What does the air cutoff valve on the carbs do?

[BigBluef6]

What does the air cutoff valve on the carbs do?  I did searches and found people testing them, replacing o-rings on them, buying new ones and replacing them, and spraying them with ether to test for leaks, but cannot find any description of what they do.  Clymers just says when you disassemble the carbs to take them off and when you reassemble the carbs, put them back on.  There is no description of functionality.

I have been chasing a extremely rich carb problem for months on 100% OEM carbs and beat to death the fuel side of the equation.  Now I want to look in detail on the air side of the equation.  For that, I need to know what the air cutoff valves do.

Thanks.

[gordonv]

I believe it was mentioned that the air valves are for adding air into the exhuast, to burn the unburnt exhuast gases.

(I'll delete this post if I am wrong, by anothers reply)

[Ricky-D]

Here ya go-

The air cutoff valve is a simple but vital component of the carburetor system on GL1000s. It's function is to eliminate backfiring on hard deceleration (throttle fully closed). Hard deceleration creates a high vacuum signal in the intake tract which activates the valve. When activated, it restricts the flow of air to the external idle circuit air jets thereby richening the mixture. This slightly richer mixture is calibrated to eliminate backfiring in this operational mode.

From:  http://www.randakks.com/TechTip3.htm

A quick Google search revealed many sources for information. Something easy, a caveman could do it.

***

[98valk]

not knowing your experience/background, but why do u think it is running rich? symptoms?

[BlueValk]

What does the air cutoff valve on the carbs do? 

Thanks.

I believe that upon deceleration, they cutoff some air to help stop popping.  They are vacuum controlled and are adjustable (though, that would be a chore).

I guess if they are stuck on, you could run rich.

BlueValk

[Bigwolf]

Bigbluef6, What bike are you working on?  Is it an F6C or is it a Valkyrie?  The reason I ask is because the fuel and air delivery is quite different between the 2 bikes as well as several other not normally noticed differences.

If you have an F6C with the main jets for a OEM Valkyrie, you will have exactly the problem you describe.

The cut valves are as Ricky-D quoted.  The cut valves on my Valkyrie are not adjustable and they were bad at 25k miles.

Bigwolf

[BlueValk]

Wow, all 6 cut-off valves went bad!  In 12 years on this board, I don't remember hearing of even 1 going bad.  But, if you say so ....

The adjustment is 'inside' the carburetor.  The cut-off valve has to be removed to get to it.  Even if one did do that, an accurate or precise adjustment would be real tough.

But, the question was, what do they do.  They cut off extra air (that is normally added) during firm deceleration.  It is similar to the pair valves.  But, unlike the pair valves, instead of adding the air to the exhaust gases, it adds it to the mixture.

If you put a mechanics stethoscope on the valve, you can hear it clicking at an idle.

Hope that helps some Bigblue.
BlueValk

[Bigwolf]

Wow, all 6 cut-off valves went bad!  In 12 years on this board, I don't remember hearing of even 1 going bad.  But, if you say so ....

The adjustment is 'inside' the carburetor.  The cut-off valve has to be removed to get to it.  Even if one did do that, an accurate or precise adjustment would be real tough.

All 6 of the cut valves on my Valk would "cut" the air when the vacuum reached 15.7 in. of hg (Honda spec) but only one of them would hold the vacuum as they are supposed to do.  So to be precisely correct, only 5 of the 6 were bad.  And they were only bad because they were leaking vacuum.  Even so, bad is bad.

I see no adjustment under the cut valves in the carb bodies on my Valk.  The 2 holes to the right are where the cut valve goes.

The air cut valves control the air to the "pilot" circuit so you can/do adjust the fuel in that circuit when you adjust the pilot screw. 

Bigwolf

[Ricky-D]

You can plug all the related holes in the carburetor (air cut valve) and have no effect upon the bike's running.

It may pop a little more on deceleration but that would be the sum total of the modification.

Plugging all the holes will not affect the lean/rich fuel settings.

***

[Red Diamond]

If your bike is running rich, the pilot screws are not set properly. Mine was running so rich, when at idle gas fume smells would get into my clothes. I pulled the carbs to check for dirtiness but they were clean. Set the pilots back to factory specs and alls well. 2 and 1/4 turn out from lightly seated.

[BigBluef6]

Wow, all 6 cut-off valves went bad!  In 12 years on this board, I don't remember hearing of even 1 going bad.  But, if you say so ....

