Throttle body sacred screw reset.

[Huzo]

A couple of years ago, someone here in Australia sent me a set of great quality but molested throttle bodies.
If it was you, could you contact me please ?
I’m going to resurrect them.
Thank you BTW…

[Huzo]

Jeeez…
There can’t be that many of us…

[tris]

Perhaps they sent you the TBs because they were getting out of Guzzi ownership so not on here any more??

Good luck though in your search

[Huzo]

I’m going to try this…
As mentioned I have a set of good quality but possibly molested TB’s.
My current set have 210,000 km on them and are showing signs of wear. I have embarked upon this piece of work.




We all know that the TB’s are set to flow a given amount of fluid (air) at the factory and this is the condition in which they are delivered. Mine are flowing more than they should I expect, due to leakage around pivot spindles and grooving of the bore.
More on this later.
The rudimentary diagram shows the principle I wish to investigate.
Blocking the egress will allow me to load the system with Methylated Spirits and purge the system of air by allowing bubbles to float up and surface. As I remove the plug, I can time the dump from the top index mark to the bottom and record that time, averaging over several samples. This will remove the anomaly of differing amounts of “head pressure” contaminating the results due to differing rates of flow.
I’ll use Methylated Spirits because it will flow more readily through the small aperture around the butterfly.
If I achieve a dump rate off say, 20 seconds on my control set, I can then hook up the molested set and perform the identical procedure on them
I SHOULD be able to manipulate the sacred screw to obtain an identical rate on the new ones.
Now I concede that my originals will be flowing too much fluid and so therefore will my replacements, but I can reduce my flow rate on the recalibrated ones by a percentage amount to simulate what a new set would produce.
I will listen to advice on this..
Also an added benefit of this approach, is that I can witness how much my “new” set leak, compared to the worn ones. In addition I can do an approximate balance with the liquid before I fit them for real.
At least I know they will be clean when I fit them…!
I don’t think my first attempt will seal properly around the TB intake, but I will need to achieve this because I have to know that ALL of the fluid is passing by the butterfly and not escaping.
I would dearly love to get hold of a new set for an hour….
Now…
Please don’t flame me, I’m using metho….

[Huzo]

Perhaps they sent you the TBs because they were getting out of Guzzi ownership so not on here any more??

Good luck though in your search

Yeah, thanks Tris.

[tris]

Nowt wrong with the theory H, and a similar method was discussed in the past when I was messing around with TBs on my B1100
The problem is that you don't know if the reference set is right.
When Luigi flowed them initially he almost certainly was told to get the flow between two set points, and you cannot know if they are top or bottom limit.
To eliminate that problem then statistically you need to check 30 different unmolested TBs which isn't practical
That being said, your plan would be a good comparator and wouldn't hurt anything.
Personally I like the "isolate the ICV and see if the bike idles at 1K"  as a check
Keep us in the loop as to progress, I might not have a B1100 anymore but every day is a school day

[Huzo]

Nowt wrong with the theory H, and a similar method was discussed in the past when I was messing around with TBs on my B1100
The problem is that you don't know if the reference set is right.
When Luigi flowed them initially he almost certainly was told to get the flow between two set points, and you cannot know if they are top or bottom limit.
To eliminate that problem then statistically you need to check 30 different unmolested TBs which isn't practical
That being said, your plan would be a good comparator and wouldn't hurt anything.
Personally I like the "isolate the ICV and see if the bike idles at 1K"  as a check
Keep us in the loop as to progress, I might not have a B1100 anymore but every day is a school day

Yeah Tris, I reckon all that is within the frame of correctness.
The way I see it as you eluded to, is that I am essentially calibrating mine to a worn set, so will be on the lean side..(dragging too much air), but I can reduce the plate opening fractionally by increments so will head down that route.
As you say, nothing ventured nothing gained.

