Home made carb sync tool

[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

[KiwiGS]

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..

Hi mate,
I have a home made sync tool similar to yours. Dont worry the tubes do not have to be the same length.
What are you using in the tubes? I use water with food colouring. As it has a higher density than oil, just means you have a wee bit longer to hit the kill switch if things are out of wack.
Cheers

[VP1]

Thanks, I used motor oil but it is a major pain the butt to try and get all of the air bubbles out of the oil. I think I'll probably re-make the guage and use colored water. I'll post the results this evening.
-Todd

[Steve]

Quoted from above:

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.

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

Then, from my post above those:

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.

Now, I just have to ask ...
VP1, can you give us an idea of your expenditures so far, and how much time have you invested in your gauge project?

.

[VP1]

Sure thing!
Probably about $15 in materials. I did however spend around $20 on the 5mm die and handle though. Over all it probably wouldn't cost a whole lot more to buy the real thing. However, I am a starving college student working 2 jobs so every little bit of saving helps. Plus now I know how to make a manometer. My girlfriend thinks I'm down stairs measuring how manly I am

Oh and plus, the home made manometer can be had in about 15 mins while the real deal would probably take a week or two to arrive. I'm impatient

[KiwiGS]

Quoted from above:



Then, from my post above those:


Now, I just have to ask ...
VP1, can you give us an idea of your expenditures so far, and how much time have you invested in your gauge project?

.

Steve I know what you are getting at, and you are right. But...
Why do we have 25-30 year old bikes when we could, for a few more dollars, have a much newer one?
I have mine because there is nothing better than making something out of nothing and doesnt matter if it is a barn find GS or a home made sync gauge. Oh and I could not justify or afford a new bike, so my choices were limited.
If GS owners valued the time they spend on their bikes there would be some pricey GSs out there.
I made my "tool" for nothing, and didnt count the time becuase I enjoyed doing it. If it didnt work then so what? I would just buy a gauge, when I could afford one.
It did work and now I have that money to spend on something that I cant do/build myself.
Steve I am not having a go at you mate, there seems to be an idea that every body can go and buy new stuff when they need it. Some cant for many different reasons
Cheers

[VP1]

Yea sometimes I fight with myself over doing things the hard way and saving a buck or shelling out the extra money and buying the real thing. Personally, I enjoy working with my hands and learning how to fix things while not spending a huge amount of money. Sure it usually does take more time and effort but right now I have more time than money(by a very very small margin :-P )

[jmlcolorado]

I really like the fact pf doing everything you can yourself. It, in the long run, might save time and money. For example, say i want a tire mounted now so i can ride in an hour. I cant take the tire off, roll it to my local shop, expect them to mount it in a timly manner, and give it back to me.

I can mount the thing myself and save a penny doing so. (i can also balance it myslef)

Same goes with taking a thirty year old bike to a shop. Most guys wont or dont want to work on one because they ARE so old. As soon as you ho in for a "tune up" you'll walk out with a $1000 bill cause this stripped and that broke.

I value my time in the garage with my bike. Ive had the pleasure of completly tearing mine apart and rebuilding if from ground up and in the process, i've learned a welth of great knowledge that will carry me through my life on other bikes. Something no bill to a shop could pay for.

There are some that prefer a shop and there's noting wrong with that either. I just prefer nicks and cuts and greasy hands.