The adjustment is 'inside' the carburetor.  The cut-off valve has to be removed to get to it.  Even if one did do that, an accurate or precise adjustment would be real tough.

But, the question was, what do they do.  They cut off extra air (that is normally added) during firm deceleration.  It is similar to the pair valves.  But, unlike the pair valves, instead of adding the air to the exhaust gases, it adds it to the mixture.

If you put a mechanics stethoscope on the valve, you can hear it clicking at an idle.

Hope that helps some Bigblue.
BlueValk

Yes sir.  That is the info i was looking for. Thanks.   

[BigBluef6]

Bigbluef6, What bike are you working on?  Is it an F6C or is it a Valkyrie?  The reason I ask is because the fuel and air delivery is quite different between the 2 bikes as well as several other not normally noticed differences.

If you have an F6C with the main jets for a OEM Valkyrie, you will have exactly the problem you describe.

The cut valves are as Ricky-D quoted.  The cut valves on my Valkyrie are not adjustable and they were bad at 25k miles.

Bigwolf

It is a 2001 standard Valkyrie.  What i meant by OEM is that all the carb parts are what came on the bike.  No after market jets, no aftermarket needles, no shims.  No other crazy mods that might be floating around.  I just cleaned all the original stuff.   

[BigBluef6]

not knowing your experience/background, but why do u think it is running rich? symptoms?

Ok, you asked.  Here it goes.   

The bike sat for year due to neck issues.  That is now fixed and time to get her back on the road.  I have cleaned everything in the fuel system from the gas tank (with both lacquer thinner and muriatic acid since each attacks different material) , replaced the fuel lines, through the fuel rails, through every piece of the carbs.  I installed the Red Eye o-ring kit in the fuel rails and carbs.  The one thing i did not do is soak the carb bodies.  Instead, i used parts cleaner and shot it through every passage i could find.   One knowledgeable gentleman suggested that soaking them might be essential.  I did replace the fuel valves (with Honda OEM) because the float levels were way out of spec according to Clymers.  I submerged all 6 floats under water looking for leaks.  I turned them every way i could thing of and gave them a little tap.  Zero bubbles.  I have dropped the carb bowls numerous times since cleaning the tank and there is zero dirt in the bowls.  I do have a Golon fuel filter.  The bike runs the same with or without the filter.  Plus a  filter issue would lean out the bike, not make it rich.

Now the bike starts, runs fine on the kickstand as she warms up (long enough to melt the headlight lens, but we won't go there now).  I start the bike with choke and slowly push it back up over about a 30 second period which is normal for my bike 11 years.  I start down the street and within a couple of hundred feet, it sounds like somebody stuff a pillow in the air box and she dies.  Yes the airbox is clean (no rodents setup house).  To rule out the "over oil the K&N" thought, i put the original air filter back in.  I kept the original since 2001.  If it was the kickstand switch, something would happen immediately upon putting it up and not several hundred feet down the street.  I switched the ICM and got the same results.  The bike will not start again until it cools off over night.   I live at sea level.

Immediately after she dies, i turn off the manual Pingel.  There is gas in all 6 carbs.  All 6 plugs are very moist and look identical.   The problem is consistent and reproducible.   Interesting that all 6 plugs look the same.  That tells me that that the issue is most likely a place in the system that affects all 6 plugs equally.  If only a couple of cylinders had an issue, the bike would run like crap, but still run.  I am not a believer of all 6 coils would go bad at once.  And it can't be just one coil because all 6 plugs look identical.   I have zero carb mods except IS springs.   All other carb parts, except the fuel valves from Honda, are what came on the bike which i bought new from a Honda dealer.  The bike ran fine since 2001 until i stopped riding her a little over a year ago.

I want to do another test before i rip the carbs apart again and soak them.  I want to find a peak voltage tester to test the pulse generator pickups.   The theory is that they are cutting off the spark to all 6 plugs due to failure.  I have no idea what a failed pulse pickup would react like.  I don't know if my symptoms describe what a failing pulse pickup would do.  But i am out of ideas.   
 
Are you sorry you asked?   

[YoungPUP]

Quick question. Whats the difference between a Valk and the F6C?

[Former BMW Guy]

Quick question. Whats the difference between a Valk and the F6C?

Yeah....what he said.

[YoungPUP]

Never mind  found it over on the norway site under models.

[Bigwolf]

Differences between Valkyrie and F6C can be found at this link:
http://www.valkyrienorway.com/MODEL%20DIFFERENCES.html
Most importantly, the air box setup is different, the main jets are different, and the exhaust is different.

