Question about homemade mechanical carb sync tool

I have an idea for a homemade carb sync tool. No, not the thing with the clear tubing and the 3 foot long ruler and transmission fluid.
At a place here in Toronto called Princess Auto, I saw mechanical vacuum gauges with readings on the dial that go down to -75 Hg. They cost $5.99 each. For $6.99 they have gauges with readings down to -100 Hg.
Princess Auto also has brass hose adapters that fits on the end of the gauge for $1.99 each. You can push a clear or black plastic tube onto the adapter.
That would be about $35. including tax, instead of the $109. plus tax I've seen sync tools advertised for.

So would it be possible to mount 4 of these gauges with adapters on a sheet metal or wood backing, run hoses off them and use it as a carb synch tool?
Is there anything else about the commerical carb sync tools that needs to be included?
Also, in the official Yamaha Service Manual they show a Carb Synch tool that uses 1 gauge and has 4 hoses coming off the bottom from an adapter. There's also a switch that allows you to switch from one carb to the other. I guess you did each carb individually back then instead of all 4 at once.
Any input much appreciated.
thx,
baz

 

Very possible - You need to add restrictors of some kind. Either fishtank air valves or drip irrigation valves work well.

The one in the book just let you switch to each cylinder and test like Ricks method has you do.

 

So when you say restrictors like fish tank air valves, where would they go - between the gauge and the brass hose adapters?
advice much appreciated,
baz

 

Just in line between the carb and the gauge - without restriction they needles bounce like crazy because the vacuum pulses. So you will need 4 valves.

I use a single gauge set up - I need to get some cheap gauges like those and make a 4 gauge set up.

 

I haven't seen these, but my thoughts are that if you put 4 exactly side by side and ran them off your car, you will find that they "level out" at different levels, because they are not precision engineered.

Then the obvious solution is to attach them to the board at slightly different levels so that they will read "level" when hooked to a common vacuum source.

You would be calibrating them when you make the tool. I like it.

 

I'm not sure I understand. When you say attach the gauges to a board at slightly different levels so they will read 'level', how far apart would they have to be? Or would I have to experiment with different positions with the four gauges hooked up to the bike? And so I would know they're calibrated if the gauges read around the same? Is that the idea - or am I way off base?

 

Also, Bill, I meant to ask you - when you say you use a single gauge set up. Do you just switch it from carb to carb and make your adjustments so it reads the same? That seems pretty simple and easy too. And depending on the price of a fish tank valve would be pretty darn cheap to make.

 

Yes exactly - take a look at this - Rick's method - One gauge - one valve a few golf tees and some hose.

Carb Sync
http://www.xjbikes.com/Forums/viewtopic/t=2132.html

Only thing is it would be nice to have 4 gauges - a bit quicker to do a sync

 

Time these are dial gauges so I'm not sure about height, but you make a good point about calibration. Most can be set so I suppose you could run all 4 on one cylinder with the same restrictor and calibrate

 

I thought Baz666 found something like a Carbtune for $6.00 each.
Scratch what I said, buy one gauge and a fish tank 4 valve thing and make an inline restrictor. All in you're at $10.00

 

Yeah, I guess that's the idea X 4. Which would be $24 Canadian for the vacuum gauges, about 1 dollar for the tubing and the fish tank valves I found are $2 each. Or you could make the valves with the little plastic spray can straws like Rick O Matic talks about.
So, with tax, it would come out to something like $30 or $32 for a 4 gauge carb sync kit. But I supposed the single gauge is fine. I'm assuming you just switch from carb to carb and set up the same amount of vacuum - right?
thx,
baz

 

your only going to be reading about 10, most testers go to 30 at 75 max your not going to get real fine readings, but it will work
a aquarium store will have 4 gang air line valves, with individual shut off's
so you only need 1 valve 1 restrictor 1 gauge and 5 hoses