Making your own water manometer? This'll help

[CycleRob]

I just had a round of PM's that should not have occurred and you'll see why I think so.

"I'm about to make a 4' manometer like yours to begin syncing the throttle bodies on my bike.
I have various oils including two- and four-stroke engine oils in my garage that I could use for the fluid. Would it make much difference which oil I use? What would you recommend?"

My reply:
I tried oils like ATF, 10w fork oil . . . . even WD-40, but they were either too thick and slow to respond or went rank and got chunky (WD-40). By slow, I mean 15 seconds or more to move and finally stabilize at the new setting. Water is immediately. I use water with about 5% by volume of isopropyl alcohol added to keep it from getting "bacterial" and a couple drops of food coloring so you can see the column. Painting the wood white makes it real easy to see too. It's all "brewed" in a discarded nasal spray bottle (internal aspirator hose/mechanism removed). They're perfect because the tip makes it easy to fill the tube.
My recommendation: make the wood 6' long and get 20' of hose. Mine is 4' with 15' hose. The extra length gives you more range if your synch is a little far out. Also when you start the bike one column always shoots up almost 2'. I guess I need to add a tiny orifice in each hose to tame down the fast response. I'll need to have 2 that are identical though.
The water is VERY sensitive!! I demonstrated it by twirling the 3' end of one hose as fast as I could, showing how centrifugal force acting on the hose's internal air column caused a vacuum that separated the water columns about 5".
EDIT: Doing the same hose twirling test on a TwinMax set to full sensitivity produced no change!

"I had thought to use oil because of the comments I read about the possible oversensitivity of water. Based on your reply, I'll use water. My stick is already cut at 4', but I'll make the hose 20'. Has water ever been sucked out of your gauge into the bike on startup?"

My reply:
No, but it has come real close. Rockster's bike sucked part of the water out when I rolled on the throttle toward 3,500 RPM. Installing matching inline orifices will tame the hyperactivity without decreasing the response time. I'm thinking of using a short length of a spray can pipette hot glued into a removable hose plug.
Getting 20' of hose is a good idea as it'll allow you to use it with a longer wood piece if it's still uncut.

"Not having seen it in action, I'm just guessing here. But, if the balanced columns of water are each about 2' tall, it seems that a 4' stick with 20' of hose should work as well as a 6' or longer stick."

My reply:
You fill the hoses to just over ½ the wood stick's length. That's where the longer stick gives you more of a siphon negative pressure diff capability. You do it just over ½ full at rest so it doesn't suck in air at the bottom when the top column is about to top over and go down. If it sucks air the siphon vacuum goes away immediately and the water column shoots out fast.
We should have done this all as a post. I'll copy-n-paste the text without saying who it is for the group benefit. Please stay anonymous and next time do this in a post so the group benefits. I cannot be everyone's personal mechanic when it is not only not justified, but shortchanges our fellow riders.

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[Ritchard]

My reply:
No, but it has come real close. Rockster's bike sucked part of the water out when I rolled on the throttle toward 3,500 RPM. Installing matching inline orifices will tame the hyperactivity without decreasing the response time. I'm thinking of using a short length of a spray can pipette hot glued into a removable hose plug.
Getting 20' of hose is a good idea as it'll allow you to use it with a longer wood piece if it's still uncut.


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I made a 5 foot stick on a piece of white 1x6 doorjam from the lumber store, with groovy red food-coloured water inside. It was a quick and gratifying project to do. One error I made was using 1/4" inner diameter tubing. I am sure I read that somewhere, but it is too large, you have to hold the tubing firmly in place. My son did not care for holding the other side as long as it took to fiddle with the thing.

I did have a problem where the water could be sucked very rapidly out of the 25 ft of hose if you made the slightest error with the above. Can you elaborate on your idea of installing an orifice? Where would you put it, and what you would expect it would do?

Thanks,

R

[zeke]

I am taking the plunge this weekend and gonna make one of these bad boys. What is the correct internal tube diameter? I don't want to buy 20 ft of the wrong size !
Educate me if I am wrong but I just stand this up next to the bike, hook it up like I would a twinmax or other device, and just watch the water. How much water do I need? How much should the water move less than 1".... 1/8"... ? Will it just kind of appear still when the tb are balanced? Thanks and I'll keep you posted my weekend project!

[CycleRob]

The volume of water needed isn't much. I made mine in a discarded nasal spray bottle modified to just squirt and had about ½ bottle to spare. Bottle pics to follow with the new orifices. The orifices should go at the ends that plug on to the TBs. That way the entire downstream air column leading to the water columns serves as a pulsation damper chamber.