I am not sorry CA asked a legitimate question.  Your answer to it helps a lot in trying to figure out the problem.  It seems you have already eliminated a lot of possibilities.  From what you said, it seems clear that the problem is heat sensitive.  Because of that I believe the carbs are not the problem.  I think you are on the right track checking electrical and you have already ruled out the ICM.  It might be one of the pulse generators but I don't think so.  I would check the voltage at the ignition coils when it quits and I would check to be sure the ICM has a good ground.  Since the bike sat so long and the way it is acting, I am thinking this could easily be a bad connection as in corroded terminals and/or grounds.  If that is the case, then it should show up as low voltage at the coils or show up as a poor ground to the ICM or it could show as low voltage to the ICM but would likely only do so after the bike has warmed up and quit.

Bigwolf

Bigwolf

[BigBluef6]

BigWolf, don't get me wrong.  I am very glad CA asked the question.  My "glad you asked"  comment was attempt at humor in regards to the War and Peace answer I wrote. 

Not to get sidetracked.  You made some good points and also sparked an idea to possibly add to your valid ideas.  Does the Valk have any kind of "over heat protection" that will shut it down before major damage is done?  I don't recall ever seeing it talked about here over the years and i don't recall reading about it in Clymers, but its worth another look.  Perhaps one of the sensors in the radiator sending signals back to the ICM to shut down.   Perhaps the sensor got mucked up after sitting for so long.  It's a stretch, but what the heck.

Back to the connection corrosion.  These are the tricky little buggers to find because of the number of places they could be.  In addition to taking some voltage measurements, I have some stuff called DeoxIT Fader Lube that i use to clean the pots on electric guitars.  Its made to clean and lube electrical connections but not melt anything.  I would feel comfortable hitting any connection with it.  Specifically about the ICM, i read another thread talking about a similar problem and it turned out to be the ICM ground.  The accessibility of the ICM makes it a good a place to start.  I'll see if i can hit this weekend.  Many thanks for the brainstorming.  Stay tuned…..

[98valk]

there is no over heat shut off mentioned in the tech manual.

bad gas can cause wet plug issue.
weak battery, or bad voltage regulator and/or alternator. increased rpms reguires more voltage to be supplied to the plugs to fire more fuel. voltage to the plugs/ICM is not constant.

alternator brushes are recommended to be changed/checked btwn 40-60k miles

u say it idles fine, does it accept throttle while idling? does the tach needle smoothly go up and down with throttle application?

how far/speed did u go down the road before it fell on its face?

have u replaced the intake manifold O-rings?
 from sitting so long the float needles could be the problem, dried out, indentation preventing a proper shut off. indent usually can only be seen with magnification.

[BigBluef6]

there is no over heat shut off mentioned in the tech manual.

bad gas can cause wet plug issue.
weak battery, or bad voltage regulator and/or alternator. increased rpms reguires more voltage to be supplied to the plugs to fire more fuel. voltage to the plugs/ICM is not constant.

alternator brushes are recommended to be changed/checked btwn 40-60k miles

u say it idles fine, does it accept throttle while idling? does the tach needle smoothly go up and down with throttle application?

how far/speed did u go down the road before it fell on its face?

have u replaced the intake manifold O-rings?
 from sitting so long the float needles could be the problem, dried out, indentation preventing a proper shut off. indent usually can only be seen with magnification.

1. gas is fresh.  I will refresh again this weekend to make darn sure that is not the problem, assuming i don't get bad gas from the station.  I have been using the same BP for years in all my vehicles with no issues.

2. the battery is a couple of years old and i charge it over night slowly with a 2 amp charger.  Of course this does not guarantee the battery is working correctly.  I'll see if the local auto parts store can test a motorcycle battery.  I can measure the voltage coming from the alternator.

3. there is less than 40K on the alternator.

4. it idles fine and revs fine as it is warming up.  She has never died sitting on the stand warming up.  The tach is smooth with throttle application.  When i first got it running, i let her sit on the side stand long enough to make sure the fan came on and and the thermostat opened.  Both were successful at 220 degrees as expected and melted my headline lens in the process.   I might have one of those "for off road use only" bulbs.  I really never know when i might get the urge to rip through the backwoods with her.   

5. i ride down a residential street at less than 20 MPH for about 4 houses then dies.

6. the intake o-rings were replaced when i installed the Red Eye o-ring kit throughout the fuel rails and carbs.

