Throttle body sacred screw reset.

[tris]

I can't remember my thermodynamics/gas laws but will you get a consistent flow as the pressure drop, or don't you think that is of any significance?

[Huzo]

I can't remember my thermodynamics/gas laws but will you get a consistent flow as the pressure drop, or don't you think that is of any significance?

No Tris.
The flow rate will diminish as the pressure drops, but I will run several test dumps on a good set first, all I want is to get the same dump time as the good set.
If it performs identically, then the aperture must be the same on both sets.

[tris]

Aha - it's a comparator- got you now

[Huzo]

After all…
When they set a nominal flow rate ex factory, they’ve no idea how each engine draws in the mixture.
All I want is to replicate their datum, I’ll accept what I get after that.

[moto]

No Tris.
The flow rate will diminish as the pressure drops, but I will run several test dumps on a good set first, all I want is to get the same dump time as the good set.
If it performs identically, then the aperture must be the same on both sets.

Instead of only recording the mean for a series of runs, calculate the mean and variance. That will give you a much better idea of the precision of your measurements.

[Huzo]

Instead of only recording the mean for a series of runs, calculate the mean and variance. That will give you a much better idea of the precision of your measurements.

The plan was to fit a test plate to the outlet on reservoir with a small hole in it, before I started passing air through a TB.
I need to see multiple readings that do not vary, so as to learn to depend on the process.

[guzziart]

Dunno about your Le Mans…
The “sacred screw” is the euphemistic name given by a former member here on WG.
It is the setscrew that your throttle stop comes up against on your left (gear change) side throttle body.

Thanks Huzo! 
Yep, I definitely have messed with that thing (grub screw) on my '03 V11 Lemans in accomplishing a decent tune-up.   https://www.v11lemans.com/forums/topic/19610-decent-tune-up/
Ok, I learned something new today that I didn't know yesterday.
Happy 4th all!

Art

[Huzo]

Well, I’m up to here…

https://youtube.com/shorts/hvYAoeYDLN0?feature=share

https://youtube.com/shorts/NGHMAry4iks?feature=share

The water is hard to see, so I’ll maybe add some dye, or place a foam floatation ball in the top, to mark the level.
I have a small bleed on the spigot weld that I’ll attend to. But the dump rate looks like it will be manageable.
I always hoped for around 30 seconds.
The next stage is to remove the TB’s and plug the spigot, then track down any air bleeds.
I’ll know I have achieved this by running the manometer up to the top and testing that it holds without descending.
I’ll then know that ALL of the escaping air during the dump, is flowing through the TB.
Once I can get to there, I can do multiple dump runs and ensure that the results are repeatable to within tolerance.
Armed with this data, I SHOULD be able to attach a molested or worn set and set it to the same flow rate…

[Frenchfrog]

Looking good huzo !

[Huzo]

Looking good huzo !

Thanks mate..
Watch your head on that beam on the way down !

[Frenchfrog]

Easy solution : just use the windows 

[tris]

Re minor leaks - try this https://www.henkel-adhesives.com/us/en/product/threadlockers/loctite_2900.html

You're not welding a nuclear sub so might save you some effort

[Huzo]

Re y,minor leaks - try this https://www.henkel-adhesives.com/us/en/product/threadlockers/loctite_2900.html

You're not welding a nuclear sub so might save you some effort

Thank you for your interest Tris.
If I’d run out of ideas I’d investigate that method, but then if it started to leak during testing and I didn’t know, then I’d be mal adjusting the screw to set the dump rate correctly.
The thing to do is track down the source of the leak and fix it.

[tris]

Its useful stuff.
You can torque a nut down and then apply the Loctite
When the speed sensor died on the B1100 I decided that I wasn't going the cough up £300 to replace it, so went with an industrial sensor (about £35 all in)
I used the 2900 to stop it unscrewing and ending up in the brake disc

[Huzo]

Well, I’m a fair way along…
I have the apparatus built and as proof of concept, I think I’m gonna’ be ok. This shot shows some preliminary dump test time data and there are a few interesting points.



The times recorded in column #1 vary very little and I’m encouraged by this.
As you can see, the times vary no more than 0.5 seconds either way, so this reflects around one second in 60 or about 1.5%
Not too bad I reckon.
In the second column, you’ll see that the times jump by about 1.5 seconds.
That was after I opened and then closed the throttle body butterfly. I took this to signify that the butterfly came to rest in a different position the second time. That may not be significant in the scope of things, but worth noting.

Interesting also I thought, that reducing the distance from one metre to half a metre, took the time from 30 odd seconds to 10 or so. This highlights the fact that the dump rate diminishes as the pressure approaches ambient.
But we all expected that.
I think that a distance of about 800 mm should be a good compromise. In any case it should be remembered that whatever test parameters are employed with the control set, that’ll need to be the same form there on.
That should be achievable.
Anyway, here is some of the action…
https://youtube.com/shorts/zZlspieRKUE?feature=share
https://youtube.com/shorts/L4X_gHjTis4?feature=share

[Huzo]

Well, I got there…
Now all I need is a good quality unmolested set of 45 mm throttle bodies, then I can get a data set on the dump rate.
I am getting numbers within 0.2 seconds each side of 19.2 seconds over an 800 mm dump.
That is on my old set from the Norge.
Once I have a good quality set to take a calibration from, I’ll be able to restore a molested set to health.
Pete Roper can loan me a new set of 50 mm ones along with a selection of molested 50’s.
The idea is that he’ll fit them to a bike and see how they stack up. But for my purposes I’ll need 45’s.

[Frenchfrog]

Impressive work Huzo...if you can crack this then that will be a first in the Guzzi world!

[Huzo]

Impressive work Huzo...if you can crack this then that will be a first in the Guzzi world!

Yeah FF.
Talking to Pete today, he made the legitimate point that I won’t be able to resurrect a badly worn set, but I’m certain I can bring a molested set back to factory setting.

An example might be, someone has a 20,000 km Norge and has manipulated the sacred screw in a vain attempt to reset the idle when perhaps it was a stepper issue.
That would be the sort of thing that was able to be restored.

[Frenchfrog]

Yup...and there has to be a few people who have done that to a good set of bodies.As the bikes get older there will be less good spares around so what you are pioneering might just save someone else's bacon too. Well done mate !

[Pescatore]

Sounds like a fun hobby: recalibrate TBs.
What's next?  Play with the 50mm TBs?

[Huzo]

Sounds like a fun hobby: recalibrate TBs.
What's next?  Play with the 50mm TBs?

I think it will come to that.

[Huzo]

I’m looking to get hold of a known good set of unmolested 45 mm throttle bodies, to do some calibration runs.
Just for temporary loan, but I have to get some numbers to achieve a base line.