To make a pair of orifices Something like 1" (25mm) sections of spray can plastic pipettes wrapped in several turns of electrical tape so that it will fit tightly inside the pipe. Forcing it in there without damaging the orifice openings will be the challenge. Maybe another larger pipe that just fits over the pipette and just inside the manometer hose.

I'm logging off until late tonite, getting on this orifice creation and the rest of my chores, now.

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[boxermania]

Robbie

I made a comment regarding the WM in the Gainesville Tech Session post. The WM is more sensitive than the TwinMax considering that on the TM at Max sensitivity one has to make a judgment call based on the rapid swing of the needle.

The WM does have two minor issues that as you indicate can be easily updated. From my perspective, close observation and actual use of the device here are the issues and potential solutions:

Water ingested by the running engine due to large imbalance of the TB’s or by raising the engine speed during the adjustment.
Although not a problem with the TM, it does become an occasional annoyance with the WM due to its increase sensitivity. Rest assured that the amount of water that can potentially be ingested has such a small volume that it will vaporize as soon as it’s exposed to the combustion chamber latent heat.

Solution
Install a “snubber or pulse damper” in the lines. This will not affect the resolution but will slow the response slightly as the pressures on either side of the damper have to equalize, personally I don’t think it will be noticeable but will have to test to validate.

Orifice size to eliminate the sucking of the water
I would start with a 1/16 hole (.0625”) and probably work myself down to something in the order of .040” which is typical of the alcohol/water injection kits for automobile application. Remember the intent here is to not suck the water out on a poor balanced TB’s or when raising the rpm’s to 3500 to check the TB balance.

Solution
I would consider an insert slightly larger than the ID of the rubber tubing (please note that the inserts have to be the same length) installed close to the top of the stick and before the lines leave the stick.

What should be the column height differential in the WM to be considered a successful balance
Since the WM is more accurate than the TM a differential of 1” in the column heights is, in my estimation, a dead on adjustment as trying to improve on this necessitates a myriad of minor adjustments and not worth pursuing.

Water column separating and leaving small water droplets attached to the ID of the tubing
This is something that will be more of an annoyance than a detriment to the WM performance (based on the height difference of the WM columns on a bike previously balanced with a TM, I would say that the WM has at least an order of magnitude better resolution than the TM) and it is due to the surface tension of the water and the ability to "cling" to the ID of the tubing. The addition of the rubbing alcohol, I guess with the idea to improve the “lubricity” of the water column, albeit a good idea I believe that eventually the alcohol will evaporate as the ends are open and exposed to the atmosphere.

[kantuckid]

I bought a Twinmax on the web used for $75 and just got back from a test ride-it really doesn't run any better than it did but it goes like it should! My idle is @ 1000 and I just left it there. A problem I have had recur several times is that, having removed the carbon cannister and related parts some time back, I find that typical rubber vacuum caps only last for a few months and then are badly cracked.They make a neat cover but they must not stand up to the heat in that area as I have replaced them 3 times since the surgery.At first I thought maybe they were just Chinese junk . I thought I'd mention this concern as many do the removal and I have replaced them with tubing and a small machine screw stuck in the tubing. Hope this does the trick and likely it will as that's what was there to begin with.

[CycleRob]

I tried the tape wrapped spray can pipe orifices, tightly installed, and they screwed up the accuracy. It showed 1¼" error right side high at idle that changed to 1¼" error left side high when I swapped the hoses to the other cylinder. The very tiny hole in that spraycan pipe gave a slowdown from the normal jittery response and fast movement that was perfect. Removing both orifices got the readings back to even again. That was with the orifices pushed into the hose ends right at the TB spigots. Installing another set of orifices with better precision at the top of the WM has the best chance of success, seeing as how the original plan A failed.

I am reluctant to cut those hoses at the top to add those orifices, ideally a set of carburetor pilot jets from a 600cc four. They would even be the right interference fit size to stuff inside the tubing. Until then, my advice is to make your WM at least 5 feet tall with 18 feet of 1/8th inch tubing or 6 feet tall with 20 feet of tubing.

[harveyrawn]

I have just completed a WM that is about 42" tall with 24' of tubing that I hang from my handlebar mirror. When I place the bike under the overhead garage door, I can drape the tubes over the steel rod at the edge of the door and the tubes will reach the throttle bodies. That gives me about 6' tall tube columns to accommodate about 48" of water columns in the WM.

I plan to try its maiden voyage tomorrow. I'll post my results.

[harveyrawn]

That gives me about 6' tall tube columns to accommodate about 48" of water columns in the WM.

