Author Topic: Po' Man's Carb Sync Tool? (Read 20493 times)

Airmotive · « **on:** August 24, 2005, 12:00:48 AM »

have a lookie:

http://www.powerchutes.com/manometer.asp

The man makes a good point: Who cares how much vacuum each carb is pulling as long as you can get it equal to its neighbor.

Anyone tried it?
(Regardless, I'm gonne give it a shot. I keep ya posted.)

jwalters · « **Reply #1 on:** August 24, 2005, 01:25:38 AM »

I've seen that before. The only problem I would have with it, is its only going to be able to sync two carbs at a time. That makes the process harder to get all carbs sync'ed properly. In theory, you could still sync your 1 to 2, then 3 to 4 and then sync your 2 to 3. However, I find it handy being able to see the relative pressure of all gauges at once, because they tend to creep a little throughout the sync process.

Then again, the "luxury" of looking at all gauges at once is quite a bit more expensive than the home build device.
I would go for it and let us know how it works. Ever better, if you could sync it with your home built tool first, and then verify your sync'ing with someones real gauge setup.

At the same time, I have to admit, I am using my Morgan Carbtune more than I ever thought I would. Between my bandito and my old honda CB, it gets put to a lot of use. So if you get some spare $$, it might be worth it to get the real thing.
Good luck!
jesse

Red01 · « **Reply #2 on:** August 24, 2005, 01:30:34 AM »

You can just make two EXACTLY the same.

Airmotive · « **Reply #3 on:** August 24, 2005, 06:03:03 PM »

Since the manual specifies synchronizing the 1 to 2, then the 3 to 4, then the 2 to 3, I thought this little thing would be ideal for the job. I found it curious that the inventor specifies using oil in the tubes. Seems to me water would be better. It’s more dense, less viscous, less messy, safer if ingested by the carbs or spilled on the engine.

Regardless, this looks like my weekend project. I'm getting ready for the Dallas-Manitoulin (Canada)-Dallas ride in mid-September. This is the one little routine maintenance project I've been neglecting...mainly out of sheer stingyness.

Airmotive · « **Reply #4 on:** September 03, 2005, 10:14:02 AM »

Well, this thing actually works!

Granted, it's not pretty...but pretty was never a goal.
1/2" (outside diameter) clear rubber tube...about 20-25 feet. Extra length won't hurt, as long as your water is in the middle of the tube. I.E. one carb isn't pulling through a longer lenghts of tube than the other carb.

I used my garage door track to suspend the tube.

As you can (hopefully) see in the photos, the water level gives a clear indication of pressure difference (Delta P). Since you're only syncing the carbs to each other, the delta P is all you need. Since I am using water as my fluid, a small delta P results in a large level change....when syncing the #3 and #4 carbs, the delta P was great enough to suck the water right out of my tube! No worries. I simply did some blind adjustments and hooked everyting back up and tried again. (That's the main reason I used water in stead of oil. Such a small amount of water won't harm anything.)

The biggest hassle was trying to hook up a remote fuel source. As you can see, I found it easier to simply leave the gas tank hooked up and work around it. (This is MUCH easier if the tank is nearly empty.)

Total cost...less than a buck.

Airmotive · « **Reply #5 on:** September 03, 2005, 10:20:14 AM »

I forgot to mention in the above post...

I used a bungy chord to keep the bottom of the tubing pulled tight. (see first photo) Otherwise, it tends to curl up and generally make a nuisance of itself.

Sven · « **Reply #6 on:** September 04, 2005, 06:07:29 PM »

I have read several recurring threads on carb syncing, and someone recently asked me if I "had done it yet"...I guess all the other boys have, (or at least claim they have, with that loose carb who hangs out behind the bleachers).

So, briefly, what they heck is it, and when would you need to do it? No need to give a full lesson in the steps at this point, just trying to see why it's one this site's most recurring themes.

Airmotive · « **Reply #7 on:** September 04, 2005, 11:34:36 PM »

Basically...

You have four carbs, each feeding its own cylinder.

You want each cylinder to produce 1/4 of the engine's total power.

If your carbs are poorly synchronized, one or more cylinders may be producing more (or less) than its fair share of the engine's power.

Syncing the carbs is simply the way you set all the carbs equal to each other. Poorly synced carbs can hurt fuel milage, performance and (Mostly) idle and off-idle throttle response.

