1 quick carb synch ?

ok i got everything done but the synch on carbs!

i see it says for a basline use a 1/8 in drill bit then adjust as needed! right?

ok do i put the 1/8 bit on the airfilter side of carbs or on the motor side?
i assume the airfilter side as thats were the air is let in the carbs (but not sure), so ill ask a member!

Post edited by: steveo_4192003, at: 2006/07/11 11:43

I went by the airfilter side, but i'm knew to the carb thing. But i think i have a pretty good idea of it all.

should be the motor side. your adjusting the butterfly valves to match each other.

btchalice wrote:

should be the motor side. your adjusting the butterfly valves to match each other.

Except that if he has the stock 77 KZ650 carbs they don't have butterflies as they are not CV carbs.

To answer the original question, it don't make any difference, you are only adjusting the slides to be equal to each other, so as long as you adjust them all from the same side you will be fine.

yeah i did mine from the front and they seem to be okkeedokee:whistle:

The way I understood it is that this method is not for synching the carbs. It is just to set the slide height. With the 1/8th inch bit or wire the same size you want the slide set so that the bit or wire falls out as soon as the throttle is moved a little bit. This insures that the slides are set all the same way. Synching is done by adjusting the air screws. I might be way off though. George where are you?

It's called a bench synch, it gives you a baseline for the final synch using a manometer and gets you "close".

ok i was reading in the file base for kz 650, that i should use 1/4" drill bits or four pices of metal coat-hanger!
also says to do this on engine side of carbs!


second opinion would help out!!!!

Just look at the drawing you posted, it's pretty obvious that you want to stick the drill bit/etc under the low side, if you stick it under the high side then the low side may be resting on the bottom of the carb. It really does not make much difference which way you put the drill bit in, as long as it extends under the low side, probably be easier to do it from the engine side though. All you are doing is setting all the slides at the same height.

Bench sync is to get the carbs close enough to where they are able to be synchronized with a manometer AND to get the slide height related CORRECTLY to the idle speed screw setting. The 1/8" drill bit makes it impossible to get the slide height related correctly. BUY A FACTORY SERVICE MANUAL and follow the procedures they outline. There is a reason that they don't use drill bits. The drill bits get all the slides the same height accurately BUT the slides' adjustment will be either on the fringe of where they should idle or outside the range where the proper idle can be set. To bench sync, you don't really need 1mm wires... you can eyeball...

First, loosen the locknuts on the adjusters. Then use the idle adjust to screw it to about 1/3 the way that it can be screwed in. This will leave about 1/8" to 3/16" between the butterfly stop and butterfly itself on the engine side of the carbs. Then adjust the slides so that you have about 1mm opening. Use the idle adjust to close the slides and see if they all close evenly and then open them so that there is a bit less than 1mm opening and that will set the inital idle speed about right.

once agian ,this site/people helped me out
thanks all!!

i couldnt get it to idle right after i did the bench synch w/ drill bit!!!
i will now eyeball, or try 1 mm wire for the next try and try agian

i see these bikes came w/ a few models of carbs! slide , butterfly, ect..

i have the slide/barrel version and i.d them as mikuni vm24s, stock on my 77 650b-1

thanks all
( out to the garage to try agian!!! )