77 KZ650 carb synch ?

So, I had carbs off and did the wire mechanical synch. Have the bike warm and running at idle the vac is 12 hg/cm in 1 and 2 and 3, 4 is higher 20 hg/cm. FSM says 19~24 HG/CM. When I started turning adjusters it started to run very rough. Quite a few turns from the bench wire synch setting. It was running pretty good at that bench synch level. My question is do I set em all to 20 and give her a run or just balance em all at the same pressure? The gauges I have are pretty cheap, but they seem calibrated to zero. Any help appreciated, fresh eyes tomorrow. R

Getting all four the same is more important than the number. If 1 & 2 are the same, an 3& 4 are the same, you are nearly done. Just use the middle adjuster to get the two pairs to the same reading.
If the gauges are not equally calibrated, or if they are terribly cheap, you may be chasing your tail.

I don't think there's a middle adjuster on VM24 carbs, assuming that's what he has.

#3 is usually the lead carb. No adjuster. Valves have to be adjusted, timing right, no air leaks or you won't get it right.
Steve

Thanks. Valve clr, timing and leaks controlled. No adjuster. Balanced or to FSM hg/cm? I am thinking to try FSM vacuum on all 4. Will see. R

Set your idle as low as it can be and still run. Set your bleed screws at best idle. Don't be worried about the HG/CM reading, just that all four are the same by 2%. You might have to readjust the idle a few times. A fan will help with this. Take your time. Shut it down and let cool if you need to and try again.
Steve

On the VM24SS carbs each carb has an adjuster. There is no lead or master carb. Ed

That's good to know. So when bench syncing them, one carb should be set and left alone so the others can be set to match on the bike.
Steve

Ok with fresh eyes. All balanced at a reading of 10 hg/cm. Running and idling smoothly. There was no way to establish FSM vacuum levels onthe guages i have. I would reach the end of adjustment range on two carbs and still have poor running condition. One of the adjuster tangs broke its slot tab but I got the fragment out and it was at final setting. Will replace next time carbs are out. I crossed all the gauges and they are calibrated well same reading at each gauge from each carb before adjustment and after. BTW a extra long JIS is in my future. The middle carb top screws are a PITA. Used a hex bit and socket driver for final tightening. I think she is as good as it can get for a 38 yo kz650 w 25800 miles. It's a keeper. R

I replaced my screws with SS Allen head. End of problem and can be removed easily with a Allen socket. Bowls especially.
Steve

swest wrote: I replaced my screws with SS Allen head. End of problem and can be removed easily with a Allen socket. Bowls especially.
Steve

I agree SHCS's everywhere and anywhere they can be used.... I took the money I didn't waste on paper air filters and paid for the SHCS's on my bike :whistle:

:woohoo: