building homade manometer - questions about sync..

I'm trying to make the 4 way design in the sticky'd instant start thread above. My questions....

has this been proven to work as well as normal vacuum gauges (i can't afford those, and I don't know anyone with them, so this is kind of a moot point, but I want to make sure my effort will be worth it.)

For those that didn't check out the thread above, the manometer consists of 4 pieces of clear tubing with a 4-way connecting them all together, filling with AT fluid, and letting balance out. Then manipulating carb sync until all of the levels are equal.

I'm going to use ricks improvised YICS tool consisting of clothesline soaked in Marvels mystery oil, will this work effectively?

The main reason for me syncing is because I'm having a rough idle problem, and it tends to die after about 30 seconds at stop signs. Should I sync at a certain RPM, or can I use some choke to keep the idle going, and then take it off when its a little more even?

Is it possible to do this with tank on? Or do I need to lift the tank to get to the sync screws?

I think thats about it? Thx in advance for help.

kellen

 

I've used a couple variations of the homemade manometer and my bike always runs better after I do the synch. In my opinion - it is worth the effort and time to build them.

Can't comment on the YICS tool mentioned - never done it.

Synch the carbs at idle with a fan blowing on the engine to prevent overheating. You will need to move the tank out of the way. I release the tank from the mounts and then put a 2x4 between the tank and the frame to allow me access to the synch screws while still keeping the fuel and vacuum lines attached.

FYI - I prefer the two port manometer because then I can keep the vacuum line attached on at least one carb intake boot to get fuel to the engine under "running operation" vacuum.

 

Don't make the same mistake I did with the fuel tank. I thought I was being clever when I pulled the tank and turned it 90 degrees setting it back down on top of the airbox. Worked great... until it vibrated off the bike. Hey, let me tell ya, once that thing started to fall, it went down faster than Pamela Anderson on Tommy Lee! (Crap! Did I say that out loud?!? )

All kidding aside, if you're going to place the tank like that, strap it down. Now I've got several dents to fix this winter.

 

okay, i actually bought two vacuum guages at harbor freight today, so i don't have to build the tool anymore, but thanks for the info. Correct my if i'm wrong, but you sync 3 to 4, 1 to 2, and then 1 to 4, right? I think this is what it says in the manual.

I thought of another question though...

since i have no colortune, what is the best way to get the mixture right? Just adjust for a week or so by checking plugs, or is there a better way? I used to do it on my VW Bug by listening to where the engine speeds up then drops back off, but that only had 1 carb... In essence, besides the colortune, what is a good way to at least get started with the right mixture...

thanks

Kellen

 

You may want to consult RickCoMatic's Old School Method of One Vacuum Gauge Carb Sync. You'll have to adjust his procedure to accommodate your extra vacuum gauge, but with two it should go faster.

There's another post about Colortune-less adjusting but I can't seem to find it. It's there... you'll just have to look.

 

Far easyer not to use vacuum gauge just use the oil method with a 2 tube setup. Doing 2 carbs at a time is less confusing. You need to keep the idle at a constant speed while syncing. Sync a small amount watch the levels even out, don't adjust more untill you wait to see how fast the level changes, you should be able to get spot on. The adjust mixture, then check sync again, do this several times untill the bike is smooth as.

Mixture can be set "by ear" you can adjust untill the engine stumbles then back untill the idle comes smooth. Requires good hearing.

Be careful not to overheat the bike.

 

how would the oil be easier? Shouldn't the adjustment be the same, except I'm looking for equal vacuum readings on the gauges instead of equal level in the lines right?

thx kellen

 

if you use two gauges, first assure yourself that they read the same with a
tee fitting

 

cool.... they came with one so that should work out....

 

do u have a link for that part
cant seem to find it on the site

 

Here's a possibly odd question, If I was to remove my carbs form the bike and say hook them up to my shop vac would it be possible to sync them that way? Or is the engine running required? What I'm thinking about is doing this over the winter when the temp in the garage is -20. I would think this is possible, or am I missing something critical?

 

Yeah, the engine.

Each cylinder is going to draw slightly different vacuum. You must set each carb to the cylinder it is mated with. Nice try, though.

 

Yep, What he said. Would work for a bench sync though. If you had some way of measuring the vacuum.

 

I thought that was going to be the answer, but it was worth a shot though :S

 

If you try to hook up a shop vac to all 4 carbs and bench sync with GASOLINE ! then the vapors will fill the canister and be touched off by the sparks from the brushes when it reaches the perfect air fuel ratio--BIG explosion, not just a pop!
I read in a car mag about a guy shop-vaccing rat "stuff" out of a 4 barrel.
A little suction on the venturi. . . BANG !