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I sync'ed my throttle bodies the other day so thought I would do a write up on that. There is already a huge discussion from days gone by on the topic here http://www.rswarrior.com/forums/21-how-tos-general-maintenance-tips/133498-how-sync-throttle-bodies.html There are some really good pics there also that might be helpful if something here isnt so clear.

1) Remove gas tank.
From here things can get tricky depending on if you have done a V-BAK or if you have a meter or you are using a home made meter. I have a Morgan Carbtune II and a homemade VBAK so the write up will be for using that.

2) I cut a 2ft length of 1/8" tubing and put it on the nipple coming off the back of the throttle body just behind where the throttle cables hook up, this would be on the same side of the bike as the clutch.

looking down from above


3) Now I found the sensor that has the grey connector going to it. If you have done a VBAK hopefully you kept all your vaccum hoses going to the same sensors so this will work. I pulled the vaccum hose from this sensor and installed a t fitting. Then a short piece of tubing to hook back up to the sensor. Now I cut a piec of tubing about 1'6" long and hooked up to the free spot on the T fitting. I cut it 1'6" to account for the approximate 6" of tubing already there so that both of the tubes I will hook up to my Carbtune are about the same length.



4) I hook both of these tubes we just installed up to my Carbtune and started the bike. I let the bike run for 5-10 minutes to get good and warm.



5) Now that its good and warm its time to sync everything. Now I tried to sync things at about 1,500 rpm. I have read where you should do it at idle or at higher rpm's. I couldnt do it at idle because its to difficult to see with the carbtune. The columns jump up and down to great to see of its sync'ed. At about 1,500 they werent jumping nearly as much and it was more stable so thats what i sync'ed at. The adjuster screw is just to the left of the one tube you hooked up on the throttle body

I would turn it an 1/8" at a time then blip the throttle wait a few seconds and see what changed. Then turn the screw more or less depending on what happened.

Once everything is as close as you can get it take off the tubes you put on, remembering to put a cap on the nipple and the T fitting, or just take the fitting back out.

Then put the tank back on and you are good to go
 

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Good write-up. There's also steps in the service manual beginning on page 3-15 which will cover all-stock bikes for the vacuum line connection points.

I have been using the same sync tool, it works well. With the VBAK I noticed if my idle was under spec then the gauge jumped a lot so now I check warm idle rpm and adjust first. Then I did my best to adjust with rpm at warm idle, and then I'd blip the throttle a couple times and then let the gauge settle down a couple seconds at warm idle then I throttled-up to about 1500 rpm to see how steady it was there. It took time to get it.

I also found out its not so important that the vacuum lines be precisely the same length, but it will take a second longer for the gauge to settle down. In the end, having mods, I installed vacuum lines creating equal length runs that terminate protruding out from under the fuel tank under the rider seat. I plugged each hose into a normal plastic vacuum-hose-splice and put a heavy nipple on the open ends where I can get at them. I still have to remove the right side cover to get at the adjustment point. But to plug-in the carbtune I just lift the rider seat.
 

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5) Now that its good and warm its time to sync everything. Now I tried to sync things at about 1,500 rpm. I have read where you should do it at idle or at higher rpm's. I couldnt do it at idle because its to difficult to see with the carbtune. The columns jump up and down to great to see of its sync'ed. At about 1,500 they werent jumping nearly as much and it was more stable so thats what i sync'ed at. The adjuster screw is just to the left of the one tube you hooked up on the throttle body
It looks like from this picture you're adjusting throttle body #1 (back cylinder) when the manual (page 3-16) says to adjust throttle body #2. Is that correct?
 

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Monty ... Imho no big deal. Some of us have used the No.1 cyl adj screw only and some have used both for the Sync.
I would expect there are others around here that will confirm the above :)
 

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I couldn't sync my throttle bodies. I closed off both air screws and adjusted the butterflies to get close to 10mm difference. Then, opened #1 1-1/2 turns, then sync'ed #2 to #1.
 

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I couldn't sync my throttle bodies. I closed off both air screws and adjusted the butterflies to get close to 10mm difference. Then, opened #1 1-1/2 turns, then sync'ed #2 to #1.
Robert ... I've not had the need to adjust the balance screw for the throttle body plates but if the occasion arose i would probably use a round rod or wire gauge between the body and plates though I suspect your adjust is just as good and i like your logic closing both air screws :)
 
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