1979 KZ650B Streamlined Restomod

It might be a Denco. Dose it have markings at the muffler hanger.

No markings as far as I could see, unless its really tiny. The left passager footpeg is mounted over the exhaust mount though, I will remove it and check tomorrow, thank you

I asked in an earlier thread to identify the exhaust, someone said it might be an "alfa/alpha" system, but it does not have the same bend where the muffler meets the header pipes  

kzrider.com/forum/3-carburetor/617023-vm...her-performance-mods

Only 4:1 I can think of that exits lhs is alfa. Laser, piper etc from the day are rhs exit. However these are all UK made pipes, so could be a euro or US pipe that I wouldn't know. 

Guess I'll never know, the exhaust looks and sounds good though, so I'm gonna ride with it untill I can afford a Delkevic 

I've noticed the bike bogs/dies down when I open full throttle. Is the jetting too lean or too rich when this happens? Or should I just play around with the "needle-notch"? It's been a while since the last time I played around with carb-jetting on bikes, so go easy on me 

Edit: the throttle response is close to perfect untill 3/4-full

With my limited experience, I'd guess that your main jet is too large. Do you recall what size you have installed?

15 pilots and 110 mains.

I have 17,5 pilots and 107,5 mains laying around. Guess I'll try 15 pilot with 107,5 mains. At least it's an easy job to switch with the henry abe filter 

I run 15 pilots and 107.5 mains vm24's on one of my 650's with unfiltered velocity stacks and a straight pipe 4 into 1. 11/2 turns out airscrew, needles slot 4 from top standard needle gives a perfect plug colour and no flat spots.
However it does have high comp pistons, high lift cams and lightly skimmed head giving about about 220psi comp. (black 650 below) 

Main jets 107,5
Pilots 15
Needles slot 4 from top.

Feels like the bike can tolerate a little more throttle without dying now, but hard to say for sure

Tried everything from 1/2 - 2 1/2 turns out on the air screws, didn't make alot of difference.

Bike revvs good untill about 2/3 of full throttle then it bogs down. Idles just fine

Wondering if I might have an air leak somewhere.. any pointers? I disassembled both the airfilter and carbs + the 4*boots for both and installed them as tight as possible without ripping them, anything else I should do, any pointers? 

switched out the spark plugs to new BP7ES, the old plugs were sooted really black.


Last resort is going back to the stock airbox, but I reeeally dont want to   

New plugs after driving around a little bit, this is after playing with the air-screw, so I dont know if it says anything

Plug looks a little better...I'm gonna say try moving up one slot on the needles. Maybe it's just getting the full amount of fuel too quickly. If not that I would try 102.5 mains, but I'm hesitant to make any suggestions that cost money.

You may be able to test my richness hypothesis by taking the air filter off and seeing how it likes that at higher throttle positions - it probably won't be happy at idle.
 

Don't chop and change more than one thing at a time. You'll loose track and not know what has caused what. 
Intake affects mixture far more than exhaust so start with 15 pilots/102.5 mains/needle slot 4/airscrew 1.5 out. 
I don't know anything about the air filter you are running or if it has a foam or paper or oiled or dry element. 
Once your set up as above colour tune at 1800 rpm. You want to see blue with the merest tint of orange on all four. 
Then balance the carbs. 
Then go for a run using higher revs. After a few minutes running 6k or above then immediately kill the engine and coast to a stop. Take a picture of the plugs colours and post them here. The plug colour will tell you wants happening at high revs. 
 

Thanks for the advices

I have 102,5 mains laying around, as that is what was in the carbs pre-restoring it.

The filterbox has an oiled foam-element inside.

Before installing the filter (the first time) I read a tip about taping off everything exept 6" on the bottom of the filter, to avoid rain and side wind. But since it has an oiled foam element inside, and I'll mostly ride during sunny days , i removed 6" of tape at the top aswell, so now only the sides are taped off. (aiiiiir) - like this

After removing this it feels like the bike is behaving much better, it still bogs down at 1/2 - 2/3 gas untill full throttle (I put some marks on the throttle to see it more accurately), but not to the same degree, now its more like stuttering instead of "choking"

I'll try your method Warren3200gt ​​​​​​, thanks for a great write-up!

I might however try to drop the needle a notch down/putting the clip one notch higher before switching the jet again, what do you think?

~ 107,5 mains and 3'rd notch on the needle
Or
~ 102,5 mains and 4'th notch on the needle