Z1r issue starting

78 z1r.....at first I was using a set of 26mm ran fine
Then I got a set of original 28mm but was running rich with 125 mains and 25 pilots
This is when the problem started...I then change the pilot to 20 and was missing between 3500 and 6500rpm.
Park it and order a set of 22.5 pilots with same result.
So back in with the 25 pilots and know it spites out the carbs and with the choke it will spite and back fire.
Since then I have tried 3 sets of carbs two Dyna S and two sets of coils
Check timing...valve gap and compression
All check out....
I have never ran into this issue before and have ran out of ideas and reading the Kawasaki Manual.
What an it be? Is the question

Valve clearances?
Steve

Check.....
Also have good spark on all four.

It wasn't broke until you fixed it... :pinch:
Been there.

What position are the needles in? The problem starts at 3500 rpms. The carbs should be coming on the mains at that point. Try lowering the needles (raising the clips), If the clip is already at the top, go to a smaller main.
However, you said you've tried 3 different sets of carbs, 2 Ignitions and 2 sets of coils. If the symptoms remain the same with all those changes, it's got to be something that hasn't changed. When you checked timing, was that spark timing? Spitting back thru the carbs could indicate cam timing is off.

Yes check spark timing with a pencil light according to Dyna S instructions and also the timing chain.
I'll check all those again tonight again.
But you are right...back firing normally tells timing is off.

Or lean. Air leaks?
Steve

I would start with fouled plugs 25 pilots way to large is it the 78 style Z1r carbs or the 80 version ?

Alright guys found the problem.
At first I had found that the magnetic rotor was dragging against the advance assembly . I'm guessing that was causing my breakup above 3000rpm.
When I notice this I remove the rotor and file it down a bit till it cleared and move freely.
This is were I messed up. When I install the magnet rotor back on ..it when on at 180 degree.

I had to buy a new rotor. The 2 year old one was worn out. Suggest you grease it well. Only aluminum.
Steve

20 pilots are way to big. It should run fine on 17.5 pilots. Are the 28's clean? Check the jetting from the 26's then use that as a base for the 28's.

Yes original 28mm carbs
Ended up with 125 main 22.5 pilots
2 turns out on air screw
Pods and 4-1 kerker with 2.5 race baffle
Perfect idle and no problem revving