That was a typo. The balanced water columns are 38" tall, just below the top of the WM. If they balance with about 1" of differential height, I think the device should work OK.

[CycleRob]

harveyrawn,

To set the optimal water level, measure from the lowest loop of the bend at the bottom -to- the hoses where they crest the top and add 2 inches to that. The 2" adds on enough so that when the water column is about to go over the very top, the other water column has about 2" BEFORE it will pass thru the bottom loop and suck in air, effectively breaking the siphon. When the lower water column passes thru the bottom loop and sucks in air the water column gets sucked out fast!! That's to be avoided!

One more real important thing . . . the tube lengths must be exactly equal. That means the exact bottom of the water loop has to be the exact middle of the total tube length. Otherwise the unequal air chambers will react differently to the small vacuum pulsations, showing a synch error when there is none.

OK. So, to fill the tube correctly the first time, that top-2-bottom dimension + 2" is the length of water column you need. Put one hose end in the bottle of dyed water (+10% by volume Isopropyl for sterility) and draw a vacuum in the other end until the column gets to that dimension you marked on the tube with a paper clip. Make it easy on yourself and have less drama if the WM stick is nearly horizontal, like a 12 minutes after the hour (analog) angle. If you mess up, and you will, it's not that hard to fix by using the little squirt bottle to add or subtract the water to make it right. You'll have to play with it gently to get all the water sections together as one. Ideally, when you raise the left column slowly with mouth suction almost to it's top-over point, the right column should be at the 3 O'Clock position on the bottom circular loop.

That was easy.
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[harveyrawn]

Rob,

Thanks for the direction. That's more or less what I did today, but I'll re-check the water vs. tube height tomorrow before running the test. I was adding and subtracting water with the WM vertical and had a battle getting the amounts right and all of the water joined up in the tubes, especially when I had the tubes at their full 6' height. The increased difficulty in moving the water at that height by sucking or blowing gives me hope that I won't experience a siphon-breaking event in actual use.

Next time I'll try establishing the water level with the WM and tubes closer to horizontal during filling.

[harveyrawn]

Rob,

When you said the water manometer was sensitive, I think you meant SENSITIVE. I sucked the water out of mine twice today while learning to make very small changes and adjustments. I ultimately synced the throttle bodies at 1,100 rpm idle and 4,000 running.

Before doing that procedure, I readjusted the valves with the spark plugs installed per your recommendation. One intake and one exhaust valve were a little too tight.

I found a noticeable difference in the bike's behavior after doing those procedures. It seems to respond to the throttle quicker and more smoothly than before. It seemed like a different bike pulling out of turns.

Thanks again for your guidance. It makes owning a fun bike even funner.

[CycleRob]

Yes, SENSITIVE. That's why I said to make your WM stick at least 5' tall, 6' tall even better. It is so cheap to make you can splurge and go for the 6 footer.

What really helps is if/when you understand the correlation between throttle/BBAS opening and water column height. The smaller BBAS/throttle opening has the higher intake vacuum and the higher water column. Conversely, the larger BBAS/throttle opening has the lower intake vacuum and the lower water column. So it's smaller=higher, larger=lower. Knowing that, you don't have to experiment with which way to turn either the BBAS or throttle cable adjuster. You already know which way, and with experience you'll learn the "how much" fairly quickly.

Setting the idle speed to 1150 from the current 1000 RPM when the left water column is high, you know you first have to turn the left BBAS in the loosen (CCW) direction until either the columns become equal or the RPM is at 1150. Then alternately micro adjust both BBAS from there until the RPM's right. Takes 1 minute tops.

Before you do the 3,000 RPM synch setting, you first need to check for minimal freeplay at the twistgrip's cable freeplay adjuster. Then check the left TB's throttle cable freeplay. I do that by deflecting the exposed short steel inner cable section with my finger midspan where it connects to the throttle shaft pulley. It should have minimal wiggle deflection freeplay, NOT be loose enough to deflect in an arc over ¼" (6mm) from straight. When there is too much freeplay like that your fast idle will be too slow, even if the fast idle cable has near zero freeplay. If there is too much left TB cable freeplay AND the "on throttle" 3K RPM synch was OK, you need to raise both cables in small EQUAL amounts until the left TB cable freeplay is minimal. By minimal, I mean a looseness that allows the cable to deflect from straight about 1/8th " (3mm). You have to do them in equal amounts so you do not suck the water out of one hose from the excessive synch error. Just be cautious when you roll on the throttle and watch which column goes high. That's the one you need to raise (unscrew) the cable adjuster on so it'll even up with the other side. Go slow with no more than ¼ turn adjuster changes each time until the left side exposed inner cable center slack is at 1/8th" (6mm). Now turn the handlebars full left/right steering stops at idle. There should be no idle speed change. If there is an idle RPM increase, give more throttle cable freeplay up at the throttle cable adjuster on the handlebar and try it again. Man, I sure hope you had that 20" BoxFan aimed at the engine all this time because we just generated a LOT of heat!!

