SIMPLE MOD MAY SOLVE POD TUNING HARDSHIPS!

+1 on what Fitz said. A good look at it was the pictures that ManBot put up on another thread showing how the boots mate to the opening in the carb intake. Definately shows that they have an integral part in the intake process.

What would be interesting to see would be for someone with carb that has been cut in half to put a piece of clear plexiglass or something over it and run smoke through the carb with the intake boot and without to see the turbulence effect first hand. Just a thought.

 

So, this thread is a year old (just shy), and I still do not know if anyone has tried the RickCoMatic fix and run their bike for a few thousand miles. Are there any road results out there?

 

Alright, excuse me if this has alteady been tested, but what about drilling into the top hat of the carb? Rather than from the carb body?

 

The Top Hat on the Carb seals the Diaphragm Chamber and allows the Vacuum to form raising the Piston.

What is needed is a supply of Atmosphere BELOW the Diaphragm.

To feed MAIN Air.
To allow the Diaphragm to collapse.

The shortcut to achieving this scenario is:

Cap the Kidney Shaped Atmosphere Vent on the face of the Intake Horn.
DRILL a 1/4 Inch Hole in the Intake Horn, ... behind the Vent to the side of the Band where the Rubber Boot gets affixed.

Stick a Quarter Inch Grommet in the Hole.
Attach a miniature filter.
Increase the Size of the MAIN AIR JET
Experiment with Emulsion Tubes drilled with extra Air Venting Holes
-OR-
Drill the existing Holes ... Incrementally larger from bottom to top
-OR-

BOTH!

 

As a temporary test, could a baffle be placed over the vent hole? A small piece of aluminum can, folded and seated under the pod lip with a gap at the face of the vent, should reduce the extremes of pressure fluctuation and maybe give a clue to what's going on.

 

The Atmosphere Port on the Face of the Horn does need to be Sealed.
A Plastic cut-out epoxied in place should suffice.
Or, a Plug fabricated from a Gum Eraser and secured with Contact Cement would be equally as effective.

Each Body needs an Aux Vent.
Drilled to the rear of the Atmosphere Vent to provide a source of Atmosphere to feed the Pilot and Main Air Jets plus allow the Diaphragm to collapse when there is a Pressure Varient.

Initially, there was an uproar from those concerned about ruining the Carbs with the Aux Atmosphere Vent getting drilled through the Carb Body.

Any sized Hole drilled in the Carb can be easily PLUGGED with any of a wide variety of Rubber Stoppers and Plugs available in the aftermarket.

After the Atmosphere question is resolved; the SIPHONING VOLUME of Main Jet Supplied Fuel needs to be addressed.

The MAIN AIR Jet would need to be enlarged or simply removed.
The MAIN NOZZLES (a.k.a. Emulsion Tubes) also need to be altered to allow MORE Main Jet Fuel to be Siphoned-up into the Intake Stream.

Additional Holes of the same size drilled between each of the existing holes.
•Or•
Enlarging the AIR Bleeding Holes --> Incrementally <-- to regulate the amount of Fuel getting Siphoned-up into the Intake Stream to remain close to the optimum stoichiometric (1) ratio to assure maximum performance throughout the Power Curve.

Finding the solution may also involve:
Different Sized Diaphragm Piston Needle Valves
Shimming
Altering the Single Hole at the Bottom of the Diaphragm Piston.
Possibly adding an additional hole in the bottom of the Piston to lower the pressure in the Diaphragm Cavity making the Needle rise more quickly.

(1) http://www.engineeringtoolbox.com/stoic ... d_399.html

 

It may sound a bit too simple but a way to make that mod reversible and to repeat the experiment numbers of times could be to shape rubber pieces to fit snug in the kidney shape tunnels.

In a try-and-error process, one could drill each rubber plug with different bit sizes prior to push them in place, to allow different amounts of air to go through those kidney passages and see if a specific diameter is the best.

Then it might be useless to drill the top of the carb intakes. The carb rack used for experiments wouldn't get messed up.

Or a different way to experiment could be to shim a jet with two rubber pieces in the kidney passages, and experiment with different jet sizes...

Just my two cents.

 

The "Bypass" theory involves SEALING the Kidney Shaped Atmosphere Orifice, NOT regulating its size.

We need to PREVENT air from flowing across that Orifice.
When Air flows ACROSS the Orifice, pressure within the Cavity behind the Vent is LOWERED.

Sealing the Opening on the face of the Horn and providing Positive Atmosphere to the "Below-the-Diaphragm-Rubber" Cavity is necessary for the Bypass to help eliminate the Lean Condition of naked PODS.

 

All right, so why not use properly shaped rubber plugs to block these orifices? They would be more easily removed than metal solder if one wants to reverse the mod.

 

Ok, I am just curious about something in this theory. I noticed while cleaning the carbs, that when air from a blowgun is passed over the kidney shaped holes, that the pistons slam open. having the throttle open or closed made no difference on whether air passed over the orifices raised the pistions. So my question is how will the pistions rise with this port plugged??

