Building your own carb sync tool--source for gauges

how small of an opening do they install for this? I've got gauges and I want to make a nice manometer, but whenever I hook 'em up to the carbs, the needles jump around everywhere.. I don't think I have a dampener in there - the opening is around 1mm I think.

Thanks!

I have heard (I think it was TwoCam on this site a number of years ago) that you can use the air valves from an aquarium setup to dampen out the fluctuations. They have banks of single, two, four, etc. of the valves. Now that said they are probably more expensive than the 75 cent this seller is charging for the inserts. But it's an option.

Bill

They are actually just restrictors. They are just a tiny plastic plug stuck into the hose about 1 inch in from where the tube connects to the engine. The opening is a pinhole. 1mm would be too big. The tubing, along with the restrictor creates a dampener. The volume of air in the tubing acts to smooth out the pulses and the restrictor limits the air flow.

Therefore, in order to get the same readings, each tube must have the same air volume and the same restriction. But tubing never reacts the same so you need to calibrate the rig after it's assembled.

Note: the manometer is then only calibrated and accurate for near the RPM used during the calibration. In other words calibrate it at idle, and only trust the reading at idle. At higher RPMs, like when you blip the throttle, the reading may no longer be accurate.

Here's how you do the calibration on a mercury manometer. The same technique can be used to calibrate the gauge-type, but I can't say what size the restrictor should be for the gauges. Start at pinhole and work your way bigger.


Post edited by: loudhvx, at: 2007/08/09 11:07

And since I'm in a posting mode...
Sometimes, air bubbles will show up in the mercury sticks.

The air bubbles throw off the reading so they need to be removed. You can remove them easily while the engine is running with a cheap plastic syringe from a pharmacy.

It should not draw up any mercury. If it does, the mercury level may be too high in the reservoir.



Post edited by: loudhvx, at: 2007/08/09 11:13

pyxen wrote:

how small of an opening do they install for this? I've got gauges and I want to make a nice manometer, but whenever I hook 'em up to the carbs, the needles jump around everywhere.. I don't think I have a dampener in there - the opening is around 1mm I think.

Thanks!

The orifices in the plugs that they put in the gauges I bought were VERY tiny. Only big enough to insert a very fine wire.

bump

I HATE to bump such an old thread, but this looks like an awesome idea. When I look on the link to the store (which is still a good link oddly enough) I'm not sure which gauge to pick as most of them look like they do pressure, not vacuum. Also, by "dampeners" does the OP just mean the fittings that attach to the gauge? Any one else do this?
Thanks again and sorry for the dead post bump.
Tom

The idea of the dampers is to prevent the needles on the gauges from jumping. If you just use a hose from the carb to the gauge each intake pulse will make the needle on the gauge jump up then immediately drop back to 0 at the end of the pulse. The result is the needle keeps bouncing back and forth so wildly that the reading is not useable. The damper installed on the hose near the gauge tightens down the inside diameter of the hose and dampens or stops the needle fluctuation. Ed

In addition to that dampener, there should also be one as close to the intake tract as possible. By being close to the engine, it prevents the hose and gauge from altering the vacuum in the manifold.

And if you have one close to the engine, it can do both jobs of isolating and dampening such that you won't need a second one near the gauge.

home.comcast.net/~loudgpz/GPZweb/Manomet.../ManometerNotes.html

HEllo all,

I have a repeat question... which of the gauges should I buy from the website. The link posted previously is now expired and I would love to take advantage of the knowledge in this forum....

I just want to know what model number gauge you guys reccomend.

No eBay APP ID and/or Cert ID defined in Kunena configurationHere is the absolute best set you can buy. They are new and they are what the Kawasaki pros at dealerships (wealthy, successful dealerships that is) used on our beloved KZ's. Just warm up the checkbook before looking at the price:

mercury is better