Topic: Quick Bench Sync Question

[mcswny]

So I bench synced my carbs tonight. I wasn't too happy with my most recent vacuum sync and wanted to start over with a bench sync. I had fiddled with them a bit while on a trip to have a stop gap problem for what turned out to be a little rust left over in my tank (now gone).

I set and locked down number 2 and then proceeded to st 1, 3, and 4. My question is both 1 and 2 are set with 2 threads above and 3 and 4 are balanced but they have 4ish threads showing above the lock nut. Is this something that I should be concerned about?

I'll then proceed to set the idle screw and the vac sync correct?

Thanks,
tim

[turboed13b]

how are you bench syncing? The thread counts don't matter just make sure the slides have an equal gap on all 4.

[mrfish2]

The number of threads showing does matter to some extent. Too many/few (can't remember which) and your idle set screw will become useless. Here's what Harisuluv had to say in another thread about bench synching:

Really the fool proof way to do this is (and I've been meaning to make a video of it for the longest time):  We'll use a 1/8" drill bit for the example tool from airbox side.  Get all the slides off "the deck" that way nothing will bind and throw everything else off.  Designate #2 the master.  Back off the idle screw so it's not making contact.  Now get the nut on #2 to where it has about the normal amount of threads showing like you want on your picture on the right (3-4 threads, 4 is good).  Now here's where the foolproof part comes in:  You have only set where you know the threads at the top are a perfectly acceptable Honda factory level.  None of the other slides are BELOW the level of #2 (which would mess this up).  Now, adjust #2 with the IDLE SET SCREW with your drill bit (just close).  Verify range of motion IN and OUT with the idle adjust screw (should be making contact with the stop when turning in and out for providing a reasonable range of adjustment).  Next, fine adjust #2 with your drill bit (or whatever).  Now you are going to have for sure the sync set IN RELATION to the idle screw.  In other words, you're not going to get them all synced to each other only to find when you adjust the idle screw it's not even touching and you have no adjustment!  Now all you have to do is set the rest to the same level as #2 (adjust each with the individual adjuster, you don't need to really mess with the main idle adjust now).  Easy!

[harisuluv]

yes it's not exactly fool proof though, just check for range adjustment after setting the first one

[mcswny]

Thanks for passing along James description of bench syncing.

I was using this guide
http://www.hondachopper.com/garage/carb_info/bench_sync/bench_sync.html

I'll go ahead and do it again just for fun.

[mcswny]

So I re-benched synced and everything seems to be good and in line. I tested adjusting the main idle screw in and out and everything still stays in sync.

Just wanted to double check I'll have enough of room for fine tine idle revisions once the rack is all attached, and won't end up with a too high of an idle.

I've attached a picture with (from left to right)
1. the main idle adjuster backed all the way out.
2. idle backed in 1/2 turn
3. idle adjust backed in 1 full turn. I just want to make sure I don't end up with too high of an idle like the last time.

FWIW I bench synced with James steps and with this http://www.hondachopper.com/garage/carb_info/bench_sync/bench_sync.html and ended up with basically the same sync

[lrutt]

Don't worry about threads showing so much. Use a 1/16" drill bit, set that under your number 2 so it just slides in and out (like setting valves). Set the rest of the slides to match.

Then set your mixture screws the same (1.5 turns) and install back on. Very very seldom do I ever have to make any further adjustments (assuming valves are set correctly and the engine is in good health).

Ooops, looked at the other doc mentioned and it uses the same method.

Between bench synching this way and bench setting timing, my motors always come out spot on and ready to go, never needing any additional tweaking.

[mcswny]

Don't worry about threads showing so much. Use a 1/16" drill bit, set that under your number 2 so it just slides in and out (like setting valves). Set the rest of the slides to match.

Then set your mixture screws the same (1.5 turns) and install back on. Very very seldom do I ever have to make any further adjustments (assuming valves are set correctly and the engine is in good health).

Ooops, looked at the other doc mentioned and it uses the same method.

Between bench synching this way and bench setting timing, my motors always come out spot on and ready to go, never needing any additional tweaking.

1.5 turns on the mixture screw? I've been working with maintenance bulletin #25 and they're saying start at 1 turn?

[mrfish2]

Read what they say here about the air screw, it's pretty spot on.

http://www.salocal.com/sohc/tech/carb/asmpg_mgs/jetgraph.htm

[mcswny]

Read what they say here about the air screw, it's pretty spot on.

http://www.salocal.com/sohc/tech/carb/asmpg_mgs/jetgraph.htm

Thanks Mr. Fish. I'll check it out.

[mcswny]

Well I vacuum synced tonight after the bench sync and she's purring like a kitten.