Synchronizing when #3 seems to pulling all the vacuum

[Hummer]

First time synchronizer here and figured I'd post to see if I get a quick reply while I run out to pick up a carb adjustment tool for that pesky middle screw...

Where do I start when #3 is pulling all the vacuum? Small adjustments to the three other carbs until it balances enough for me to start tweaking? Just to confirm, turning the screws counter-clockwise should result in more vacuum and clockwise should lessen it, right?

Thanks - hope someone is feeling helpful over the next 20 minutes!

[chef1366]

Which screws are we speaking of? The ones on the throttle linkage right?

[1948man]

Yeah, the mixture screws are not for the sync.

[Gonzo]

Did you do a good bench sync on them?

[chef1366]

Twenty minutes are up

[BassCliff]

Hi,

Synchronize Carburetors
(With the Morgan Carbtune)

Synchronize Carburetors (bwringer's site)


Thank you for your indulgence,

BassCliff

[Hummer]

Haha...tough to avoid buying other new tools...

I'm working off the Morgan Carbtune tutorial but couldn't keep the bike going without sucking the oil out of my homemade manometer. Thought I started with a good benchsync...bike runs just fine. Manometer is telling me otherwise...

[Steve]

Just two thoughts going through my head right now:

... homemade manometer. ... Manometer is telling me otherwise...

Do yourself (and your bike) a favor, get a real manometer.

.

[Hummer]

Its on the list of tools to pick up. Oil in transparent lines seems to work quite well!

So the levels all seem to be the same at 2000RPM...another question though-does it make sense that the engine seems to run just fine with the air screw almost fully seated? Played with it before and after sync and it seems to be just fine from seated to about 2 full turns out. Tutorials say that optimal is turned in as much as possible so.....?

[Hummer]

I always prefer to leave threads resolved, if possible, so here goes -

The homemade manometer worked well for me. All I had was 4 seven-foot lengths of clear plastic tubing, connected to the Z1 permanent sync ports on my intake. I connected the set-up to a spare piece of plywood in my garage and filled each line with approximately a foot of gear oil. A quick online search for homemade manometer will bring up a few good pics for anyone interested.

Adjusting the other three carbs incrementally balanced them to #3. It doesn't take much of an adjustment to one carb to throw the other three into chaos. Idle speed obviously makes a big difference too, but I didn't realize how much of a difference there could be. In hindsight, it makes sense (and is likely common sense to any of you who do this regularly).

The mixture screw is a little more of a mystery to me, although repeated searches on the forum keep leading me to a favourable answer. There shouldn't be a big difference unless something is way off. With that logic, I'll leave them at 2 full turns out from seated.

The bike seems to run well - a few more miles on her should give me a better indication. I blew a weld on the shift linkage for my forward controls, so it was a short ride. There may be a bit of a fueling issue, as the bike felt a little jerky after a few shifts when I got on the throttle. The linkage broke as I was trying to figure that out. Hopefully more diagnosis time tonight.

Thanks for the help to this point!