. Beside the the off idle hesitation the bike pulls hard throughout the entire RPM range and it idles fine. I even bought another set of VM26 from a GS750 with the fuel and air screws and the same result So, I came to a conclusion that I need to install different size cutaways. Currently I have 1.5 installed. I had some spare cutaways laying around so I decided to increase the cutaway with a file. The result improved but not completely resolved. Now the real question what size cutaway do I need? 2.0? or 2.5? And which bikes came with those cutaway sizes? Its the GPZ head and cams are causing this problem due to the increase air flow of the head.

If anyone knows any way to resolve this please chime in. Or do I need to install a different size carbs? Suggestions?

If you live near Chicago I am willing to drive a couple of hours with the bike if you can help me tune it.

What make pods are you using and are the air jets in the correct locations.
To determine if you have a weak or rich condition causing the problem you should feather the choke at the point of hesitation to see what effect that has.
If it worsens you are too rich and if it improves you are weak.
You should also do this with and without the pods installed.
Needle should be left in the middle position.
I can guarantee the air jets are not the issue.

2.0 cut away slide is my recommendation..

Zed,
I know its not the air correctors they work as they should. It’s the cutaway. Because I literally tried every possible combination for the pilot circuit with and without the correctors. Bike idles great.

Racerx311
Thanks for the recommendation I will try finding some

PM sent

The 2.0's were usually used with accelerator pump. (Lean) 1,5 without.
Steve

Have you checked the bowl height?

Gordone,
Yes the bowl height was checked using clear tube method.

Racerx311 is sending me a set of 2.0 slides to try out and I'll update you guys when I dial in the carbs with the 2.0 cutaways.

SWest,
1.0 is the leanest for cutaways then it works its way up to be richer. For VM
Leanest 1.0, 1.5, 2.0, ... Richest

Your last statement about Slide Cutaway is not correct. The 2.0 slide is leaner than the 1.5 slide you are replacing in your carburetors..

You are correct, My bad. I must of read the book wrong. oops.

Here's a update,

I tried the 2.0 slides that racerx311 sent over and it made the condition worse. Then we came to the conclusion that it needs more fuel. So i installed the 1.5 slides again and increase the pilot jet to 20. The pilot jet needs to be less then 1 turn out and air screw needs 1.5 turns out. These settings are for VM26 carbs with pilot and air screws. Now the bike is much better, I don't have to worry about stalling the bike from a red light lol.

I still have another set of 20 pilot jets and 1.5 slides and a Kawasaki version of VM26, no air screws. I might try these.

I still feel like this motor has more to offer.

Racerx311,
I'll try to send out the 2.0 slides today or tomorrow.

The Suzuki carbs with both screws are very sensitive on the fuel mix (the one underneath).
To far out and the motor bogs which feels like starvation .
There's no published settings for these as they were set and sealed at the factory but they don't normally need to be more than around 1/8th to 1/4 turns from seated.
You can actually wind it in lightly on its seat and the carbs will behave like single air screw Kawa carbs.