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Discussion Starter #1 (Edited)
This should be relevant to carbureted engines with 2, 3 or 4 cylinders. EFI throttle body bikes, review your repair manual's procedure. For 2005-2006 ZX6 TB sync CLICK HERE. A highly recommended Do-It-Yourself, especially if you can borrow someone else's sync tool. It is really that easy.

My used ZX-9r ran poorly at purchase and I performed an eyeball sync* myself last year to smooth most of it out, but it still wasn't perfect. I decided to perform a real carb synchronization and purchased a Carbtune Pro 4 (58 GBP/$85 shipped) after reading good reviews.

Following my Haynes repair manual, I warmed the bike up (140 degrees) raising idle to 1,500 RPM, turned it off, removed the gas tank, connected the sync vacuum tubes to their intake points (below each intake boot), started the bike, sync'ed cylinders 1&2, then 3&4, then left side to right side. That took a whole 2 minutes, so for good measure I fueled the carbs up one more time, blipped the throttle to 1,800 to reseat the butterflies and repeated. The Carbtune made this work out to be child's play.**

No more ruppity-ruppidity. She purrs like a new bike, holding right at 1,100 RPM. Throttle body synchronization theory says that the engine will start easier, run cooler, be more efficient, smoother, with better throttle response & power. :crazyloco

04/2009 1,000 mile update I had to sync her again after some 1/4 mile runs for a Youtube short vid. Dunno why. The science holds true. She runs cool & smooth, starts easy & is a joy to ride. She's very miserly for something so wickedly powerful.
I only wish I would have done this 6 months ago.

*The science behind cylinder vacuum efficiency depends on many factors other than carb/EFI butterfly position; pilot air screw symmetry, pilot circuit clogs/efficiency, minor discrepancies in piston and ring fit, valve opening gap, valve air flow efficiency, carbon build up, temperature, oil weight, etc. Therefore, the only way to accurately synchronize the draw evenly is to use a tool that can measure each cylinder's efficiency.

** Before syncing carbs, always set the pilot air screws symmetrically. If you suspect the pilot air circuit may be dirty, pull the screws, clean the circuit plumbing, set them symmetrically, then perform your sync.
 

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Discussion Starter #5 (Edited)
A visual to help

I get asked occasionally on how high each bar should be, to which I answer it doesn't matter.

Assume this look at the sync tool, where the '*' symbolize the vertical bars:

..........*
.......* * *
0) * * * * sorry about all the periods, it's the only way to line things up.

.........*
...* * * *
1)* * * * sync # 1 & 2 with the screw between them

.........* *
...* * * *
2)* * * * sync # 3 & 4

...* * * *
3)* * * * sync left side (1&2) to right (3&4)

Or pictorially --
When connected to a vacuum sync tool the discrepancies become all too apparent.

before


after



A word of recommended caution. For best results, get your carbs set the way you want first. In other words, set the idle mixture screws identically and set float heights first. Then sync your carbs. Done right, your ride should be dreamy. (See picture below showing the three synchronization screws).

 

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Amazing how easy things are when people actually try to do something themselves. I solute you sir! My sync pro is awesome and it's worth every penny!
 

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probably a dumb question but are the carbs on a kawi like the ones on my old honda where as num 2 carb was the base carb ie non adjustable therefore used as a base to set the rest?
 

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Discussion Starter #9
Always consult your repair manual for the exact procedure and tune your jetting prior to the synchronization, but chances are your four cylinder ZX-11 has the standard three balancing screws as shown <here>. And therefore the answer is no. There is no carb that is the master to which all others need to comply.
 

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Always consult your repair manual for the exact procedure and tune your jetting prior to the synchronization, but chances are your four cylinder ZX-11 has the standard three balancing screws as shown <here>. And therefore the answer is no. There is no carb that is the master to which all others need to comply.
Is this the tool that I should be purchasing???

Carbtune ll 4 port carburetor synchronizer




Do I need anything else to go with this???
 

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Discussion Starter #13
Also look for the clear plastic restriction tube pictured below. Without it you'll have no way to get a steady reading...perhaps why this guy is selling it...'hey man, it doesn't work right....' ...No kidding. :angry Ever try reading the assembly instructions. :headscratch

The tube is cut into four equal ~1" lengths and inserted into each black vacuum tube, so it goes black tube, clear, black tube.
 

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It takes about twice that on the 2002 zx9. The screws are at the front of the carbs and you have to take the airbox off to get at them. The middle one is a mother-*er to get at too.
 

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how did you get the tubes on the carb? I had the bike apart today and the vacuum take off points are buried deep under the carbs and I have no idea how to get them attached
 

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Discussion Starter #17
:headscratch The Carbtune vacuum hoses are attached, in order, to their respective intake vacuum nipples (#92150). You remove/pop-off the existing vacuum hose, attach the Carbtune hose, sync the carbs, then reattach the existing vacuum hose to its exact intake vacuum nipple.

Picture compliments of CyclePartsNation.com

 

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Yea I think I have the right hoses (3 brown hoses attached to 1 3 and 4 and a blanking bolt on no.2 but I cant get any access to them as they are really far underneath, is the zx9r different ?
 

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Discussion Starter #19
Oh yeah, sorry. I just assumed you had a 9. Different models will have different configurations. I know another rider had to order the 4th nipple just so he could do his. What bike do you have? I could look it up on CyclePartsNation to see your configuration.

Yup. ZX-9r is pictured above.
 
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