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Author Topic: Drilling the airbox  (Read 3313 times)
SANDMAN5
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Posts: 2176


Mileage 65875

East TN


« on: September 23, 2009, 01:21:24 PM »

I was reading some ancient stories on the Valk and came across a line
that mentioned drilling holes in the airbox lid to get more air into the
engine....or at least to give it an easier entrance. Makes sense to me,
like flipping the breather on an older car. I don't remember anybody
mentioning this before. Was it a bad idea? Did anybody do it and end
up having trouble with water getting in? Anybody STILL doing it? I'm
thinking about giving  it a try. What size hole would be best? I'll also
put a small washer under the front of the tank, maybe 1/8 inch at most. cooldude
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Warlock
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Magnolia, Ms


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« Reply #1 on: September 23, 2009, 01:25:00 PM »

Most has found to leave it stock. Most had problems with it and ended up patching it back up. The easiest mod is to put a 1/2 spacer under the front and this allows more flow.
David
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98valk
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South Jersey


« Reply #2 on: September 23, 2009, 01:28:01 PM »

scroll down to my posts. U will need to re-jet and dyno tuning.

http://www.valkyrieforum.com/bbs/index.php/topic,8248.0.html
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Jess from VA
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No VA


« Reply #3 on: September 23, 2009, 01:28:07 PM »

Bob, I do not know from personal experience, but everything I've read leads me to believe it is a poor idea, with little to gain and much to screw up.  With all the gearheads around VRCC, why is this almost never discussed??   FWIW   If you are rejetted sufficiently, a K & N without prefilter will flow as well as you need. Some do this without rejetting, but I have read of unjettted Valks being leaned out because of no prefilter.
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Chrisj CMA
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Crestview (Panhandle) Florida


« Reply #4 on: September 23, 2009, 02:32:46 PM »

Most has found to leave it stock. Most had problems with it and ended up patching it back up. The easiest mod is to put a 1/2 spacer under the front and this allows more flow.
David

the spacer was to go under the front tank mount to raise the tank a bit not to raise the lid of the airbox
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The Purple Haze
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Proud Member # 23359 Purple '97 Std CSC Trike

Glendale, Arizona


« Reply #5 on: September 23, 2009, 04:56:11 PM »

the spacer was to go under the front tank mount to raise the tank a bit not to raise the lid of the airbox
 
I believe that is what he meant.  BigBF sells a great spacer for that purpose. http://bigbf.com/product_sale/
 
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Thunderbolt
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Worthington Springs FL.


« Reply #6 on: September 23, 2009, 05:50:20 PM »

I don't have any personal experience either, but it seems that all I ever read on it says it causes more trouble than it is worth.
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SANDMAN5
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Mileage 65875

East TN


« Reply #7 on: September 23, 2009, 05:58:33 PM »

OK, thanks, ya'll. I kinda figgered that's why it wasn't talked about a whole lot.
I'll still probably raise the front of the tank a little, but I'll leave the airbox alone.
The K&N is enough. Smiley
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Warlock
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Magnolia, Ms


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« Reply #8 on: September 23, 2009, 09:28:54 PM »

Most has found to leave it stock. Most had problems with it and ended up patching it back up. The easiest mod is to put a 1/2 spacer under the front and this allows more flow.
David

the spacer was to go under the front tank mount to raise the tank a bit not to raise the lid of the airbox
Forgot to say gas tank, but if you have pulled enough air boxes you'll realize a 1/2 spacer on the air box itself want work at all.
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FLAVALK
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Winter Springs, Florida


« Reply #9 on: September 24, 2009, 05:37:15 AM »

Most has found to leave it stock. Most had problems with it and ended up patching it back up. The easiest mod is to put a 1/2 spacer under the front and this allows more flow.
David

the spacer was to go under the front tank mount to raise the tank a bit not to raise the lid of the airbox

ACE hardware has a white nylon spacer 1' diameter x 1/2" thick with 3/16" hole that fits perfectly with no modification. A pack of two is less than $1. I painted mine black
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Ricky-D
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South Carolina midlands


« Reply #10 on: September 24, 2009, 08:23:50 AM »

I don't think that a gas tank spacer has any benefit whatsoever except maybe a psychological boost  uglystupid2 to the "seat of the pants dyno".

The reason I say this is the FACT  2funny  that the air intake is facing rearward on the airbox.

If you were to raise the rear of the gas tank it would make more sense.

 coolsmiley
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2000_Valkyrie_Interstate
Hellcat
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Arlington, VA


« Reply #11 on: September 24, 2009, 02:10:42 PM »

I don't think that a gas tank spacer has any benefit whatsoever except maybe a psychological boost  uglystupid2 to the "seat of the pants dyno".

The reason I say this is the FACT  2funny  that the air intake is facing rearward on the airbox.

