Author Topic: Ok. Here’s another one..  (Read 460 times)

Online Huzo

  • Guzzi Hero
  • *****
  • *
  • *
  • *
  • Posts: 6545
  • Location: Creswick Australia
Ok. Here’s another one..
« on: March 18, 2019, 10:00:28 PM »
On the topic of flow benches..
There’ve been various incarnations of home grown ideas regarding flow bench construction for re setting of rooted TB’s due to unwarranted manipulation of SS’s.
How ‘bout this..
Get a known good set and put them on the workbench.
Attach the standard air box and intakes to the TB set up and eliminate extraneous leaks.
Block off the snorkel.
Fit a spigot to the air box and plumb it to a (small) compressor.
Fit an air bleed in the plumbing between the air box and compressor.
Fit a spigot to each intake and attach a U tube manometer to each spigot.
Arrange the hoses into a U tube manometer setup.
Fill both manometers with a suitably dense fluid, (remember it’s DENSITY not VISCOSITY that is the focus of our attention), also bear in mind that the air bleed on the compressor side can be adjusted to “waste” pressure in the system so as not to pump the fluid out of the U tubes.
Level the fluid in the tubes.

Start the compressor with the outlet open to provide a manifolded flow through the TB’s with appropriate manipulation of the bleed to prevent pumping of the fluid.
Bear in mind that any slight fluctuations in compressor output, will not be of consequence because the supply is manifolded.
Now the reading you see on the U tubes will be that which is produced from a factory set of un molested TB’s.
The actual flow rate is not quantified, but it will give a reading on the manometer, knowing the value in litres/minute is immaterial, you just know it’s factory correct...
Mark this reading on the tubes.

Disconnect the good TB’s from the rig and attach the rooted ones.
Close the airbleeds.
If you have not farted around with the air bleed from the compressor, the flow will be the same as the test with the factory good TB’s and you could open or close the butterflies and manipulate the SS and the bell crank to re-produce the readings on the U tube, that you got with the un molested ones..

I think...!
« Last Edit: March 19, 2019, 05:10:05 AM by Huzo »

Offline Rick4003

  • Guzzi Mentor
  • ****
  • Posts: 422
  • Location: Denmark
Re: Ok. Here’s another one..
« Reply #1 on: March 18, 2019, 10:07:31 PM »
Interesting idea, give it a shot and let us know if it works! :grin:
Moto Guzzi 850 T5 (850 sport) - 1985
Moto Guzzi Ambassador - 1967
Yamaha FZR 600 - 1996

Online Huzo

  • Guzzi Hero
  • *****
  • *
  • *
  • *
  • Posts: 6545
  • Location: Creswick Australia
Re: Ok. Here’s another one..
« Reply #2 on: March 18, 2019, 10:10:32 PM »
Mine are known to be 98% good after having their guts Roperised, but if I knew mine were shagged due to SS interference, I’d be all over it like a cheap suit..
I’m figuring that once you raise the butterflies off idle by packing the throttle stop open a bit to achieve what corresponds to 3,000 rpm, any discrepancy in flow rate between the two will show as an increased pressure in the venturi on the air box side, due to reduced venting (flow), and the right can be brought back to the left by manipulation of the bell crank.
Then drop the butterflies to idle position, ensuring the pressure reading on the left one is is equal to the factory (good) one, and then manipulate the appropriate air bleed to achieve balance in pressure and therefore equal flow.
« Last Edit: March 19, 2019, 10:06:32 AM by Huzo »

Online Kiwi_Roy

  • Guzzi Hero
  • *****
  • *
  • Posts: 7192
Re: Ok. Here’s another one..
« Reply #3 on: March 20, 2019, 03:08:51 PM »
............ I’m figuring that once you raise the butterflies off idle by packing the throttle stop open a bit to achieve what corresponds to 3,000 rpm, any discrepancy in flow rate between the two will show as an increased pressure in the venturi on the air box side, due to reduced venting (flow), and the right can be brought back to the left by manipulation of the bell crank.............. .........
 
Exactly , as you know only the left side throttle body has a sacred throttle stop, the right side is simply cranked around to match. (The flow quantity doesn't need to be measured it's done by balancing the bodies)

So lets evaluate the left side throttle body what's it set to do?  Flow a known amount of fluid with the butterfly at rest on the stop under Conditions A.

The fancy flow bench sets up the standard conditions to use for the measurement. lets call this Condition A and Quantity A

Now suppose you set up the same body under a different set of conditions, it would flow a different amount wouldn't it? Lets call this Conditions B and Quantity B (exact same throttle stop setting)
But by the same token you should be able to take another buggered up throttle body and subject it to Conditions B then adjust it to flow Quantity B.
If you then subject it to Conditions A shouldn't it flow Quantity A?

As I probably told you I'm an instrument technician, something we understand is how to measure stuff.

I propose we set Conditions B so that anyone anywhere can measure Quantity B with a few simple items from your nearby hardware store.
« Last Edit: March 20, 2019, 05:04:30 PM by Kiwi_Roy »
72 Eldorado
07 Griso 1100
17 V7iii Special

Moto Guzzi - making electricians out of riders since 1921

Online Huzo

  • Guzzi Hero
  • *****
  • *
  • *
  • *
  • Posts: 6545
  • Location: Creswick Australia
Re: Ok. Here’s another one..
« Reply #4 on: March 20, 2019, 06:00:03 PM »
Damn right..
Close bleeds and slide a packer under throttle stop to open butterflies a bit.
This amount can be ascertained by starting the bike first and running it up to 3,000 rpm.
Use the same packer when you attach your shagged TB set up into the jig and dump the same volume through your left TB of unknown condition, this value should be the same as the known good one.
I’d flow a known fluid through a known good TB and measure the time taken to empty the tank..
Then attach the shagged one and check the results, if it flows the same as a good one, then attach an identical reservoir to the right one and adjust the bell crank.
It all hinges on obtaining data on dump rates through a known good set and farting around with the shagged ones to replicate the results.

 


Advertise your products today. All proceeds go back into this website.
Your ad will show up over 10,000 times daily!
Advertise Here