So now you know what to use, how to use it and you can make the correct adjustment, the right way, the right amount, every time. Once you get the experience making the adjustments the water columns are telling you to make, everything I just described above can be completed in under 5 minutes. The key to it all is understanding what the higher or lower water column is telling you. If you just start turning things you waste too much time and you can REALLY screw things up! It's so much quicker with the right moves. Compare it to driving a car. Left turn approaches, you know the steering wheel will have to be turned left. You even know about how much to turn it. Imagine someone else "driving" but to take that left turn he's getting ready to turn the heater fan knob TO THE RIGHT instead!!!

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[harveyrawn]

What really helps is if/when you understand the correlation between throttle/BBAS opening and water column height. The smaller BBAS/throttle opening has the higher intake vacuum and the higher water column. Conversely, the larger BBAS/throttle opening has the lower intake vacuum and the lower water column. So it's smaller=higher, larger=lower. Knowing that, you don't have to experiment with which way to turn either the BBAS or throttle cable adjuster. You already know which way, and with experience you'll learn the "how much" fairly quickly.

Although I achieved equal water column heights at 1100 and 4000 rpms, advancing the throttle, slowly, from the lower to the higher setting caused first one column to be higher, then the other one. It's apparent that both sides don't operate in perfect sync throughout the rpm range. Do the relative BBAS settings continue to affect the behavior of the water columns at higher rpms?

[CycleRob]

Very slightly if at all, but you're supposed to set the idle synch with the BBAS first, making that question irrelevant. The cable synch doesn't come into play until both cables rotate and lift both throttles off the mechanical idle stops.

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[harveyrawn]

Very slightly if at all, but you're supposed to set the idle synch with the BBAS first, making that question irrelevant. The cable synch doesn't come into play until both cables rotate and lift both throttles off the mechanical idle stops.

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Ergo, one wants both cables relaxed at idle so that they are not affecting the idle sync, right? Presumably, they will then pull evenly when the throttle is opened.

[Ritchard]

I remade my stick over the weekend with .017 inner diameter tubing. That made the job of synching the throttle bodies totally easy. Well at least at idle. I cannot believe how touchy the cable adjustment is. Is there any trick I do not see for getting the cable adjuster tightened without affecting the 3-4K RPM synch?

[boxermania]

Ritchard

Too much sensitivity is as bad as too little sensitivity. During the Tech session at Robbie's I noticed that synchronizing with the TwinMax and then going to the WM there was approximately a ten fold (the height of one column was approximately ten times the height of the sister column).

That being said, if you can get the columns on the WM within an inch or two differential you would be in essence dead on. The important thing to keep the engine at 3500 to 4000 rpm as that is the typical operational range of the bike.

Hope this helps

[Ritchard]

I guess it's close enough then; at idle on a 5 ft stick, I have both of the columns absolutely dead even. At speed, they're around 1-1/2" diff. I can get them perfect, but tightening up the locknut invariably threw them off a little. It was just bugging me, as I was trying to be so careful.

Thanks again everyone for the collective wisdom here.

R

[CycleRob]

Ritchard,

A 1½" error is almost close enough on the WM, but to have almost no error after gently tightening the locknut on the cable adjuster you adjust it so it's water column is an inch higher. Then, when you gently tighten the locknut it will pull the adjuster from resting on the bottom of thread engagement to the top of thread engagement (the play in the threads). That should get it near perfect. It's that thread play that is taken from above the male threads and moved to below the male threads that screws up your perfect adjustment. In a word; Compensate.

Time to repeat the warning again. You know, the one about being very careful you do not overtighten the locknut on the easily broken powder metal cable adjuster. It only has to be tight enough so that it will not loosen up. Too loose and it loosens up = no big deal. You do the synch again and it's over. Too tight and it breaks at your own hand = really bad thing. If you break that adjuster, you'll have the $26 replacement cost of that side's cable assembly -and- the worst part; a minimum of a hour's labor to replace that cable. Too much has to come apart just to get at the throttle junction box assembly, then it has to go back together and be synchronized. Having voluntarily performed those disassembly steps as a check-n-see photo archive addition to my clutch spline greasing service, I know all to well what a PainInTheAss it is. Threat that adjuster like it's made out of a very, very strong plastic.

You have been warned.

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