Carb Sync.?

[Bob Kelly III]

OK Stupid question .... where is the How to make the vynal hose carb syncronizer at ?
I've looked all over and I can't find it.
I think I could figure out how to make one myself but I prefure not to suck automatic trans fluid into my engine should I be wrong ....HEHEHEHEH !
I have a UNI-SYN carb syncronizer which only a few of you have probably ever hurd of ... its a aluminum cast large washer with a rubber pad on it for placing on the carb intake. it has built into it a venturi that has an adjustable plug in it's center, you adjust the plug in and out to raise or lower the amount of vaccuum for a reading... the reading is taken from a bolted on sight tube with a small light plastic cap .... the sight tube has to be vertical to work the best otherwise small adjustments won't effect it.... the problem with using it on the XS650 is that the sight tube is on the left which is great when adjusting the right cylinder but bad for the left as it hits the down tube between the carbs....
so I figured I'ed make a carb syncronizer for the XS650 and not have to guess at the angle I am holding it on the left side and try to reproduce the same angle for the right... ( which by the way seamed to work very well) ... but I want to be more accurate than guesswork !
I have seen many carb syncronizers in the past, most are rediculasly expensive.... and their just clear tubes with a heavy liquid in them some have valves at the ends that must be set to certain openings for diferent bikes....
I do know that you don't touch the throttle when Using the Murcury filled ones unless you want to have the murcury sucked into the engine.... so that probably goes for the oil filed ones as well.
I would prefure to have NO oil or water or anything else, but a floating indicator that is trapped so it cannot get out....
if you can point me in the right direction to find Travis's carb sync-er I'ed appreaciate it .
or perhaps you have a idea to make one that would not have the danger of the indicator being sucked into the engine.... that would be great as well....
there is enough Inovateive people on here that surely some of you have figured this out already !
and hopefully you would like to share how to make it and use it !
Thank you very much !
Bob............

 

[DanielBlack]

Bob, you're looking for a DIY manometer. For what it's worth, I use Stabil. Red, easy to see, and harmless if a little gets sucked in. Mine is just straight tubing, no jets or valve.

My tubing says 3/16 ID x 5/16 OD Food Grade, purchased at a Automotive store. In other words, it's not gas line grade.

Red and Green shrink tube was just an idea to identify the left and right tube. I know too much time on my hands and way too much over thinking.

10' loop for the fluid and the second 10' piece cut in half to add 5' to each length. At the joint is where the jets go.

Other clear tubing is very tight on the 5/16 OD. Stuff I had laying around and the jets fit inside this tubing very snug.

I like the jet idea because I know each are identical in size. Turning a valve leaves one open more than the other, perhaps it doesn't make that much difference.

A few holes in the yard stick to hold the tubing and you can use wire ties, bag ties or simple copper wire to hold the tubing onto the stick.

You will find they are extremely sensitive when adjusting carbs with separate cables like round slide VM Mikunis. Way more so than mercury tubes.
..

 

[MaxPete]

Daniel - do you have a photo of the Stabil unit? I'd like to sync my carbs and am looking for a good tool to do it.

I saw the manometer unit used by Brassneck on his bikes. He made it himself and it is very simple and effective - but I also looked at the Dellorto-Weber unit (www.amazon.com/Carburetor-Synchrometer-Weber-Dellorto-Mukuni/dp/B00SLH03R4) and found it attractive due to its small size and clear read-out.

Any thoughts?

Pete

 

[grizld1]

The DIY fluid (ATF, motor oil, etc.) manometer is a touchy item. Even if synch is fairly close, and the motor at low idle, you need to keep a thumb on the kill switch to prevent the high vacuum side from sucking fluid into the motor; you'll wind up shutting down when one side starts to spike, making a little adjustment, and firing up again, and you'll spend a bit of time getting bubbles out of the fluid, trying different restrictors to damp the action, etc.It's cheap, it's fiddly, and it's very accurate. I don't know of any DIY dry manometer design. If you want "no oil or water or anything else," get a Morgan Carbtune manometer; it uses stainless steel rods as indicators. Google for the URL; the price from the manufacturer, shipped from England, is very reasonable, other vendors sell high. Your other option is dial gauges: IMO the cheap ones aren't worth the trouble and the good ones are expensive.