If you were to raise the rear of the gas tank it would make more sense.

 coolsmiley

I don't know if it works or not, but the theory is not necessarily flawed. A bigger opening at the front of the gas tank would allow more air in, which would be forced between the top of the air box and the bottom of the gas tank at a higher pressure due to the larger difference of space front to rear.

Therefore more air would reach the reach the rear of the air box at higher pressure.

So the theory does in FACT  2funny make sense. Whether it works in practice I have no idea.

Now, on an Interstate with a full fairing, that hole doesn't take direct airflow, so the theory seems less useful.
« Last Edit: September 24, 2009, 02:13:28 PM by theopowers » Logged
Tundra
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2014 Valkyrie 1800

Seminole, Florida


« Reply #12 on: September 25, 2009, 06:46:26 AM »

I know two who have drilled/modified their airboxes. Both "repaired", patched, or taped the hole to go back to the stock box.
  
Want more air? Go K&N and remove your pre-filter...be done with it. Ifin you aren't thrilled with your results and fussin with your pilots to get it right, put it back in.
  Pre-filter, no pre-filter can be as contraversial as tires and oil. I run mine this way as many others, works for me cooldude With my headers and air filter I needed to richen it up a little.
« Last Edit: September 25, 2009, 06:50:14 AM by Tundra » Logged

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R J
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DS-0009 ...... # 173

Des Moines, IA


« Reply #13 on: September 25, 2009, 09:31:16 AM »

I don't think that a gas tank spacer has any benefit whatsoever except maybe a psychological boost  uglystupid2 to the "seat of the pants dyno".

The reason I say this is the FACT  2funny  that the air intake is facing rearward on the airbox.

If you were to raise the rear of the gas tank it would make more sense.

 coolsmiley

Hey Grasshopper, why you think this theory no work?

How many Camaro's have seen running around with the rear of their hood raised from the factory, or Doge Ram Hemi's with the same style hood?    Trust me Grasshopper, it works...........

PS: leave the firkin airbox alone, & don't ask how I know.
« Last Edit: September 25, 2009, 09:33:26 AM by R J » Logged

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Mikey
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Winona, MN


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« Reply #14 on: September 25, 2009, 09:38:48 AM »

Fact of the matter is that whenever you build pressure under the tank, it will help it breathe better. The back of the tank would decrease pressure under the tank (think of it like an airplane wing, if you will). If you wanted to get nuts with it, I suppose you could build a foam "dam" on the rear end of the airbox, and lift the front of the tank so that the air goes in and has more resistance to escape.
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Duey
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Rochester, MN


« Reply #15 on: September 25, 2009, 11:04:05 AM »

 coolsmiley
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R J
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DS-0009 ...... # 173

Des Moines, IA


« Reply #16 on: September 25, 2009, 12:48:39 PM »

coolsmiley

Give him a stoogie, he is correct.

The spacer is just a reverse of this, & should shove more air into the airbox.

I know MGM woke up a little bit when I did it.
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greggh
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OMAHA NE


« Reply #17 on: September 25, 2009, 01:05:56 PM »

The spacer is there to help give clearance between the tank and the Velocity stacks on the top of the carbs.
If you raise the tank this way, give thought to adding some extra rubber under the tank around the frame to help put support back to the bottom of the tank instead of having all the support of the tank rest soley on the font mounting flange.

The Weight of the tank and gas could cause a stress fracture on the front mounting unit.
Just my 2cents
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John U.
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Posts: 1085


Southern Delaware


« Reply #18 on: September 25, 2009, 05:05:34 PM »

The spacer is there to help give clearance between the tank and the Velocity stacks on the top of the carbs.
If you raise the tank this way, give thought to adding some extra rubber under the tank around the frame to help put support back to the bottom of the tank instead of having all the support of the tank rest soley on the font mounting flange.

The Weight of the tank and gas could cause a stress fracture on the front mounting unit.
Just my 2cents

I agree with your comment about tank support. Even though I was assured the tank would not wobble from lack of support at the frame rails, I figured those rubber pieces on the frame are there for a good reason. I found that short pieces of the hollow "noodles" the kids use in swimming pools did the trick very well. They can be easily trimmed to get the righ size and shape.
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R J
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DS-0009 ...... # 173

Des Moines, IA


« Reply #19 on: September 25, 2009, 06:25:35 PM »

They might have used the spacer for stacks on an I/S, but the Std/Tourer did not need a spacer to add stacks.

Littler  tank.   Ya put an I/S tank on any model w/stacks ya need the spacer.
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Udo
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Germany, Krefeld


« Reply #20 on: September 26, 2009, 06:09:32 AM »

I´ve added stacks to my Standard. Without a spacer it´s really close. I´ve added a spacer, maybe 3/8". Without the spacer there was room for just a sheet of paper, between the tank and the stacks.....
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