[Huzo]

I did 10 dump tests on the control set and found that the dump time increased incrementally as I repeated each time.
If I filled the TB and did a fast dump, then the dump times dropped back from 18.5 seconds to 17 seconds.
I deduced that contaminant was accumulating between the bore and butterfly.
So I did 3 dumps then a flush…(sounds  like good advice….) 
I ended up getting the same dump time on the replacement set as my originals.
I then gave the sacred screw a quarter turn to test the dump time percentage increase. One quarter turn alters the dump time from 18 seconds to 25..!
It really is that sensitive.
Suffice to say that I set my replacements to the same dump rate as the originals, then closed the butterfly to give a 2 second slower dump time…
Time will tell.
I now have this to deal with


I took the manifold fitting off to check the condition of the O ring and twisted a bolt off… The broken one is in the shadow.
Now I have to fix that…!

[tris]

Well you're making some sort of progress 

Hopefully the stud wont be too difficult to extract!

The sensitivity is concerning as of a M3 coarse thread (my guess) means the tip advances 0.125mm (5 thou) in a 1/4 turn
A human hair is 0.017mm to 0.181mm in diameter (Wikipedia) so would take very little to make things go awry based on you assessment so far
I guess that the objective is to get it close enough for the ICV to be able to control things without hitting the limits

Good Luck and Carry On!!

[Huzo]

Well you're making some sort of progress 

Hopefully the stud wont be too difficult to extract!

The sensitivity is concerning as of a M3 coarse thread (my guess) means the tip advances 0.125mm (5 thou) in a 1/4 turn
A human hair is 0.017mm to 0.181mm in diameter (Wikipedia) so would take very little to make things go awry based on you assessment so far
I guess that the objective is to get it close enough for the ICV to be able to control things without hitting the limits

Good Luck and Carry On!!

Hmmm….

[Huzo]

Okay…
The job of resurrecting the molested TB’s is finished. As mentioned, I did several dump tests on the original TB’s and recorded the results.
This is the apparatus.





actress tierney crossword
Each successive dump time increased slightly and I think it was due to contaminants collecting around the butterfly plate, I hold this view because each time I did a flush dump, the time reverted back to the original.
If I were to do it again, I would do a timed run and then a dump before the next. The nominal dump time was 18 seconds, so it was a matter of hooking up the molested set and manipulating the screw to achieve that time.
Now the tricky bit was…
Because I was using a set of worn bodies to gather the data, it was now time to decide how much I should reduce the aperture to (hopefully) replicate the flow of a new set. I opted for a 10% reduction in the aperture to reflect a dump time of 18+1.8=20 seconds.
I did all that and this is what happened after a subsequent balance and TPS reset.
https://youtube.com/shorts/RWXodWt9PK8?feature=share
The pickup from any revs is crisp, with an 1150-1200 rpm idle.

I have an idea of a pressure vessel with a manometer plumbed into the reservoir and a flexible pipe to a set of TB’s.
After bringing the pressure up slightly and if the volume of the reservoir was enough, you could open the valve and flow the air through a pipe into the TB. The pressure drop in the reservoir as it dumps through the TB, will be shown as a reducing pressure reading in the transparent manometer tube.
Timing the pressure drop from (say) 1.2 atmospheres to 1.1 would be reflected as a time interval on the transparent manometer. What you need is a high volume reservoir but low pressure, to give a repeatable steady flow.
Suffice to say that what we are doing is providing a flow of air through the TB and timing the “dump”, if you will.
If you did that for a new unmolested set, then you could hook up the molested ones and manipulate the screw to give the same dump time, but this time you’re using air, so no contaminant collection around the throttle plate.
It’s like a flow bench that produces a unique dump rate or time, that can then be applied to a molested set.

[fotoguzzi]

So after all this you could reset a molested sacred screw? Or not? Is that the objective?

[Huzo]

So after all this you could reset a molested sacred screw? Or not? Is that the objective?
[/quote]Yes, I cannot see why anyone couldn’t.
This is the plan I have.


