Homemade Manometer

cmyoch

cmyoch

XS650 Junkie
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Man o man...o meter! That was the best $2.30 I've ever spent! I made one out of 12 ft of tubing, a yard stick, and some 2 cycle oil. I'm amazed how quick I had them adjusted. Now she runs like striped ass ape. (I've never seen an ape with a striped ass let alone see one running). Anyways, she is running great and I am no longer having high idle issues after running at higher rpm. This bike is acting and running like it's supposed to be. And at 62,000 miles, there should be a lot of life left in her! I wouldn't have been able to do this without the help of my XS family in this forum. Thanks everyone! :thumbsup:

Craig
 
God.. You Guys get stuff for so cheap in the states.. Can't find anything in bulk here. To make that manometer I'd probably spend around $30. Prob can't even find a meter stick for less then $10. The clear tube would come in a bag of a set cut size from Canadian tire at some rediculous price of approx $8 for maybe a foot or two. Etc etc.. Gotta love canada... I think xs650direct is probably the best price for anything, man that guy should sell everything, just become a department store, xs650 parts to washing machines he should have it all
 
All you need is 22 feet of 3/16" ID, 5/16" OD clear plastic tubing. A very small amount of a coloured licquid (Sta-bil or tranny fluid or even water with some food colouring) is also needed. Any old piece of wood will do (metre stick not required, as there is no measuring to be done ).

I bought my tubing from Rona, as they have bulk rolls of all sizes. I think it cost about $7.00 in 2008, so maybe its $10.00 or $11.00 now.
 

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retiredgentleman said:
All you need is 22 feet of 3/16" ID, 5/16" OD clear plastic tubing. A very small amount of a coloured licquid (Sta-bil or tranny fluid or even water with some food colouring) is also needed. Any old piece of wood will do (metre stick not required, as there is no measuring to be done ).

I bought my tubing from Rona, as they have bulk rolls of all sizes. I think it cost about $7.00 in 2008, so maybe its $10.00 or $11.00 now.
Click to expand...

I recently did it with 10' of tubing, $1.79 at crafty beaver, and some two stroke oil, another $1.50. Works way better than the cheap gauges I sold last year. Pretty cool to see the oil levels rise and fall.

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Ya just gotta be pretty close on the synch already before starting up, or the vacuum imbalance will pull the oil out of the tube and into the engine really fast (how do I know?). That's why mercury works so well in manometers - too heavy to be pulled out by engine vacuum; plus it naturally dampens out the "jumping" in the liquid column. Let butterfly plate close on a small diameter drill bit, set idle speed screw so there's just a small drag to pull it out, and set synch screw to get same drag "feel" on other plate. This should get you pretty close on synch; fine-tune it with the oil-filled tube technique; then re-adjust idle speed to spec as needed.
 
I used 2 cycle oil because I figured if a little got sucked in by accident, it wouldn't hurt anything. On my first test, I kept my finger on the kill switch to prevent any from being sucked in.

Apox, the tubing is cheap here in the midwest. I'd be glad to send you 12 or so ft of it. It's light weight so it shouldn't cost too much to ship it. Let me know. You can use an old board or anything to tape it to. I had two yard sticks laying around so I utilized one of them. It has a hole drilled in the top of it so I can hang it on my wall for future use.
 
In my opinion, mercury should be avoided for a manometer for a couple of reasons.

Its a known hazard to a persons health. (designated substance).

As mentioned, its very heavy, which prevents "jumping", but that property actually makes it less sensitive to measuring differential pressure. Since mecury's specific gravity is 13 times more than water or oil, it is 13 times less accurate in a manometer.
 
I agree. Each and every member here has motor oil or something of similar consistancy laying around. I wouldn't even bother with mercury. Let alone risk my health with it. I'm turning into a "Mad Biker" by heart. I don't need for it to actually ring true by messing with mercury.
 
Don't get me wrong - I wasn't suggesting using mercury; just explaining why it was used in manometers historically - like many other materials found to be environmentally undesirable over the last several decades (PCBs for example), it was in widespread use because it has properties that were useful in commerce and industry.

I don't think the fact that it is 13.6 times as heavy as water necessarily makes it that much less accurate in sensing differential pressure - it can't follow very fast pressure changes, of course, but in synching two carbs together, we want to compare relatively steady averages, so try to dampen the pulsations by crimping the tubes, inserting carb jets, etc., essentially accomplishing the same effect as the inertia of a "heavy" mercury column.
 
Some people put very small pilot jets in the hose. The small hole in the jet dampens the fluctuations. XSJohn used aquarium air controls to dampen the flucuations.
Personally the flucuations don't bother me or effect the accuracy or sensitivity any. As it flucuates, one side goes down, the other up. About 5/8 to 3/4 inch or so. Just get it even.
 
There's no need for pilot jets or valves inline with the plastic tubing. Its more accurate without them.

aldo5468;

This is an example of the difference in accuracy between mercury and tranny fluid. Lets say you adjust the sych screw until the mercury columns are within 1/4" of each other. From a few feet away, that looks like they are closely matched. However, if that was tranny fluid, the columns would be 3.3" difference, and you would re-adjust the screw until they were even. The lighter fluid is like an amplifier, making it easier to see the difference.

Yes, mercury can be used...................I had a home built one back in the 1970's.
 
I still use an old original "Carb Stix" with mercury in it and find it very accurate. The mercury is drawn up the 2 to 4 tubes from a common reservoir and they are glass, not plastic. They also have a pretty small I.D., probably something like 1/16". The columns bounce slightly but not much and the slightest adjustment of the sync screw changes them.

My buddy got one of those fancy electronic sync tools, a meter with a needle that swings left or right if your sync is off, centers if it's good. He insisted on checking my 650 carbs even though I told him they were done recently with the Carb Stix and felt good. They were dead nuts right on with his fancy meter. He was impressed and I was glad to have my gut feelings verified.
 
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