Here are all the designs I tested.  I have ranked the designs in the order of performance by seat of the pants testing and airflow model testing.  1-5 utilize the stock tube whereas 6 utilized a shorter-than-stock-tube rubber 2.25" coupler adapter from a hardware store.  The initial Kamikaze design is not included since it's been evaluated thoroughly already.  The order of fab and testing are 2, 3, 6, 5, 4 and 1 being the final design.  


1. This one worked the best for several reasons.  First, it utilizes the stock tube that appears to be the best length and diameter which, as Verslagen pointed out, was designed that way for a reason.  It is the shortest of the six which means there is more airspace between the opening and the frame. The longer setups seem to be slightly affected airflow wise at higher rpm by the more cramped space between the opening and frame/wiring stuffed underneath the seat.  This design also has the honeycomb accelerator.  With it I noticed:
a) smoother idle.
b) my idle mixture screw adjustment/peak idle rpm was one full turn more out than the exact same setup without the honeycomb.  It is at 1.5 turns out now with a 55 pilot jet with bleeder holes.
c) the engine seemed to run super smooth from low to high rpm.
d) power and acceleration felt about the same as without it (it’s hard to tell).
e) while running at highway speed and pulling in the clutch when coming to a stop it came back to idle smoothly.  Before it would sometimes feel like it would drop below idle rpm for a moment then bounce back up to normal.  For instance, if idle is set at 1100 rpm, when cruising then pulling in the clutch, it used to feel like rpms dropped to say 900 for a second or two then return to idle.  Every once in a while my bike has stalled when this has happened.  Not often but when it did it was at this point of below idle rpm drop and cut off instead of bounced back.
f) the honeycomb filter is great support for holding the filter material in place without creating extra resistance such as the screened round metal piece I first used when I added internal filter support to the original Kamikaze intake. .  The honeycomb straws are 1.75 “ long.




2 and 3.  Number 2 was the next best design although 3 is essentially the exact same performance.  Number 2 is when I first experienced the true potential of a good intake design.  Why do I feel the number 1 design better?  The 1 to 1.25” longer overall length of 2 and 3 added a little bit more resistance at high rpm due to longer tube length that the air has to travel.  They also reduced the air space area between the opening and the frame as compared to 1.




4 and 5.  Number 4 inspired number 5.  Both worked great at low rpm.  At high rpm the larger opening/longer length showed me the importance of more air clearance between the intake opening and the frame/wires underneath the seat.  5 has about an inch longer larger opening area than 4.  Something interesting about number 5 that I think I forgot to mention in the previous posts.  Twice while cruising at 75mph with 5 installed, I got hit by a huge crosswind and each time the bike surged for moment.  I think this is because of the large opening and air reservoir between the rubber tube and the outside air.  The high air pressure of the gust combined with the different air pressures of the air reservoir and the tube created a momentary airflow disturbance.  With 1,2,3,4 and 6, I never experienced this with crosswind gusts that were even more powerful.  



6. This one just doesn't have the low and midrange power like the others even though it has more airflow area than all the other models.  Of all of the prototypes, it the one that felt most like having a pod filter on the bike at low to midrange,  Performance at higher rpm was better than a pod filter though.  Recall this is the prototype that had the hardware store rubber coupler that was shorter than the stock tube.  The stock tube also has a ¼” progressive narrowing from opening to carb mount which provides some additional air acceleration which a straight rubber tube would not.  Also, with this model, the air had to bend to get into the tube.  

The honeycomb was made from drinking straws from Krystals.  They are common size straws.  I say "common" because there are few fast food joints that use larger than common diameter straws but using them would require making the honeycomb another 1/2' longer.  The honeycomb length should be 6-8x longer than the diameter of the individual straws.  The honeycomb was made by cutting several pieces and applying some silicone to part of the outside of each straw using a small artist's brush and sticking them together.  I added 6 smaller straws on the outside for a snug fit.  To mount it in the PVC I slipped the honeycomb into the front opening about a third of the way in, put silicone on the outside of the honeycomb and then slid it in the rest of the way until flush. Clean off any excess silicone that may ooze out the front.   

Here's how I made the opening.  I used 2" PVC pipe for the housing and a 2" coupling for the outer ring.  Here they are before cutting.


Here is the final product.  The housing is narrowed to fit snug into the tube while the wider, un-narrowed portion of the 2" pipe fits snug into the enlarged opening that the clamp covers.  It will stay in fine without the clamp but I still use it to hold the filter on.  The outer ring is glued on with super glue.




The inside edge of the PVC is tapered so the air has a smooth transition from PVC to rubber tube.

Can you tubilator be applied to a stock air box?

I think that would be a good place for it.  I've seen some honeycomb around the shop.  Have to see if there is any left over.  

i tried a pvc adAPTer  a p trapp and it did have air flow problems at hiigh speed;

Would you be as so kind and list the items you used to make #1 and lengths, and where you could get them?  I have a good idea already on how I am going to go about this but others may not

And what you use to keep the "honeycomb" together?

saluteTOme wrote on 03/28/09 at 13:37:19:


saluteTOme wrote on 03/28/09 at 13:39:07:


Get these items:


Your tube, PVC opening with turbulator (optional), sponge filter (optional), K&N air filter oil, round gutter leaf strainer/guard, electrical tape, cheesecloth and scissors.  The optional sponge filter can be shaped and placed inside of the metal frame pictured below.  I'm more than happy without it.  The turbulator is optional.  The tube setup works very good without it.  It just that it works better with it.  I suggest you try the intake without it first then make one later if you want to.  To build the turbulator, I cut even length pieces of straws, dipped a brush in silicone, applied the silicone and stuck 2 straw pieces together, brushed and added another, and another, and so on.  Some have made a big deal about the straws coming out and getting sucked into the carb.  Whatever.  I trust my work.

Although I'm showing the steps of how my filter is set up, you could  use a pod filter on the end instead.  

I've improved my filter by doing the following:


And mount the intake to the carb:


You can also place a hose clamp on the end over the electrical tape, where the wire overlaps the tube.  

I'm thinking that in place of the PVC you could use one of those little piss pots they give you at the doctors. They have a thinner wall and a screw top.
I had an idea for filter material. My daughter has a tropical fish tank with a filter. The material used as the pre-filter would be excelent for this application as it is about half an inch thick and because it's in water all the time it's quite strong and stiff.
PS. Where did you put your battery?