7. i replaced the float needles with OEM parts from Honda.  The original ones in the bike caused the float hight to be way out of spec according to Clymers.  I suppose some of the tiny springs got a bit tired.  The new parts are within specs.  Early in the game, i thought i might have installed the float needles incorrectly, but there is essentially only one way to install them.  One idea here would be to shutoff the manual Pingle immediately after the girl dies, then measure now much fuel come out of each bowl.  The problem here is that i don't know what is normal.

There is one point i forgot to mention that might help.  When i first got the bike running after i cleaned and installed the carbs, I could ride around the block a few time before she died.  For each successive run, about 6, she dies quicker and quicker until now i can just go a couple of hundred feet.  That indicates to me that something is slowly breaking down.  I think i need to have the battery checked.

[98valk]

does the engine just cut out or does it start running rough like out of gas, but u give it more throttle and it still runs for awhile and then it starts to die?
if so its running out of gas and its not an electrical problem

are the bowl vent hoses still installed and clear of obstructions? no venting, bowls will go dry/low under engine load, engine dies.

clogged in tank fuel filter, if pingle uses one.
fuel filter in fuel line, sometimes a problem.

sounds like a fuel issue.

[BigBluef6]

First, had battery tested and it is fine.  Check that off the list.

It sounds like it is running out of gas.   She never runs rough and never pops.

I took the Pingle out twice to check the filter screen over the last few weeks. It is perfectly clean.  I do have a Golan fuel filter.  The bike behaves the same with or without the filter installed.  The fuel filter is perfectly clean.  The bowls have been perfectly clean.  I guess i did one heck of a good job cleaning out the gas tank.

I also blew air into the Pingle when i had it out to make sure the valve was acting correctly in the "ON" , "RESERVE", and "OFF" positions.  Everything was fine.

Yes the vent hoses are still installed.  I have not checked for blockage.  Will do. Good call for something easy to check. That falls within the scope of what i touched while servicing carbs which means i could have mucked it up.  But on several occassions while doing some test runs, i immediately turn off the Pingle when she dies and there is fuel in all 6 carbs.  But i will certainly check the vent tubes.  

UPDATE:  I blew air through the vent tubes are clear.  The only way i'll know if the air rails going back towards the carbs are clear is if i take them apart again.  We'll save that for a last resort.

[BigBluef6]

I am seeing a pattern in my test runs.  She will sit there all day and idle because she is not hitting the mains.  When i move down the street, i eventually move fast enough to hit the mains and she dies because i must have missed something in the cleaning.  I think she basically had a heart attack and i need to do some vascular surgery on her. 

Mr. Rodent from the attic in Tulsa, i found some places locally that sell the reamers.  I just have to find the Berrymans and will be taking her apart again, hopefully this weekend and hopefully for the last time.

I'll post the results of the operation to let you all know if the patient lived and what i did.  Stay tuned.... 

[sugerbear]

did you check the float level from clymers and honda manual? maybe a typo in clymers.

i heard there were some in the honda manual.

[salty1]

If you take your carbs apart again, you might trty sonication of all your jets in pine sol. Very interesting post. Thanks for your detail on the problem and measures taken to solve it.

[98valk]

I am seeing a pattern in my test runs.  She will sit there all day and idle because she is not hitting the mains.  When i move down the street, i eventually move fast enough to hit the mains and she dies because i must have missed something in the cleaning.  I think she basically had a heart attack and i need to do some vascular surgery on her. 

Mr. Rodent from the attic in Tulsa, i found some places locally that sell the reamers.  I just have to find the Berrymans and will be taking her apart again, hopefully this weekend and hopefully for the last time.

I'll post the results of the operation to let you all know if the patient lived and what i did.  Stay tuned.... 

the needles are in the mains, so essentially from 1/4 - 3/4 throttle u are using the mains restricted by the needles, 3/4 - WOT is all mains. idle is pilot jets, 1/8 -1/4 throttle is PJs, all circuits overlap and effect each somewhat through full throttle range.
if u are using a stock air box and filter and stock 100 mains it shouldn't be running out of gas. K&N might make it run lean but it won't stumble and fall flat.
suggest go back to baseline, no fuel filter in the line. check tank vent line also.
something else to look into the ignition sensors for the trigger wheel, they can cause a weak spark if the measured gap is too large or if they are starting to fail.

[BigBluef6]

did you check the float level from clymers and honda manual? maybe a typo in clymers.

i heard there were some in the honda manual.