 

[retiredgentleman]

Its very simple to make a manometer. 22 feet of 3/16" ID, 5/16" OD plastic tubing. fasten the tubing in a U shape on any piece of wood that you have handy. I have used Stabil, but any liquid can be used. No valves or restrictions needed.

Before using the manometer, you must do a bench sync of the carb butterflys. With carbs on the bench, you use a slip of paper as a feeler gauge. Cut a piece of paper about 3/4" wide and 3 or 4" long. With both butterflys almost fully closed, slide the paper feeler gauge under the butterfly, and adjust the centre screw between the carbs until you have equal drag on both butterflys.
This will have the sync very close.

If you don't do the bench sync first, then you run risk of sucking the liquid into the engine.

 

[grizld1]

Pete, I assume that you realize that to use the unit you linked to, the stock air box would have to be removed to poke the business end of the instrument into the intake bell? Would there be interference with the backbone of the frame? Hard to tell.

 

[DanielBlack]

Pete, my manometer looks just like the one RG posted.

Yes, fiddly, and touchy when beginning the process. Even with the bench sync, this thing is accurate. I appreciated the Stabil, from experience watching it get sucked in immediately at first startup. But this recent time when I hooked it up it was still spot on and perfectly balanced. I could've used water or battery acid, it was that balanced.

 

[weekendrider]

 

[MaxPete]

Some great ideas here - many thanks folks!

I finally figured out that Daniel was referring to his working fluid as Stabil - rather than water or mercury etc. and I sure do understand the necessity of NOT allowing fluid to be sucked down the throat of the carb. That lack of a working fluid is what attracted me to the Dellorto-Weber unit. It actually looks pretty slick - but Grizld1 is quite right in that I may not be able to fit it into the frame where the downtube goes. Also, removing the stock airboxes may affect the reading if the airboxes are not perfectly symmetric (and they likely aren't).

I know that I got lucky when I resurrected Lucille. I rebuilt the carbs, but carefully didn't disturb the linkage between them, and she seems pretty well synchronised at this point. My concern is the '81 Special-to-Cafe bike, which I do not yet have running. I am not confident that the carbs are right on it and so a synchro job is likely in the cards.

I may actually buy one of the British units as I also need to take a look at the throttle bodies on the ST1300 (it is EFI) - and it would require a 4 cylinder sync.

Cheers,

Pete

 

[retiredgentleman]

Pete, my manometer looks just like the one RG posted.

Yes, fiddly, and touchy when beginning the process. Even with the bench sync, this thing is accurate. I appreciated the Stabil, from experience watching it get sucked in immediately at first startup. But this recent time when I hooked it up it was still spot on and perfectly balanced. I could've used water or battery acid, it was that balanced.

Yes you only have to do the bench sync, after you have done work on the carbs, such as change the butterfly shaft seals, etc.. Once you have done it, the sync is close enough, does not change, and you can use the manometer anytime, with no fear of seeing the fluid disappear into the engine.
Its very simple, cheap and very accurate.

 

[retiredgentleman]

Pete..................4 cylinders.................no problem, just use 4 legs of plastic tubing.

 

[MaxPete]

Yup - thanks RG.

 

[fredintoon]

I use ATF because it's a nice easily seen red colour and won't do anything harmful bar making smoke if it gets sucked into the engine.
Be aware that an oil-filled manometer is at least ten times as sensitive as a Mercury-filled manometer so taller is better, using a 5 foot
long stick would be about right.
And if you really don't want to suck fluid into your engine, add a catch-pot to the top of each leg that's big enough to hold all the fluid.

