Author Topic: sync adj screws  (Read 2818 times)

Offline yamahakaw

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sync adj screws
« on: September 04, 2015, 07:02:16 pm »
anyone know number of turns to turn out screws so I can start the bike to sync carbs.

Offline SteveJ.

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Re: sync adj screws
« Reply #1 on: September 04, 2015, 07:08:37 pm »
Set the idle to about 1100 rpm and go from there. Do 3 to 4, then 3 to 2 then 1 to 2
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Online turbojoe78

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Re: sync adj screws
« Reply #2 on: September 04, 2015, 07:14:01 pm »
The sync adj screws should only be adjusted with some kind of sync tool hooked up to the carbs and the bike running.

You don't touch them from there current position unless you have the carbs off the bike and your giving them a bench sync to get them close, and they should still have the final adjustment done after installed, with some kind of gauges and the bike running.

If your asking about the air idle adjustment screws, most people are turning them out 2 turns from fully seated with stock carbs.
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Offline redzgrider

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Re: sync adj screws
« Reply #3 on: September 06, 2015, 02:11:03 pm »
Can't find the .pdf at the moment, but the key thing is to adjust the screws on the bench while you can still see the butterflies. You want to adjust the screw so that each butterfly is open the same amount, as I recall it's the last transition port on the floor of the air path you want to work with, and you want each carb to expose just about one half of the port.

Offline MAN OF BLUES

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Re: sync adj screws
« Reply #4 on: September 06, 2015, 03:57:46 pm »
that's kinda correct....
I wrote this explanation in my Concourier article entitled Carbs. it ain't a diet thing

with the carbs in front of you, turn the main idle adjust knob while watching the throttle plates till the screw stop is just touching the stop lug, and then back off another half turn. this insures it has no effect on the individual carbs when adjusting the screws.
they should all be fully closed, and covering all of the holes in the throat behind the air mix needles, if not, adjust each screw untill this occurs
start with the middle screw first, then the 3/4 screw, and finally the 1/2 screw.
now you may begin adjusting them untill all of those butterfly throttle.plates begin to show just the leading edge of the first/front most hole in the throat, you just want it to begin being seen, takes a keen eye... continue untill all 4 look the same.
Now you may twist the idle speed knob untill you see the edge of the plate move them all so you see its.edge at the center of the holes, this is tricky, but if you ;) ;) do it correctly the reflection of the hole on the plate will make it appear as a circle, not an obround or figure 8 shape. if you need to tweak individual sides at this point to get them alligned, so do so, but they should all alllign if the first step was done right... somtimes it doesn't due to rod flex on the shaft, or wonky springs..... now open the throttle by manually actuating the lever, and let them all slam shut,.repeat this a couple times,.and verify that the leading edge of all throttle plates are.all centered.on that front most hole.... now, don't touch anything..... install the carbs, and procede to using a manual gauge for final synch, but I will tell you this...
on a perfectly cleaned set of carbs, with new air screws and hardware istalled, this bike should start, and idle perfectly... depending on you valve adjusts, and airfilter, you should not have to turn any adjustment screw more than 1/8 turn, and when I say this, when you have a quality synch gage on them, Like a TwinMax set on medium resolution, simply inserting the screwdriver into the screw without any pressure, will show a change...
I've built a lot of Keheins on my bench, and installed them, and never had to tweak a screw more than a "twitch"...
mind you Steve has built a lot more than I have, but I'm sure he knows my secrets as I've freely shared them with him...

the procedure I outlined will insure the bike WILL start, and will amaze you.... it ain't rocket science, its just carbs....  :rotflmao: :chugbeer: :chugbeer: :hail:

30 YEARS OF KAW.....

Offline yamahakaw

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Re: sync adj screws
« Reply #5 on: September 07, 2015, 08:05:22 am »
got it done and runs good now.

Offline tweeter55

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Re: sync adj screws
« Reply #6 on: September 07, 2015, 07:21:16 pm »
got it done and runs good now.
OK...OK...someone had to do it...
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