The float height is fixed an not adjustable, although i think some have tried several ways to do so with varying degrees of success.  The height is set by the spring in the fuel valve.  They wear out at different rates.  But all my fuel valves (which determine float height) are all brand new with very close float heights. 

[BigBluef6]

I am seeing a pattern in my test runs.  She will sit there all day and idle because she is not hitting the mains.  When i move down the street, i eventually move fast enough to hit the mains and she dies because i must have missed something in the cleaning.  I think she basically had a heart attack and i need to do some vascular surgery on her. 

Mr. Rodent from the attic in Tulsa, i found some places locally that sell the reamers.  I just have to find the Berrymans and will be taking her apart again, hopefully this weekend and hopefully for the last time.

I'll post the results of the operation to let you all know if the patient lived and what i did.  Stay tuned.... 

the needles are in the mains, so essentially from 1/4 - 3/4 throttle u are using the mains restricted by the needles, 3/4 - WOT is all mains. idle is pilot jets, 1/8 -1/4 throttle is PJs, all circuits overlap and effect each somewhat through full throttle range.
if u are using a stock air box and filter and stock 100 mains it shouldn't be running out of gas. K&N might make it run lean but it won't stumble and fall flat.
suggest go back to baseline, no fuel filter in the line. check tank vent line also.
something else to look into the ignition sensors for the trigger wheel, they can cause a weak spark if the measured gap is too large or if they are starting to fail.

I remember seeing an excellent graphic of what you describe about the how the various fuel sources in the carb overlap, but of course i can't find it now to attached to the thread.    

I agree about going back to baseline, but i am going all the way back to breaking down the carbs again to see if i missed something.  It is a real PITA, but i guess i signed up for this back in 2001 when i bought her.   I am going to use a different method to clean the carbs than i did the first time.  The first time i used brake cleaner in a can and shot about a full can through the various carb passages.  This time i am going to get a K&L carb clean kit with various size reamer made to clean out the  internal passages beyond where we can see.  I am also going to soak them for several hours in something called "Berryman Chem-Dip Carburetor and Parts Cleaner instead of exclusively using brake cleaner shot from a can.   I talked to a guy offline that sounded like he knew what he was talking about and he recommended this method.  It is definitely a more intensive cleaning than what i did the first time.   I got the weekend free.  Lets see what i can come up with.

[98valk]

http://faq.f650.com/FAQs/CarbMiscFAQ.htm#Flat spot in carburetion

cv carb sites posted by madmike
http://www.valkyrieforum.com/bbs/index.php/topic,25236.0.html

[BigBluef6]

Over the weekend i got the carbs cleaned.  I soaked them in Berryman Chem-Dip Carburetor & Parts Cleaner for 3 hours http://www.berrymanproducts.com//Portals/0/images/0996.jpg.   Then sprayed about a can of carb cleaner through each carb through every hole i could find.  They looked just about brand new.  I also tested the 6 air cutoff valves (the question that started this thread ).  All 6 cut off at 15 on the Mity Vac as they should.

Put the carbs back on the bike, started it and it sounded great, much better than before the cleaning.  It was well worth the effort to clean them correctly.  Ran fine around the block at 20 MPH.
 Jumped on it to WOT and it died like somebody hit the kill switch.    Thinking vacuum diaphragms not pulling the needle out of the main.  I have to check the diaphragms.  I'll probably fill them with water.   I'm too ticked off to go near it for a few days.

The good news is that i found the carb diagrams i was talking about in an earlier post.  Look about 3/4 down the page for an excellent diagram of what is supplying fuel at different throttle positions.

http://www.iwt.com.au/mikunicarb.htm

CA, thanks for the other carb links.  Good stuff.

[whitestroke]

Very cool BigBlue



Carburetor troubleshooting is simple once the basic principles are known. The first step is to find where the engine is running poorly,  It must be remembered that carburetor jetting is determined by the throttle position, not engine speed. If the engine is having troubles at low rpm (idle to 1/4 throttle), the pilot system or slide valve is the likely problem. If the engine has problems between 1/4 and 3/4 throttle, the jet needle and needle jet (most likely the jet needle) is likely the problem. If the engine is running poorly at 3/4 to full throttle, the main jet is the likely problem.



While jetting carburetors, place a piece of tape on the throttle housing. Place another piece of tape on the throttle grip and draw a line (while the throttle is at idle) straight across from one piece of tape to the other. When these two lines are lined up, the engine will be idling. Now open the throttle to full throttle and draw another line directly across from it on the throttle housing. At this point, there should be two lines on the throttle housing, and one on the throttle grip. Now find the half-way point between both of the lines on the throttle housing. Make a mark and this will show when the throttle is at half throttle. Divide the spaces up even again until idle, 1/4, 1/2, 3/4, and full throttle positions are known. These lines will be used to quickly find the exact throttle opening while jetting.

