Home made carb sync tool

[VP1]

Time to sync my carbs. I bought the material to make this yesterday- http://650ccnd.com/mano.htm

My thinking is to sync carbs 3 & 4 first. Adjusting only carb 2 I then sync that carb to carb 3. Then adjusting only carb 1 I sync that to carb 3.

Not the easiest way, but probably the cheapest. But. Will it work? I think so. Howabout you guys?

-Todd

 

[Harry P.]

http://www.vfrdiscussion.com/forum/lofiversion/index.php/t16200.html

Check out this link...lets you do all 4 at once. Copy & paste to your browser. I made one for like $15.00 seams to work fine.

 

[Agemax]

dont think it will work mate, you need to balance all 4 carbs at the same time, adjusting one carb will affect the others as you balance things up. for the price of it buy 2 kits. connect one up to 1 and 4 carbs and the other to 2 and 3. this may be a bit more accurate but you cant beat a proper set of vacuum gauges to do the job properly IMO

 

[VP1]

I like the four tube home made system. I could make that with what I have on hand and I think I will!

 

[Steve]

That method works beautifully for two-cylinder engines. By the time you add two more cylinders (and carbs), things change drastically. One member here developed a method that uses only one gauge, and uses an aquarium manifold to switch between the carbs. I had the opportunity to check his carb sync with my mercury sticks and found it to be remarkably close. So close, in fact, that I did not want to chance messing it up by trying to fine-tune it. Having done several sets of carbs with a multi-column (SIX :dancing mercury gauge, I can tell you that if your bench sync is remarkably close, you might get away with it. If, however, there is quite a difference between any two carbs, you will be chasing your tail for a long time.

The Motion Pro unit from Z1 is $84.37. Shipping to my house is $6.16 (USPS) or $7.78 (UPS), giving a total of $90.53 or $92.15.

With the current exchange rate, the Carbtune is about $86.95 delivered. If you add the storage case, that goes to $97.45.

In my little pea-pickin' mind, it's an easy choice. Go for the Carbtune. Yeah, it costs more than the home-built one you are wanting to build, but the $75 difference in price will buy you a LOT of sanity.

.

 

[Nessism]

2-3 need to be balanced first. After that, you set 4 to 3, and 1 to 2 - in no particular order. You may need to pull off the sync gauge a few times and move the tubes around but it should be doable.

Good luck.

 

[VP1]

If, however, there is quite a difference between any two carbs, you will be chasing your tail for a long time.

.

Which is EXACTLY what I've been doing for the past 2 weeks. Dear god, please let it be that I only need to sync my carbs. However, they do look to be very close at least visually..

 

[Agemax]

dont mean to rock the boat, but in my experience as a trained m/cycle mechanic you cannot accurately balance 4 carbs in "stages". they all have to be balanced at the same time, using 4 seperate gauges, if you want it to be accurate.

 

[Steve]

Here is what the factory manual for my 850 says:

.

 

[VP1]

So I made my carb sync tool tonight. I ended up making some threaded tubes that will thread into the carb sync port. Found some aluminum tube at the hardware store and bought a 5mm die which I used to thread the tube. I'm going to use a little thread tape on the aluminum tubes and screw one into each sync port, then I'll slip the clear tubing over the aluminum tubes. Planning on using motor oil as the fluid in the tubes.

I'll post the results tomorrow.
If this doesn't work, I'm sorry to say that I will be taking it to a shop to let them diagnose it. I've already dumped far more money than I had anticipated on this bike trying to get to the bottom of the the unstable idle(cleaned carb, replaced o-rings, sealed airbox, replaced intake boot o-rings) and I just want to ride the damn thing!

Wish me luck, and as always, advice is appreciated.
-Todd

 

[VP1]

Picture of the aluminum fitting I made

 

[Harry P.]

just be careful at start up and keep a close eye on the levels and a finger on the cutoff switch, so you don't suck the oil in.
Take your time as the turn of the screw may take a bit to show on the manometer. I'm sure you have a strong fan to blow on the motor as you're doing this as well.

 

[Nessism]

Sounds like a good project. Good luck and keep us updated.