 

[5twins]

I have an ancient original mercury filled "Carbstix" and it works very well. It has no valves or reducers but doesn't need them, probably because the mercury is so dense or heavy. Also, all 4 tubes pull from a small common reservoir at the bottom. Having this larger amount of liquid to pull from may help too. I thought about building a D.I.Y. oil filled one but I would incorporate a few "tweaks" based on the Carbstix design.

Instead of one long tube with oil in it, I would use a reservoir at the bottom of the yard stick. I think a plastic mayo jar maybe half filled with oil would do. I would stick 2 short brass tubes down through the lid into the oil. The hoses would attach to them on top of the lid. The yard stick would attach to the lid top as well, probably with a short length of small aluminum angle. For fluid, I'd want something heavier than ATF, probably 2 stroke oil I'm thinking. I'm hoping the heavier fluid combined with the larger amount of it would better control or protect against it being sucked up into the carbs.

 

[fredintoon]

Hi 5T,
thicker oil is more viscous and a more viscous working fluid will decrease a monometer's sensitivity.
But manometer accuracy is a function of the working fluid's specific gravity and all oils are about the same, somewhere around 0.8
Water at an SG of 1.0 gives a slightly shorter fluid column difference for the same pressure difference.
Carbstix Mercury's SG of 13.4 means that it's only 1/16th as accurate as an oil-filled manometer.

 

[TwoManyXS1Bs]

...And if you really don't want to suck fluid into your engine, add a catch-pot to the top of each leg that's big enough to hold all the fluid.

http://www.xs650.com/threads/homemade-carb-sync.2317/page-5#post-417944

 

[Paul Sutton]

Another problem with Mercury is it will amalgamate with other metals. Aluminium is a big issue as the amalgam forms very fast and in the presence of oxygen the amalgamated Aluminium converts to the oxide rapidly. If you have a spare drop of mercury place it on some Aluminium and observe what happens over a couple of days. Youtube has some videos which are safer to watch.

 

[MaxPete]

Another problem with Mercury is it will amalgamate with other metals. Aluminium is a big issue as the amalgam forms very fast and in the presence of oxygen the amalgamated Aluminium converts to the oxide rapidly. If you have a spare drop of mercury place it on some Aluminium and observe what happens over a couple of days. Youtube has some videos which are safer to watch.

Yup - I had thought of that too Paul. Handling mercury is really not for home-amateurs like me I'm afraid.

 

[Bob Kelly III]

Thank you for all the replys !
2M gave the best responce I think with an easy and accurate one that keeps the fluid in the device !
on another thread that he linked to I replied there only to discover it's quite old ! LOL typical for me ! LOL
anyway.... a loop of 3/16" i.d. vynal tubing a board and 2 small containers for the upper resivour is all that's needed
I sujested that the U-Tube Sync'er is so sensitive because the vaccuum is fighting each other trying to pull the liquid one way then the other
and even just a small imballance would pull it one way very quickly....2M's addition of the resivours on top of the U's sape cure any liquid from entering the engine.... but it still maintains the need for the paper sync-ing on the bench.... ( i think with the resivours on it that no longer would be the case)
it may suck it up to the resivours at first but you could adjust it down and be good to go.)
I sujested a way around the U-tube by just making a single unit indipendant of the other cylinder being a can at the bottom (with a air vent) and the hose near the bottom with your fluid in the can.... hooked to the intake of the bike it would suck the liquid up the tube... another can at the top of the line to act as a resivour like 2M's to catch the liquid from entering the engine. thats all that is needed for one cylinder so you need another for the other cylinder..... and you could add as many as needed....
but I think I like 2M's version the best of all the sujested methods its easy to make and provides safty against sucking the liquid into the engine...
I don't think 2M will mind if I re post his design as it is a very good one !
I am currently making one....now if I can come up with 2 good containers for the resivours !!!!!!
Bob.......

 

[MaxPete]

Looks like a good rig Bob - please let us know how it works out.

Pete