KZ650 - STILL not possible for WOT :-(

Have quickly changed carb intervals as mentioned:
15 pilot, 107.5 main, 4th groove.
 Starts and idles nice.
 But as feared from me big lean (?) spot from 2 to 3k - 1/4 throttle.  Starting to drive only possible with using joke or to roll much more throttle. Above 4k not bad, but too late and dark for further tests.
 For me 17.5 pilots and rich needle was always important to remove that massive lean hole.
 Try tomorrow to set air screw with colortune, but do not think that the air adjustment will help enough.
 Now I am in a dead end

See below picture of carbs. Air correctors well placed? Carb bodies are same type. Internals are good. Slides 1.5 cut as standard.

 

Hm,  i think a VM26 set of carbs (KZ900/1000) are easier to tune and give you more performance to your700 ccm "big block", just my 2 cents. ......

Womtong wrote:

See below picture of carbs. Air correctors well placed? Carb bodies are same type. Internals are good. Slides 1.5 cut as standard.


 

Yes! Air Jets are in correct position ( opposite the air screws ).
Leave the pilot, main jets and air screw alone now.
Your issue is not the pilot mix or main jetting but the off idle mix controlled by the needle and needle jet tube.
Next would be to lift the needle another notch ( although it shouldn't need it )..
Also when you changed internals were the needle jet tubes all the same or did any have more air bleed holes..




 

Maybe I should give this option a chance.
VM26 fits straight or do I need another boots? Internals/jetting is the same like VM24?
 Found them for sale: Are this VM26?
 

 

zed1015 wrote:

Womtong wrote:

See below picture of carbs. Air correctors well placed? Carb bodies are same type. Internals are good. Slides 1.5 cut as standard.



 

Yes! Air Jets are in correct position ( opposite the air screws ).
Leave the pilot, main jets and air screw alone now.
Your issue is not the pilot mix or main jetting but the off idle mix controlled by the needle and needle jet tube.
Next would be to lift the needle another notch ( although it shouldn't need it )..
Also when you changed internals were the needle jet tubes all the same or did any have more air bleed holes..





 

Ok, understand. Will go to last notch and will check the jet tubes for all are same.

What do you think for move to another carb type? 
 

Womtong wrote:

What do you think for move to another carb type? 

 

The vm26's are the same spacing and will just need the matching manifolds with the mounting holes slotted slightly to fit the head.
The vm24 air correctors are suitable for the 26's.


 

VM26 - have pictures posted: Are they correct? Need only to buy KZ900 boots and adapt them? Install air correctors and same jetting?
Think give them a try until pictures are confirmed. Thanks

 Regarding VM24: Just done longet run with 15,107.5 and needle on richest position plus one shim.
Runs great below 7800k. After the same like before: Jerking and maximum RPM are around 8500. Pulls strong and cut under WOT. Carb tubes checked: All the same type. 
See pictures.

 Should I buy Dyna ignition? Have green 3Ohm coils here - maybe should test them?
 Slowly starting to think that this pain is not carb related….

Womtong wrote:

Runs great below 7800k. After the same like before: Jerking and maximum RPM are around 8500. Pulls strong and cut under WOT. Carb tubes checked: All the same type. 




 

So now idle to 7800k is fine ?
No hesitation at 2 - 3 k ?
Just won't pull WOT ?
Do a high speed loaded plug chop at around 7500 - 8000 k to check main jetting is fine and doesn't need a 110..
The 8.5k rpm stutter seems consistent no matter what other changes you have done so maybe there is an issue with the ignition ( built in rev limiter ? ) .
HOWEVER 8.5k rpm is the upper limit for power on a stock engine so it's possible you are running it to the max .
What top speed are you achieving ?
115 mph is around max for the stock 650 so i'd guess around 118/120 with just the 700 overbore on stock carbs and cams.
For the vm26's you need the matching manifolds slightly adapted for the bolt spacing.
Fit the same air correctors and start with the stock vm26 jetting.



 

Yes, everything is fine besides full opened slides. 
 Will perform plug chop at around 7.5 to 8.
 Bike has shorter gearing. But actually at 1.5 miles test road 105mph is maximum. With playing on the throttle (7/8 and wot).

 Will give VM26 a chance.
 Also I will test Dyna ignition.

 Regarding Rev limiter: Installed ignition has nothing regarding this. Only thing is that I use a Daytona Velona speedo with shift flash at 8.500… But this cannot play together in my point of view.

 Crazy, that all changes on carbs only slightly influence the WOT thing. However if I install 102 or 127.5 mains for testing. 

Which sharper cams can directly used in this engine? Maybe I should change them plus new valve springs?


 

Have you tried disconnecting the ignition pulse to your "shift light" ? (it is possible that there is a conflict between the ignition module and the shift light circuit ?)

Womtong wrote:

 Crazy, that all changes on carbs only slightly influence the WOT thing. However if I install 102 or 127.5 mains for testing. 

Which sharper cams can directly used in this engine? Maybe I should change them plus new valve springs?



 

127 mains was miles too big.
107.5 to 110 would be maximum it currently needs.
Going too big only bogs the top end , loses power and increases fuel use.
Which type of camchain does your engine use, early roller or later Hyvo?
If Hyvo then the GPZ750 unitrack cams are the only oem cam that are worth fitting.
They may fit the earlier engine if adaptor cam sprockets can be bought or made but you will lose the cable tacho if fitted.
 

Have old roller chain. I will start with VM26 and hope that this solve the problem.
 Will choke plungers from VM24 fit into VM26?