Back when mercury was available I made my own sync gauge using pito tubes down into a container of mercury. Worked great and saved me a bunch of money over store bought gauges.

Regarding the fluid you are going to use, why oil? Water is heavier which is what you want I think. Maybe use some anti-freeze? The Motion Pro gauge with the blue fluid uses something very similar to anti-freeze or so I've been told.

At any rate, good luck.

 

[waltergs1000]

I built this. in Italy is all in hydraulic - air pressure - compressor shop. Do not see but a half pipe there is a valve that close air passage to adjust the hand of the instrument, This also synchronizes with each other instruments

excuse for bad English translation google

ciao da Italia!


http://img187.imageshack.us/img187/843/vacuo1lw8.jpg

http://img383.imageshack.us/img383/4430/vacuo2ey6.jpg

http://img78.imageshack.us/img78/1935/tubira6.jpg

 

[Nessism]

I built this. in Italy is all in hydraulic - air pressure - compressor shop. Do not see but a half pipe there is a valve that close air passage to adjust the hand of the instrument, This also synchronizes with each other instruments

excuse for bad English translation google

ciao da Italia!


http://img187.imageshack.us/img187/843/vacuo1lw8.jpg

http://img383.imageshack.us/img383/4430/vacuo2ey6.jpg

http://img78.imageshack.us/img78/1935/tubira6.jpg

Nice work!

Gauges like that will work fine. Before you do the sync you need to calibrate each gauge by hooking it up to the same vacuum source - similar to the factory Suzuki tool.

Dial gauges will also have a lot of needle fluctuation during the sync job - you need to sort of average in the center of the fluctuation. Inserting a plug with a small hole through the center into the vacuum lines will help act as a damper and slow down the needle movement. This is also recommended for use with just about any type of gauge - Motion Pro provides these plugs with their gauges.

Lots of different ways to achieve the same goal.

 

[jpaul]

dont mean to rock the boat, but in my experience as a trained m/cycle mechanic you cannot accurately balance 4 carbs in "stages". they all have to be balanced at the same time, using 4 seperate gauges, if you want it to be accurate.

It's not so much that it's impossible, but it's definately more trouble than it's worth. The procedure that Nessism outlined will work, but you will need to go through the entire procedure at least twice, and possibly several more times, hopefully not making an adjustment on the second or third time that undoes everything done to that point. For the price of extra tubing, make one that does 4 cylinders at once; unless you think your time is worth next to nothing.

 

[Agemax]

well said jpaul. a 4cyl set of vacuum gauges is not dear to buy. just plug em in, fire it up and set your carbs. self damped gauges and deadly accurate. far less time, hassle and grief than trying to lash up a home made set that you cannot gaurantee. just my opinion

 

[Spyder]

Vacuum gages are cheap @ a hardware store IE. Home Depot, Lowe's, Manards... Most vacuum gages have a tiny hole in them to reduce the fluctuation. four gages and a few fittings, a couple feet of hosing. Shouldn't cost anymore than 40 us dollars.

 

[VP1]

Got the tool all made and worked a little with it this morning. Raining out here in San Francisco so I wasn't able to do too much test running. The tool itself seemed to work pretty well...well until I burned through one of the tubes with the header and introduced air bubbles into my carefully de-air bubbled system. Doh! I'll have to let it sit again for a few hours and let the bubbles work their way out. Gotta get some longer fuel line too so I can get the tank out of the way properly.
I cut the burned section off of the tube (about 1 foot came off). I wonder if having one tube shorter than the others will affect the reading..I don't think it should..

 

[VP1]

Oh I did notice something though. When I fired up the engine I found cylinder 1 to be not running (cold header). I adjusted the sync screw and fired it up again and the cylinder then started running like the others. I'm thinking that possibly my erratic idle may be from that #1 cylinder not always firing due to the throttle plate being too far closed. Then when I open the throttle that cylinder turns on (for lack of better terms) and after closing the throttle it still has enough fuel to make the idle high, until the closed throttle plate eventually chokes it off and kills that cylinder making my idle drop... Maybe it's just wishful thinking!
-Todd