Pressure gauge for balancing

[Guest Nigelstephens]

Does anyone know of a differential pressure gauge that is not too expensive for balancing a Guzzi?

Digital or otherwise.

 

Thanks

Nigel

[Guest ratchethack]

Nige, if y'er seriously interested in "not too expensive", the one I've used many times for "perfect" TB balance cost a few dollars USD. It's ye olde home-built water manometre, made of 10 ft. of 5/16" O.D. and 10 ft. of 7/16" O.D. clear vinyl tubing from the local hardware store, zip-tied to a length of schedule 40 plastic pipe as a support, which can be hung up next to the bike for doing the balancing. The 5/16" O.D. fits the intake barbs and seals up well shoved into the 7/16" O.D., which has much less sensitivity for reading -- about right, I reckon. Works like a Champ.

[callison]

Expense is relative. Once you've paid the tab for a mercury spill when you've upset your CarbStix, a Twin Max will seem like a really good idea. There's nothing wrong with the water manometer either except that you can't stick it in your tank bag and take it with you.

[richard100t]

Expense is relative. Once you've paid the tab for a mercury spill when you've upset your CarbStix, a Twin Max will seem like a really good idea. There's nothing wrong with the water manometer either except that you can't stick it in your tank bag and take it with you.

I agree with Carl about the Twinmax. It works well, & you can find it on the internet for under $100.

[Tom M]

Here's a home made solution:

 

http://www.advrider.com/forums/showthread....ight=fork%2Boil

[badmotogoozer]

ditto on the Twinmax! No fuss, no muss, not terribly expensive. Excellent value for $100.

 

But if "no money down, do not pay until 2010" is your game, then go with the water mano. Avoid the mercury. The spill risk just isn't worth it.

 

 

Rj

[Murray]

Athough I have never got off my rear and actully done it I should probally do it before they become hard to find but the stupid power/econmy gauges that manufactures used to fit to cars mainly in the mid to late 80's when they couldn't be arsed fitting something actually useful like a tacho are vacum gauges. Get two of them Local wreckers mumbled something about 5 bucks each prefably from the same model/make and a bit of plumbing the air tube and taps for an aquarium jumps to mind and your're pretty well there. To calibrate hook them both up to one cylinder and simply pop the needle off and repostion it so they both read the same. As its a difference we are intrested in rather than the actual reading. No water mecury and vaguly portable. Some ducati shops were int he habbit of buying a set of four for a big japper cutting them in half and selling them for half the price of four.

[Alex-Corsa]

Does anyone know of a differential pressure gauge that is not too expensive for balancing a Guzzi?

Digital or otherwise.

 

Thanks

Nigel

 

I suggest one of these, http://www.carbtune.com/ Thez ain't expencve and work great.

[Ballacraine]

Twinmax!!

 

Nige.

[mike wilson]

I'm with Ratchet. If you have a screaming urge to be hyper-accurate, give me a shout and I'll "loan" you a metre rule from work to stick in the middle of the U so that you can get it millimetre perfect.

[Guest Nigelstephens]

umm been thinking. Would a digital displayed unit be of interest that you can attach to the bike?

I used to use diffential gauges based on a wheatstone bridge in a job a few years ago. I think they're quite cheap and accurate once calibrated.

Not sure if it would be of any use when crusing other than something tech to show off so perhaps not. After all its only at small throttle openings that balance matters much.

[waspp]

I have wondered the same thing, I don't see why they wouldn't work and be easier than other methods. I have looked at them on ebay and am tempted to try one, but not sure about who makes a good reliable instrument.

[mike wilson]

umm been thinking. Would a digital displayed unit be of interest that you can attach to the bike?

I used to use diffential gauges based on a wheatstone bridge in a job a few years ago. I think they're quite cheap and accurate once calibrated.

Not sure if it would be of any use when crusing other than something tech to show off so perhaps not. After all its only at small throttle openings that balance matters much.

 

What would you use as a sensor? Heated wire?

 

I entirely disagree with your last statement. Why do you think so?

[Guest Nigelstephens]

I'm interested in your reaction. Please tell me more?

I was thinking that balancing is more critical at low throttle openings. Once it is set there it will be okay for larger throttle openings. If you think in terms or the amount of air passing the butterfly/slide at small openings a minor adjustment will have a big affect on static pressure. At half open throttle the pressure difference between the two sides is likely to be quite similar, especially as the pressure in the manifold will have reduced. So set it at near idle for the whole range as more accurate.

 

I have been thinking about this alot recently. I have a project in mind to produce a digital differential meter that displays in an LCD a simple indication which side is out of balance "-----|-*---" meaning right side is sucking more (thanks to Cliff Jefferies and the MY16M display for mixture correction).

In addition have the pressure in the second line of the display showing pressure in PSI, mmHG or kPa. + or - meaning left or right biased.

I was thinking in terms of an instrument one would attach for tunning. However, it could be a permanant addition to the bike and display the balance when riding (even though it would show in balance nearly always) but at traffic lights it would show exactly what you needed to know.

 

I already have a pietzo wheatstone bridge differntial sensor (+/- 5PSI) (£10 RS components) in my possesion to do some tests on. The difficulty is the microprocessor and program to interpret the signal and to display in the LCD. I have programmed PIC controllers in other projects and this is just the thing for this. I think it could be done for under $100.

[mike wilson]

Where to begin? Depending on your machine, it is entirely possible to have perfect balance at tickover, yet wildly imbalanced carbs once the throttles are opened. The mechanisms for setup are often entirely different. The perception of balance can be most obvious at tickover, because the engine is running so slowly and due to the particular Guzzi configuration but, just because humans don't notice it so much, it doesn't mean that unbalanced forces are not having major effects at other times. I am having to examine your thought that the pressure differential has a decreasing effect at increasing throttle openings. Will get back to you on that.

 

WRT your constant monitor, I think the main problems will be in two areas. Firstly, the sensor. There are various types that either measure pressure directly or can be modified to give you a reading. As an example of the second, you could use a hot wire air flow sensor to give you a reading that can be measured against one in the other manifold to give you an idea of "balance". A bigger problem will come with the Guzzi engine configuration. The large, slow and irregularly spaced pulses (especially at tickover) of the Guzzi engine will almost certainly cause problems with factors like resonance of the sensors. That is why I thought you might be using an indirect measure of manifold pressure, like an airflow sensor, which can be more easily and accurately damped.

 

None of the above is intended to put you off. I think the idea is excellent but it may take more effort to make work than you originally anticipated.