Although I’m happy that I got the new TB’s back to ok, I do admit there was a bit of faffing around decontaminating the aperture between dumps.
I think this is cleaner and more akin to what is done at the factory and in general use.
So we turn off the communication tap.
Bring the pressure up to 1.5 atmospheres (if applicable), then open the tap with the water slightly above the top mark so as to be ready with the stopwatch as it passes on the way down.
The rate at which the pressure drops and thus the fluid in the manometer, will be a function of the amount that can get past the throttle plate.
Once you have a figure…Rinse and repeat…..Call it 10 seconds.
Connect the rooted set and adjust the SS to give the same result.
Because 1 atmosphere is 400 inches of water, I can see that 1.5 atmospheres is going to necessitate an unwieldy amount of “head” (so to speak) and that may prove to be the fly in the ointment.
A denser fluid will probably be in order.
But also, maybe 1.1 atmospheres may provide a flow for an acceptable time to gain good data. The pressure is a factor, but the volume of the reservoir is what determines how long the air will flow.
Many times I have disconnected a fitting from my compressor when there was only a low pressure in the tank and it took some time to stop flowing and equalise.
Experiment will answer the questions.

[Huzo]

I have a couple of threads running at the moment, so I’ll drop my question on this one.
As mentioned, I have my molested set of almost new throttle bodies very close to spot on with the liquid dump procedure, but until I have my air apparatus going I’ll not be able to get a better result, suffice to say though it’s running beautifully but possibly a bit lean and here’s why I suspect it to be so….

On two occasions upon stone cold startup I have downchanged after one minute riding approaching a stop and in the usual way, pulled in the clutch when close to stationary. At that point the engine coughed and died, but with NO INTERVENTION from me, the starter engaged and the bike fired right up…!
Does anyone know what allows this and have you had it happen ?

[normzone]

The starter engaged with no intervention from you?

Sounds like "Rise of the Machines" or any other Skynet/Terminator reference. The singularity is upon us.

[blackcat]

"At that point the engine coughed and died, but with NO INTERVENTION from me..."

Just a guess but have you looked at the stepper motor?

[Huzo]

The starter engaged with no intervention from you?

Sounds like "Rise of the Machines" or any other Skynet/Terminator reference. The singularity is upon us.

It has done it twice when the engine coughed and stalled when cold.
I’m not joking….It did.

[Huzo]

"At that point the engine coughed and died, but with NO INTERVENTION from me..."

Just a guess but have you looked at the stepper motor?

Yes I have, it has a new one and at all other times now, it’s exemplary with an 1150 rpm idle. When I get my airflow apparatus built, I will be able to match it perfectly to a known good set. I think I have the plate angle a tiny bit too open. I can close the sacred screw fractionally. Re balance the TB’s and reset the TPS if I wish and that will essentially richen the mixture a bee’s dick. For now I will not, until I have this thing producing repeatable results.

[Vagrant]

Witchcraft!

[Huzo]

Witchcraft!

Do you have a view as to it’s potential efficacy ?

[normzone]

Witchcraft!

"I got better ..."

[Huzo]

I’ve commenced work on the airflow apparatus that I think I’ll be able to recalibrate throttle bodies with.
It’s fundamentally what I’ve shown in the above diagram and I’m up to here.


Fitting the spigot in the end allows me to fit a TB directly to the reservoir


The vertical spigot in the top will supply the manometer and the brass fitting will be the supply from the compressor.
The input has a valve so when the reservoir has been loaded and the manometer is at the top mark, it can be isolated so no airflow can occur back through the compressor.
That would result in contamination of the dump rate figure.
Y’all can see that I have departed somewhat from the initial schematic, the reservoir will be charged remotely and there will not be a valve between the reservoir and the TB. The process will be to charge the reservoir to just above the top mark on the manometer, with a rubber bung in the outlet of the TB.
When the pressure is just above the top mark, remove the bung and air will flow and the level in the manometer will start to fall.
Timing starts as it passes the top mark and stops as it passes the bottom mark.
It’s just simpler with no complication.
Once the apparatus is built and with no TB fitted, I will plug the end of the outlet and charge the reservoir, sending the level up in the manometer. It will not pass unless I can take the manometer up to the top mark and walk away for 10 minutes and no drop recorded on the manometer…..NONE…!
Then I can be confident in the tests, that ALL of the air dumping from the reservoir, is flowing through the good TB.
If anyone can tell me why I cannot then set a molested TB set to the same value as a new control set, I’m prepared to listen.