 

The Atmosphere Vent Bypass is still on the drawing board.

My initial concept involved drilling and plumbing.

Eventually, we Plugged the Atmosphere Vent with a Plug that had an integrated External Air Vent running through the Pod.

::::: Integrated Vent Tube Through Pod :::::


Rather than hassle with running a Vent Tube through the Pod, ... it would be easier to:
• Drill a Hole in the Carb Body to the Front of the Horn
• Install a Grommet
• Add a Plug-in Filter.

The Bypass only solves the problem of Negative Atmosphere at the Vent Opening that causes a lowering of pressure in the Cavity below the Diaphragm Rubber.
> Causing the Diaphragm to not easily collapse.
> Starving the Pilot and Main AIR Jets contributing to the LEAN Condition.

We still need the MAIN JET Supplied Fuel Siphoned-up the Nozzle AND Atomized as it enters the Intake Stream.

>> Additional Holes in the Nozzle (Emulsion Tube)?
>> Incrementally enlarged Holes in the Nozzle?
>> Larger or eliminating Main AIR Jet?
>> Larger or additional Hole in the Bottom of the Diaphragm Piston?

 

:lol: ok, then why on earth just plug one hole to create another. All this seems to accomplish is moving where the carbs draws in the atmospheric air. Also creating a need to make a filter on this new opening. When I first started following this thread, I was really intrigued. But stumbling on the effects of air on the kidney opening myself on accident, got me thinking a bit more anylitical about this whole topic. So, it seems to me that this kidney shaped hole is just "there" to provide filtered atmospheric air a place to enter the carb. So when the butterfly valve is opened, that pressure differtial makes air move in thru the kidney hole, and lift the piston. So it seems that this is putting the cart before the horse, so to speak,since what is not being addressed is the increased volume of air supplied by the pods instead of the balanced volume of air supplied by the stock filter box.

 

"since what is not being addressed is the increased volume of air supplied by the pods instead of the balanced volume of air supplied by the stock filter box."

We fought about this back in 2006.
We know there's more air!
The problem is the AIR is NOT Shaped or Accelerated.

We acknowledge the Volume of Air is increased.
We're trying to do other things than just ... "Re-jetting"

Re-jetting, ... alone ... won't solve the problem.

 

The KIDNEY-Shaped Hole IS the Atmosphere Vent.

When the Rubber Boot is affixed to the Carbs Intake Horn a captive volume of AIR is moving Toward (an AT) the Vent.
A POSITIVE Atmosphere is present, there.

When a POD is affixed.
Intake Air cascaded into the Intake Horn.
The Intake Air flows OVER and ACROSS the Vent.
The Pressure is REDUCED at the Vent Hole.

This is why Sealing the Vent at the face of the Horn and Providing a Aux Vent elsewhere is necessary.

 

wow I only read the first and last page,one lil bit from me maybe dumb but...I think my GPZ carb may have the aux vents installed stock,? If I am mistaken please excuse my ignorance rick was this proposed solution possibly inspired by another carb design? will follow up and read this whole thread as i am rivoted by the whole drama of it!!!!!hahah

 

what about upgrading carbs instead of doin g all that drilling just replace for a set of say xs1100 carbs ?? what would be a good swap

 

Putting a set of bona fide racing carbs on, from Keihin or Mikuni would make having Air Pods to look at a whole lot easier.

$700 -to- upwards of a grand!

For a cosmetic mod!

Maybe a couple of ticks faster in the quarter-mile, ... but not a whole lot more to gain at top end.

I've heard a few stories about guys who bought Carbs of an early '80 Kaw Police Bike and tried to make them fit a 750 Max and Seca.

I doubt they are a bolt-on substitute.

 

wouldnt xs1100 carbs do the trick ?

 

Members and Visitors,

I probably shouldn't be posting this because of my POD ignorance, but what the hay. Rick, you're suggesting plugging the Atmosphere Ventura, installing a small filter below the diaphram in the carb body right behind the ventura vs plumbing the PODS to compensate for the un-stacked large amount of air moving across the ventura with PODS and modifying the emulsion tube, diaphram piston, main fuel jet, needle and or a combination thereof in order to get the proper air/fuel mixture through each carb body, right? Sounds like a plan, but how would you locate the filters on carb body #2 and #3 without changing the Atmospheric air flow by adding a piece of hose to make the connections in the limited space between the carbs? The process of modifying/testing the main fuel components in order to get the diaphrams to rise and drop providing the proper main fuel flow makes my brain hurt. 8O Then again, how much and what type of fruit do we bare without the work. You are a intelligent man, and although I plan to stay with the stock set-up I hope you and others find a solution to the infamous PODS for the sake of all those members who wish to use them. Lastly, I did state I'm ignorant to PODS so I feel comfortable saying this...Why not ask a company to manufacture a set of PODS say with built in restriction at the Ventura? Yeah, I know...good luck with that one. Okay, everyone can laugh now. :lol: 8O

Gary