Carb synching question, again....

[KrazyKarl02]

Thanks for the help to those who commented on where to find the individual vacuum ports on my 81 GS 1000, now for my next question. Where is the best place to get the adapters so that my synch gauge tubes will screw into my head? Previous synchings I had done before the vacuum ports were on the carbs and just plugged in.

I notice JC whitney sells one for the FZR, are these the same adapters I need??

Thanks

[Anonymous]

I have a set of vacume guages from JC whitney and they CAME WITH 4 brass tubs with tiny holes in them--You use an allen wrench to remove the plugs from each carb and then these 4 items screw in place of the plugs--they came with the vacume guages--If the items that JC whitney are selling are billed as replacements for the ones that come with the vacume guages then my guess is that they are what you want--BTW each vacume line has a small plastic valve like the ones used in fish tank air supplys that dampens the vacume so the pulses are not showing up on the guages --If you need any more information from me than i will be glad to dig out the set of guages and measure things for you.(((I HOPE ALL THIS WAS OF SOME HELP TO YOU))

[SqDancerLynn1]

fzr adapters are offered in addition to what comes with the gauges so i don't think they are what you want, try to make your own Use heavy wall
brass tubing large enough to thread the end to fit the intake hole

[first timer]

does the length of the brass adapters matter i need to cut one shorter (#2 carb ) to get it to fit, do i need to to cut the brass adapter on the #3 carb to get a equal reading

[Anonymous]

No they can be different lengths. The sync gauge I used had two longer (4") tubes for the two inner cylinders and two shorter (3") tubes for the outer cylinders.

[silverhorse47]

...BTW each vacume line has a small plastic valve like the ones used in fish tank air supplys that dampens the vacume so the pulses are not showing up on the guages... --SCOTTY

Scotty, can you tell me more about these plastic valves and what they do? I'm rigging up a vacuum guage and it sounds like I need these...

Thank-you.

[Anonymous]

...BTW each vacume line has a small plastic valve like the ones used in fish tank air supplys that dampens the vacume so the pulses are not showing up on the guages... --SCOTTY

Scotty, can you tell me more about these plastic valves and what they do? I'm rigging up a vacuum guage and it sounds like I need these...

Thank-you.

First of all dont forget what 5 string said-- the length is for convenience to the tuner if you want them-
the little valves are necessary as far as i see--without them the guages will be jumping up and down and dificult to get accuracy. by closing each individual valve slowly , you can dampen out the pulsing and actually read the vacume

[silverhorse47]

So the valves are just closing off the bore of the hose? like turning off a tap a little bit at a time?

[Anonymous]

So the valves are just closing off the bore of the hose? like turning off a tap a little bit at a time?

I BELIEVE THAT COVERS IT

[mcconnell]

I have a set of manometers without the dampers and at ~1750 rpm, Suzuki's recommended carb synch point, the mercury does not bounce. The mercury does slowly rise and sink, but it rises and sinks in all the tubes at the same rate, so it does not affect sychronization between the cylinders.

[Anonymous]

I have a set of manometers without the dampers and at ~1750 rpm, Suzuki's recommended carb synch point, the mercury does not bounce. The mercury does slowly rise and sink, but it rises and sinks in all the tubes at the same rate, so it does not affect sychronization between the cylinders.

the mercury ones are definitely better than my vacume guage types

[Anonymous]

I have a set of those JC Whintney vacuum gauges but even with the little valves they bounced around alot. I replaced the gauges with ones that are damped with glycern. Those worked much better. The mercury carb sticks are much better. That is what the factory uses. A note of caution though, If you so much as blip the throttle with the mercury carb sticks, the mercury will get sucked into the engine. It does not hurt the engine, but the carb sticks will be useless.
Al

[silverhorse47]

My vacuum guages bounce around regardless of what I do to the hose.
Al, how do the glycern doomahickeys on your guages work? And what kind of guages did you buy to replace the JCWhitney ones?

[earlfor]

Not a problem, you can order replacement mercury vials to refill your guage. Last time I checked they were only about 6 or 7 bucks.

Earl

. A note of caution though, If you so much as blip the throttle with the mercury carb sticks, the mercury will get sucked into the engine. It does not hurt the engine, but the carb sticks will be useless.
Al

[Anonymous]

There are a few ways to do all of this and they all do about the same thing. You can make a manometer using oil as long as the tubes are long enough. The weight of oil is much less than mercury and so the scale is about umpteen to one to that of mercury.

Mercury is self dampening, that's why it is so good and doesn't require fish-tank valves in the line.

Vacuum is easy to read in an 8 cylinder engine, but on a motorcycle you read one cylinder at a time and that flucuates a great deal. The fish-tank valves (or any fine metering valve) will suffice to dampen the readings. You should (and this may be what Scotty has) have orfices in the intake manifold port plugs that are very small; say, the smallest drill bit you can find. I plan to make my own by drilling out the center of the appropriate size headless screws on the lathe leaving just about 1/8" of meat to drill this small hole. This will also have a dampening effect.

Vacuum gauges are OK, but I wouldn't recomemnd them for any fine tuning because getting steady readings on needle gauges, and getting four gauges that are the same, and/or trying to do one cylinder at a time is pretty tough.

You can buy a carb stik (mercury manometer) with four 2 foot long glass tubes (to minimize the risk of sucking mercury into the cylinders) and mercury to go with it for about $40 USD from your local bike shop or JC Whitney.

Cheers,

Roger