mechanical carb sync

[arse21]

Hey there folks
I will be either building a set of gauges at some point for carb sync. However having carbs on bench I can see #1 and 5 butterfly valves are more closed than all others. I've read you can use feeler gauge to check clearance and I wonder what size gauge to use. Wanted to set mechanically for now

[98valk]

middle carb right side is the base, its not adjustable. so adjust all to match that one.

[arse21]

middle carb right side is the base, its not adjustable. so adjust all to match that one.

With a certain size feeler gauge or measuring depth from bottom of butterfly out?

I intend on getting vacuum on it as well, just visibly out on 1 and 5 which have been my problem children anyhow

[WintrSol]

For a bench sync, many use a set of miniature drills (don't use the sharp ends), to find one that fits like a feeler gauge into #3, at the widest gap between the butterfly and carb barrel, then adjust the rest to that. You'll still need to test vacuum, but, at least, you will have a head start. For carbs without vacuum ports, this is as good as it got.

[rug_burn]

    I did a bench sync on mine last time i had the carbs off.   I did it by eye, comparing the gap to #3's gap when closed, and it actually came out real close when I synched them using a vacuum gauge.    Actually, it might have been a little better.   I wouldn't be surprised if they just match all the gaps between the throttle plates and carb bore when they assemble the bikes for the first time.
     
   I was thinking what might work well woud be to make a thin spacer, for example using a small nylon zip tie so as not to scratch or ding anything.    Then thin it out a little with a mark on it to match  #3's gap, to get the same exact thickness for every plate.    That would probably beat my vac. gauge setup, which is admittedly pretty crude.

[arse21]

    I did a bench sync on mine last time i had the carbs off.   I did it by eye, comparing the gap to #3's gap when closed, and it actually came out real close when I synched them using a vacuum gauge.    Actually, it might have been a little better.   I wouldn't be surprised if they just match all the gaps between the throttle plates and carb bore when they assemble the bikes for the first time.
     
   I was thinking what might work well woud be to make a thin spacer, for example using a small nylon zip tie so as not to scratch or ding anything.    Then thin it out a little with a mark on it to match  #3's gap, to get the same exact thickness for every plate.    That would probably beat my vac. gauge setup, which is admittedly pretty crude.

I ended up making 2 slight brass shims, one to gauge the gap on 3 and them adjust all others to the same feeling pulling the other shim into the other carbs. She runs beautifully now though I will look to get a vacuum on it soon to ensure it. Someone messed this bike carbs up baaaad. 1&5 jets were clogged and their butterfly adjustment was torqued all the way in. She's back on the road though!

[Mooskee]

Red Eye has a brass strip in his carb kits that is used for mechanical setting of the butterfly valves. I still use one when I rebuild a set. Just check the pull on #3, and compare it to the others to get a reasonable starting point. I also take measures to maintain a close setting on disassembly. For the carbs that have a tab connecting to the ajacent carb. I back the adjusters off 5 turns and remove the spring. When I reassemble, I put the springs back on an turn the screws in 5 turns. The mechanical bench set will get you in the ball park. I always put them on the test engine and balance with the Digi Sync. They always need adjustment. Mind you the Difi Sync accuracy and resolution provides an adjustment 16X better than factory spec requirement. If someone wants me to put a micrometer on one of the brass strips, I can. You could probably use a steel feeler gauge carefully.