Keihin Cr´s breaks-up at full throttle

One month jetting my Cr29 on my Kz650 and can´t solve that. Bike pulls clean and hard but starts to break-up the mix at 4th gear full throttle (100 mph) and on 5th don´t pulls to more speed. I´ve to roll off the throttle because the bike deads. Now 115 Mj,240 Main air jet, 80 Sj and YY8 needles at 2nd clip. K&N individual filters and Harris exhaust with competition baffle, Dyna-s with green coils. Now trying with 110 Mj but first impresions aren´t encouraging to solve it.
How about 250 Main air jet trying to lean the mix or smaller Mj like 105 or less?
Greetings to everyone

Entering at Jarama track (Madrid):

Since the engine pulls freely in all gears at all revs until the bike’s speed hits around 100 mph regardless of whether it’s in 4th or 5th gear, it seems that the bike cannot overcome the 100 mph wind resistance. If that is the case, it appears the modifications you have made reduced the engine’s top end horsepower. A stock KZ650 will easily pull beyond 115 mph. Did it have this problem with the stock carbs and airbox? Ed

Yes, with stock Vm24 and airbox pull beyond 115 mph. Now the bike pulls harder but the mixture breaks for some reason (i think leaness)but changes at main: 125, 120, 115, 110 shows little differences and cannot pull beyond 100 mph. I would add at least 25 mph more without the problem in 5th

As you have come down in main jet sizes have you noticed any change? Did it get better or worse? Have you tried (I know at 100 mph it could be problematic) setting the choke to part on and see if the issue gets better or worse. If it gets worse then you are too rich, if it gets better you are too lean.

Might also think about fuel delivery to the carbs. At wide open throttle can enough fuel be provided by the petcock and bowls to keep up with demand.

If your motor's stock (?) you might be
better off with some VM26's or maybe VM28's.
I know making my VM29's work on my 750 motor has been fun.

Going down on main jet sizes seems to improve a little. Bike pulls harder but still I have the problem on 5th. Top end speed with 115 Mj: 100 mph. With 120 mj: 90 mph.
I´ll try to setting the choque when bike dies.
Maybe petcock could not provide enough fuel at 5th full throttle for this carbs?

just from my experience with CR's....

Dyna - S ignition? often found that many carburation problems with CR's were actually ignition related, specially at high RPM's, and very very very often with Dyna S.....

over at sohc4 its full of people who simply stopped using them,

Yes Turboguzzi Dyna-s, but what may be the incompatibility between carburetor and ignition only at 5th?
Someone in this forum with Cr´s and Dyna-S?

as you can fully imagine, the ignition doesnt "know" you are in 4th or 5th

but at those gears (4-5) the engine is pulling against a high load at full open throttle, so any ignition malfunctions are more evident. in lower gear you are not against such high loads and you dont hold the throttle fully open for more than a few seconds untill you shift up, its a transitional situation.

as you can see from my avatar i road race vintage bikes and i simply have seen so many cases where the dyna-S was causing the problems, just life experience :)and just not a very good system, IMHO of course.

the fact that changing jets doesnt solve it is also another hint to ign. problems.

BTW in all my race bikes i use re-cycled GSXR ignition modules and coils and all my bikes have CR's.

you can try another little trick: are you using R type plugs (resistor) and resistor caps? if not, try using them. its a cheap try that could work.

of course, nothing i say is written in stone, i've been proved wrong before

"you can try another little trick: are you using R type plugs (resistor) and resistor caps? if not, try using them. its a cheap try that could work."

Is this to drop RFI that may be interfering with the Dyna S? Using both together would drop the spark energy a lot. It would be more prone to have high RPM Missfire with a weaker spark.

What is measured voltage actually being received at each ignition coil primary terminal?

And how does such voltage at the coil compare with voltage measured across the battery posts?

Good Fortune!

I installed solid copper core wires (non supression)and non resistor caps because is what recommends Dyna and Rob from Z1Enterprises with Dyna-S. I supposed Dyna-s isn´t affected by RFI because it´s not an electronic sensitive equipment. Anyway like said Turboguzzi it´s a cheap try.
Testing the bike at 100 mph on 4th main fuse blows and after this blows occasionally. May have relationship