Sync carbs-gauge type?

[ron2830]

May have outsmarted myself on this one. 79 XS1100 Special, just got it about six weeks ago, certain the carbs need to be sync'd, seemed all I needed was four vacuum gauges, found some inexpensive ones with 3.5 inch display at $15 each with hoses, etc. these are dial type, with about 3/4 of display for vacuum, the other shows pressure for low pressure fuel pumps. Opened one, hooked up to #4 carb after warm up but dial jumps back and forth wildly, if I throttle up to about 4000 rpm it steadies out around 22 hg. Same on other carb vacuum ports. It was cheaper to buy the gauges than pay the dealer to do this but maybe it does take a "special" set of gauges for this like the Clymer manual states. Would a mercury stick type gauge work better for this, just found that in the tech tips?

I can return the other three gauges if the dial type wont work.

Thanks for any help.

[mro]

If you want to use the gauges, you will need to make a dampener?...

Get a 1 1/2 dia pvc pipe about 16/18 inches long. cap both ends and drill/tap two holes for threads to fit one "hose barb" and the gauge. This will slow the needle from jumping around so you can read it.

I use just one gauge and move it from carb to carb and then double check after I think there synced.

Merc sticks are probably the best tho.



mro

[ron2830]

Live and learn.....

just found the answer to my own question, searched JC Whitney and found the mercury sync tools just for motorcycles, this is where I got the dial gauges, should have searched first or posted here!! Oh well, I think I can return the other three unopened gauges and get a mercury stick, any advantage to one type or another? Thanks for any advice to a novice!

[mro]

merc stick easier to use


mro

[Ken Talbot]

I'd second what MRO says about mercury gauges being easier to use. You have four columns all sitting in a row next to each other and it is really easy to see if one carb is off. With round gauges, you'd be trying to make a mental note of where each one is while looking back and forth. Either way, you still need restrictors in the lines to dampen out the vacuum fluctuations.

[ron2830]

Thanks for the help, what is a good mercury stick to buy, any difference in function, saw some on line for around $50.

[DiverRay]

$50 isn't a bad price. They can go from $45 to $85. You may see a cheaper price online, but add shipping and how cheap is it?
Read the instructions that come with the carb sticks, don't rev the engine then chop the throttle when you have them on the engine, and they will probably last a lifetime.
Ray

[strom]

Merc sticks?! Gimme a break!
Stick with these, read the manual. I have a similar set, comes with a pre-installed dampener... sort of a clamp with a thumb screw to squeeze the hose. A ball bearing between the srew and the hose. A tad tricky to dial in the damper, but works magic. I have carbs synced within 30 minutes... including seat, gas tank removal and reinstallation.

LP

[ron2830]

Strom, found the guages I think you have

They are a set of four with the dampeners in the JC Whitney catalog for about $52. Are these the ones you have? My mistake was buying four basic vacuum gauges. Maybe if you had good luck with these I can do an exchange with them.

[JWSanders]

Since you already have them, might as well stick with the gauges. Go to an aquarium store and get a 4-valve air controller, or 4 individual valves (which may be easier to work with). Connect those to the 4 vacuum lines, and turn them down until the fluctuation is down to a 1/8" or so (of needle travel) from each carb. Once you set them they should be pretty much right from then on.

Wouldn't hurt to mount all 4 gauges to small board or something, too. Makes it easier to set them on the handlebars when adjusting the carbs. Will be exactly like the JCWhitney setup after that.

[xssiveone]

Re: Strom, found the guages I think you have

Originally posted by ron2830
They are a set of four with the dampeners in the JC Whitney catalog for about $52. Are these the ones you have? My mistake was buying four basic vacuum gauges. Maybe if you had good luck with these I can do an exchange with them.

Those are the ones I bought... mounted on a rack, with the dampers included. Not going to claim they are better, or worse, then the merc sticks, I just didn't want to mess with mercury.
The hoses that come with the gauges are pretty low-grade, so that will be an upgradable item eventually. Other then that, they work great.