Carb balancer tube

I bought a '79 KZ750 twin recently but haven't had much chance to ride it due to snow and cold temps.

I replaced the tach cable today which of course meant I had an excuse to at least start her up When I cut it off, there was a fair amount of vapor coming from around the carbs.

I took a closer look and it was coming from a little nipple on one of the carb holders close to the engine. The other carb holder had a nipple too but this one had a little plastic cap on it.

I couldn't find any reference to this in my service manual but from looking at the parts diagrams on Kawasaki.com it looks like there's supposed to be something called a balancer tube connecting these carb holders.

Can anybody tell me if I'm interpreting the parts diagram correctly? Is there supposed to be a tube between these carb holders?

If so, what exactly does it balance? What would happen without it (like my bike)? Would it affect idling or performance in some significant way?

Short of ordering a replacement online and waiting, can I replace this with some other sort of tubing (like fuel line)? and if so, anybody know what diameter it is?

not familiar with that model but Z1 enterprises has a carb guide section that might help you

Topper, these are the vacuum ports used for carburetor synchronization described in the manual(check adjustment - engine pg 19). It is also the port that is used if you have a vacuum fuel petcock (not standard on the 79 750 Twin). I have tried it both ways (separate plugs on each and both combined) and did not notice a difference. Fuel hose has worked fine for me. Reference picture:

Yes, it needs to be completly over the bead for no vacuum leaks.

Good luck
Jim

Well one of mine is capped and the other is open. You think that tube is about 1/8 inch?

No, it is larger than that. The small end of the brass nipple measures 5mm (.2").
7/32" or 1/4" ID hose will work. (5mm or 6mm if you like the measuring system the rest of the world uses).

Good luck,
Jim

Thanks Jim. My eyeball estimate on that was way off.

I happen to have some 1/4" fuel line I hadn't used for anything yet. I tried it on there and its just a hair big. It'd probably be OK with some little clamps, but the space is just too tight in there for clamps.

I think I'll try to find some 3/16" fuel line next time I'm in town. (That'd be about 5mm right?)

The fuel line thing decreases vacuum at idle/cruise, (as viewable with colortune/manometer) thus requiring more fuel and slightly larger throttle opening to achieve normal results.

Not a huge difference, just basically drops your mileage a bit.

Vacuum nipples should be capped off to prevent vacuum loss as per manufacturer. They are for testing and balancing purposes only, and should never allow a decrease/loss in vacuum to occur.

You can make caps easily. Slide an appropriate size fuel line over the nipple, then cut the line leaving some excess to thread an apporpriate size bolt into it, to plug line.

Best of luck!

Thanks for the help. I picked up some 3/16" fuel line at the auto parts store and it seems to have done the trick. Fits over the bead and stays on without clamps.

I wonder how much this was effecting idling stability. Like I said I haven't really been able to ride this bike since its been too cold and icy. But it was idling a little rough and would occassionally backfire then die.

I figure a carb cleaning is needed before spring comes around. But that vacume port being open couldn't have been helping anything.

i have the same bike...and noticed the tube when i just cleaned my carbs and put em back on....

i figured it was a balancer as i have one on my quad also...

thanx for confirm