Anyway, more soon.

[moto]

I believe Kiwi Roy did something similar sometime ago. I analyzed his data and showed that his apparatus was accurate enough to set the screw. I don’t think anything came of this in the end. You seem to have a lot more throttle bodies than he did. What will you do with them?

[Huzo]

I believe Kiwi Roy did something similar sometime ago. I analyzed his data and showed that his apparatus was accurate enough to set the screw. I don’t think anything came of this in the end. You seem to have a lot more throttle bodies than he did. What will you do with them?

I think Roy used a liquid, but I could be corrected. I only used the methylated spirits to get a rough as guts approximation so I could use the heavily molested ones that I was given.
I only have 2 sets, the original ones from my Norge and the donated ones. I still need to get hold of an unmolested set that I can use to gather data.
When Pete Roper gets his hands on a known good set, I’ll use them to calibrate my air flow instrument.
He has a known good 50 mm set, but I need data for the smaller (40 mmm?) ones.

But I’ll get there.

[guzziart]

Hi All,

Stupid question here.....Where is the "sacred" screw located on the TB (picture please, no artists conception)?  And, which bikes have it?  I've got an '03 Lemans and have messed with all the TB screws on that thing...it runs like a champ.

Thanks,

Art

[Huzo]

Hi All,

Stupid question here.....Where is the "sacred" screw located on the TB (picture please, no artists conception)?  And, which bikes have it?  I've got an '03 Lemans and have messed with all the TB screws on that thing...it runs like a champ.

Thanks,

Art

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.
This one…




It inherited the name because it is not to be adjusted in an attempt to get the idle speed correct. The left TB is set at the factory to flow a given volume of air per unit time and the right hand one is balanced to the left one by a manometer or similar.
The TPS is then reset digitally so that it recognises the throttle plate in the right hand TPS equipped TB to be at 4.6 degrees nominally.
The idle balance is then set by opening ONE air bleed from closed.
That’s a rough as guts description, but that’s about it.

[Pescatore]

Go Huzo, go. Very interesting project.
Looks like a compressor has also been molested in the process.
Can you also balance the other TB with this setup, or does it have to be done with the bike running?
Do you need an air filter somewhere? Who knows what gets sucked into the tank.

[moto]

I think Roy used a liquid, but I could be corrected. I only used the methylated spirits to get a rough as guts approximation so I could use the heavily molested ones that I was given.
I only have 2 sets, the original ones from my Norge and the donated ones. I still need to get hold of an unmolested set that I can use to gather data.
…
But I’ll get there.

I am sure you will.
Kiwi Roy used water, which has lower viscosity than alcohol.
Good luck with your airflow system. This would be a great case for a YouTube video.

[Huzo]

I am sure you will.
Kiwi Roy used water, which has lower viscosity than alcohol.
Good luck with your airflow system. This would be a great case for a YouTube video.

Methylated spirits will pass through a smaller aperture unhindered than water, it has a lower surface tension.
If you try to pass water through a fine gauze like a fuel strainer, it will often as not be unsuccessful.
The old remedy for water in fuel, was to add methylated spirits which reduced the surface tension and allowed the water to pass through.
Their viscosities are very similar, although metho is slightly less dense.

[Huzo]

Go Huzo, go. Very interesting project.
Looks like a compressor has also been molested in the process.
Can you also balance the other TB with this setup, or does it have to be done with the bike running?
Do you need an air filter somewhere? Who knows what gets sucked into the tank.

A couple of things there.
You could set up the flow rate to be the same on the apparatus, but on your engine the differing wear on rings, valves/guides etc. would draw air at different rates, so you’d still need in situ balancing, but I imagine you’d get it close.

As for contaminants in the tank.
The flow rate is very low during the dump, the reservoir is only being charged to about 1 metre of water, which is 0.1 atmospheres.
I haven’t worked out the volume of the tank yet, but it looks about 50 litres, so that should produce a low but steady flow rate. I don’t envisage contaminants being picked up.