** Note: This mod is only applicable to 96-99 gsxr750's and 96-00 gsxr600's **

ok so here are pics of my modded '98 airbox. the midrange and top end rush on the bike is ridiculous now, you can really tell it sounds a tad deeper and that its breathing in more air. from my seat-of-the-pants analysis, and wheelieability analysis, from 6K on up it is just an unbelieveable rush.

I recommend this mod to all 98-99 gsxr750's, as the PC or an FI remap is easy to do. I have heard the carbed gixxers are a biatch to jet properly. I dont know so I can't tell you firsthand. Do this at your own risk, but for the EFI SRAD's its simple to smooth out the fuel map. I had to lean mine out down low (below 5K) and richen most everywhere above that.

anyways, here are instructions and a picture of my airbox. notice the actuator valve rod is still in there, but there is no flapper.

Accomplishment Instructions:
1) remove the drivers seat (2 bolts).

2) remove gas tank bolts by steering head(2). lift gas tank, prop open.

3) remove all connections to airbox. there is one green electrical connector on the right side, one black electrical connector on the left rear side. disconnect the crankscase breather hose from the rear of the airbox, and the PAIR hose from the right side. loosen the two throttle body clamp screws. remove the bolt by the steering head that secures the airbox.

4) lift the airbox up a little bit and underneath the airbox is one more vaccuum hose. disconnect it and the airbox should be free. take the airbox off the bike and take it to a workbench/workcenter/etc.

5) remove the 4 screws to the top of the airbox and remove the air filter. set aside and while you're at it blow it out with compressed air - or if it's a K&N wash it and re-oil it. might as well while you're in there.

6) look underneath where the filter sits. notice the oval plastic ring around where the filter is seated. put your fingers into the square shaped hole/tower where the flapper valve is. notice the metal actuator rod that controls the flapper. feel the rear side underneath and you will feel a ridge that occurs foward of the oval. notice in the below picture how the rear part of the oval is not cut out. this is due to that ridge, make sure you are aware of it and do not cut through this part. my cut came fairly close to this ridge, altohugh it could be closer.

7) I used a Dremel tool with a cutting-type drill bit. anything you can use which is easy to move around inside the airbox will work. I suggest using a Dremel (or equivalent tool - Ryobi, etc). cut around just inside the oval on the sides and front. feel out the rear side and cut as close as you can to the underlying ridge. you will completely remove the square-shaped raised inlet, and you will have to cut through the hinges for the flapper valve. do not worry about messing up anything related with the flapper - its being ditched anyways.

8) after cutting away all the plastic, you should be able to lift out the cut piece and say goodbye to the flapper valve. the edge was rough and had lots of plastic burrs so I used the Dremel to sand the edge smooth. notice the size difference between the inlet you had and what you have now. it should be like over 2 times larger!!! Reference my picture below and you should have something like it.

9) the cutting and sanding threw tons of plastic gunk in the airbox. I hosed it out and wiped it with paper towels so it was clean and dry, free from all plastic gunk and grime.

10) *OPTIONAL* I also snipped the metal actuator rod for the flapper. you can leave this untouched since basically the valve would still function but there is no flapper for it to operate. I plugged the vaccuum hose that lead to this valve since it basically wasn't doing anything, but its not necessary.

11) the install your airbox back simply seat the airbox on the throttle bodies and connect the hoses and electrical connectors back onto the airbox, and tighten the TB clamp screws. replace the air filter and top. lower the tank and replace the drivers seat. voila! now ride the bike and see how it feels and remap/rejet as necessary.