[BigBluef6]

Very cool BigBlue



Carburetor troubleshooting is simple once the basic principles are known. The first step is to find where the engine is running poorly,  It must be remembered that carburetor jetting is determined by the throttle position, not engine speed. If the engine is having troubles at low rpm (idle to 1/4 throttle), the pilot system or slide valve is the likely problem. If the engine has problems between 1/4 and 3/4 throttle, the jet needle and needle jet (most likely the jet needle) is likely the problem. If the engine is running poorly at 3/4 to full throttle, the main jet is the likely problem.



While jetting carburetors, place a piece of tape on the throttle housing. Place another piece of tape on the throttle grip and draw a line (while the throttle is at idle) straight across from one piece of tape to the other. When these two lines are lined up, the engine will be idling. Now open the throttle to full throttle and draw another line directly across from it on the throttle housing. At this point, there should be two lines on the throttle housing, and one on the throttle grip. Now find the half-way point between both of the lines on the throttle housing. Make a mark and this will show when the throttle is at half throttle. Divide the spaces up even again until idle, 1/4, 1/2, 3/4, and full throttle positions are known. These lines will be used to quickly find the exact throttle opening while jetting.

Cool!  I'm glad you got the picture to display in the thread.  I think that one little picture will help  bunch of people understand carbs better like it did for me.  After cleaning my carbs for the second time  , my zero to 1/4 throttle improved dramatically.  I can now cruise around the neighborhood at 20 MPH (around 1/8 throttle) all day long.  My problems continue when i either jump on it or do a roll-on in first gear when i hit about 1/2 throttle.  The bike just dies like i hit the kill switch.  I know for a fact that both jets and the pilot are clean, but there still could be issues in the internal passages related to those jets that i cannot see.  The interesting thing is that the bike runs very smooth until it cuts off.  It never pops or backfires.  Very frustrating. 

[GreenLantern57]

Have you checked for Fuel line pinched or collapsed? Also, some that add extras in the fuel delivery have seen dying bikes when some of the fuel line falls below a certian level.  If you had those in place before this and it worked OK , then you could still have a collapsed line.  Enough fuel to idle, but not enough at speed.

[BlueValk]

"My problems continue when i either jump on it or do a roll-on in first gear when i hit about 1/2 throttle.  The bike just dies like i hit the kill switch."

I took off the top of my air box to experiment, and the bike acted exactly like you just described.  It was a real surprise to jump on the throttle and have the bike just die out.  It ran fine at partial throttle.

Maybe check and see if you have an air box modification ...

BlueValk

[BigBluef6]

Have you checked for Fuel line pinched or collapsed? Also, some that add extras in the fuel delivery have seen dying bikes when some of the fuel line falls below a certian level.  If you had those in place before this and it worked OK , then you could still have a collapsed line.  Enough fuel to idle, but not enough at speed.

To help avoid this, i went with the OEM fuel line.  That stuff is pretty stout.  I can grab the fuel line at the gas tank and see it moving freely all the way to the fuel rails, so no pinchy.

[BigBluef6]

"My problems continue when i either jump on it or do a roll-on in first gear when i hit about 1/2 throttle.  The bike just dies like i hit the kill switch."

I took off the top of my air box to experiment, and the bike acted exactly like you just described.  It was a real surprise to jump on the throttle and have the bike just die out.  It ran fine at partial throttle.

Maybe check and see if you have an air box modification ...

BlueValk

I have heard the exact same thing from several people.  An air leak it the theory i am working on now.  But i would guess it would have to be a pretty good size leak to kill her clean like it is.  When you did your experiment, did she pop and backfire?  Mine is not popping or backfiring at all.   I have a stock air box.  In fact, everything from the air box, through the engine and out the pipes is stock. 

I did a desmog to get rid of a huge amount of potential leaks.  I punched in 4 freeze plugs on top (size 14.4 mm) and made up a couple of aluminum plates for the bottom 2 holes and used some copper gasket maker to seal the plates.   Also plugged the hole in the air box that is left open after a desmog.   

This weekend, I am going to her pull apart and closely examine all the potential points of air seal failure from the air box through to where the intakes meet the head.   I'm going to double check the the bottom 2 desmog plates and the air box plug too.