Blue Skies,
JJ

Sven · « **Reply #8 on:** September 05, 2005, 10:19:44 AM »

Well, that's clear enough, thanks!

I guess they just get off-balance over time as a natural occurance/wear etc.

Johnny Strommer · « **Reply #9 on:** September 05, 2005, 06:23:25 PM »

I built the simple yard-stick carb balancer as described on several sites. Used jack-oil in the tube.

I can tell you that none of the 4 carbs on my wife's 600 were in synch with each other. 1&2 were way out, as were 3&4 to each other and to 1&2. The result afterward was a much smoother engine in the 5-6K rpm range. Much of the vibration of the motor disappeared and the throttle response was better.

You certainly don;t need a 4-tube unit to do this. In fact, it would be cumbersome having four tubes at the same time. Synch-ing 1&2, 3&4 and then 3/4 to 1/2 is fool-proof, and very accurate if you take the time to ensure the oil levels are precisely level.

I imagine the only thing you MUST NOT DO is start the bike with only one end of the tubing connected, otherwise you'll pull the oil into the carb...not the end of the world, but smokey and a PITA (luckily I didn't find out).

12sdrag · « **Reply #10 on:** September 09, 2005, 08:55:14 PM »

O.k, I have to ask, I like the tool, made one today at work to show up the outboard techs. $800 snap on set he had to have. Now for my question. My O-B tech. says all multi carbs systems have a base carb? So I got out the trusty clymer manual and it read #4 is the base carb and to adjust 1,2,3 to #4, but everyone says 1 to 2 - 3 to 4 then 2 to 3 ? I understand this is a comparison of vacuum, why not start with #4 to 3?

Airmotive · « **Reply #11 on:** September 10, 2005, 01:02:46 AM »

There's fifty ways to get all the carbs equal. The best way is the easiest way.

The Bandit has an adjustment screw specifically designed to adjust the 1-2 to the 3-4. I follow that route simply because that's what the manual specifies. There's likely be some obscure engineering reasons behind that process. (Why would the carb manufacturer design in the added parts and expense of the 1-2 to 3-4 adjustment screw for absolutely no reason?)

12sdrag · « **Reply #12 on:** September 10, 2005, 11:01:12 AM »

Quote from: "Airmotive"

(Why would the carb manufacturer design in the added parts and expense of the 1-2 to 3-4 adjustment screw for absolutely no reason?)

OK don`t get upset, I know there is more than one way to do this. Looking at the Clyer manual they state #4 carb has no adjustment. There are only three synchronization screw that adjust the # 1,2,3. My manual says nothing about adjusting 1-2 to 3-4. Please don`t think I`m trying to be a smart ass. I`m simply stating what the manual says I have a Clyer manual #M353 96-03 GSF 1200 page 81-82. I just what to make sure I do it right and I understand what I`m doing.

Airmotive · « **Reply #13 on:** September 10, 2005, 06:05:06 PM »

Oh no...not at all. I'm sorry my reply came across as sounding upset.

By saying "the best way is the easiest way", I really mean just that...whatever is the easiest way for you.

I'm using the Haynes manual, and it mentions nothing about the #4 carb being different. By the way, is yours a 1st gen or 2nd gen bike?

Daytona · « **Reply #14 on:** September 10, 2005, 09:29:10 PM »

Picked up a 20' roll of 1/4" od clear tube, $1.85 dabbed a hi-lighter marker in a oz or two of water, sucked some in the tube (that way it won't have the bubbles) taped it to a yard stick wedged on my bike, after removing the tank and rigged a fire hazard of a fuel source. Man were my carbs way out!!! had to crimp the hose, and adj the sync screw to stop my engine from running on hydro! 3&4/1&2 then just plugged in 2&3 for the last adj with center screw. DON'T forget the cooling fan cause this can take a few!! What a diff and i thought it was running great. Set my mixture screws to 2 turns out and its smoother than its ever been. Carb sync is the first thing the zuki stealer wants to do! $85 bucks thank you. And i would have thought it was a good investment after these results. If you can change spark plugs! and with the help you get here GO FOR IT!!! The small tubing and water with color (i didn't have food color!) "hi-lighter looks hi tech though!" is very touchy but when you get em close that is close enough!! DO IT or GET TOGETHER and DO IT use it as an excuse to have a meeting/ride after! Here is a link to a pic if anyone wants tooo!
http://img100.imageshack.us/img100/3285/picture0681og2iv23xy.jpg