** OPTIONAL **
A while back, I removed the PAIR system and installed the Intuitive Racing block-off plates. So this means that I plugged the PAIR hose into the airbox (3/8" plug fits nicely, you can get these from an auto parts store). Recently, I also plugged the crankcase breather hose inlet to the airbox (once again 3/8" fits nicely). I bought a Puralator AB23124 breather filter and connected it to the crankcse breather hose. Then I zip-tied the filter underneath the #1 fuel injector. Supposedly the bike will smell oily when it gets hot since dirty oily air is coming out since its a breather filter, but I haven't noticed much.

http://www.gixxer.com/articles/airbox_mod.jpg

[ 10-11-2001: Message edited by: admin ]

Thanx for the info JP. I did this mod on my 98 750 along with the R1 throttle tube and she runs amazing. Used the TEKA to reprogram the fuel map. Thanx again:cheers

Since the origional picture is no longer available and I have my airbox out for maintenance I figured I'd snap a pic of the airbox mod on my bike. If you follow the instructions listed above the end result should look like this, mind you a better job could be done but I ran out of sand bits for my dremel.

http://img149.imageshack.us/img149/2405/dscn30493oe.jpg

hope this helps anyone that needs visuals to work.

thanks!

Intressting modification. (sorry for reacting in an old thread)

Are there more pics online how the job should be done???
I see the way to disengage all kinds of things but maybe someone has some photo's of the job too??

My mechanic did this to my bike a while back, and I have had Idle problems ever since... any tips to get it to work correctly?

just did mine :thumbup no like literally - just did it lol 9:48 at night

http://media.photobucket.com/image/srad%20air%20box/scarface1942/IMG_0121.jpg

unmolested airbox

i have a moded one i may put back on to try now that i have some issues resolved.

I have SRAD 600 98 (33E) and after placing a KN filter, with a main jet 140/137,5 (that made very good results -it realy pulls from 10000 to redline in 6th), i started to make this airbox mod. i opened the hole as in the image above or like that. i should say that i have an extra airbox :).
steps of the process:
- open the hole in the airbox and place a short V stacks -> has it was expected, from 5000 to 9000 it seemed like a stumbling train, from 5k .
- adjusting the needle clip position, from 3rd to 5th notch (still with the extra washer) -> it got better, but still with air holes by 7000 rpm.
- deactivating the solenoides and replace the long red V stacks (trying to stabilise the air flow) - it got better (already in an acceptable state), but still feeling a poor mixture in all ranges, specialy in 2k-3k and 7k-10k rpm.

point of the situation:
- at this moment it seems to me that the main jet sill has to enlarge to 145/142,5 because the top end is a litle far of the best.
- about the hesitating about 7k i am a litle confuse. i think i should change the slide spring force constant, as i know that now there are other vacuum efects in the venturi and more air geting quicker to this point of the carb. (i confess that i don't completely understand the air dinamic of this part of the system), so i will gradualy increase the spring force to see the diference (this is a very important fenomenon).
- about the pilot jet, and the float level, maybe should be better to increse the pilot jet and/or the pilot air jet simultaneiously (pilot jet->12,5 to 15 and pilot air jet->135 to 140 ). at this moment there is serious hesitating problem at about 2000 -3000, althought it responds very well from 3k to 5/6k rmp.
- about the starting and idling it is still in good work without mods (3 and 2 3/4 turns).

Questions:
about the needles - i'd like to know if it is worth to buy a dynojet kit just to change the needles, or if that needles are really the best for this mod. even if i wanted to place ones chosen by me, i don't find no one that shows the specific dimensions of what they sell - just the tecnical base information. what tha f...
about thealternative S71 best kit from Factory, do anybody knows what are the machinings to the carb that they refer? i really am curious about that. by the way it seems that the S71 kit come with new springs, so i assume that this is also a very important mod to make, because it reflets the way the vacuum efect creates variable venturi.
link to clarify this -> http://www.drpiston.com/Cvcarbs.html

By the way, i know that there are litle diferences between the calif model and the others,like the pilot air jet for example (calif->135;others->140), and i'd like to hear some opinions about that and how it limitates the power.
i know that it's not easy to get this mod finnely tunned because it needs extra needles , jets , airbox, and a great dose of patience in a very complex system where the intuition is the key, and the numbers are always missing. so i'm sharing this experience, and i'd like to know your opinions in specific implementations. i'll try to post some picures next time, althought it will not show nothing special that i did'nt already said.

good mods :)

I know I am res-erecting an old thread, but has anyone done this to great affect on a carbed model without issues?

NO!!!

Cheers Armi... I thought after reading Baaaadddcats post that it might be an issue... Oh the joys of Carbs...