TRX alum. airbox on ATC 250r w/pics

[dansvan]

Hello all. I wanted to try and improve my air flow to the carb on my 85 250r. Never liked the 90 degree turn and the bumps in the rubber connecting tube. So I purchased an aluminum airbox for a TRX. I was able to get it installed with lots of little mods. A little grinding here, bracket removal there, turn the shock around, relocate the shock res. etc. Heres some pics.

We've all seen the stock set up.
http://www.supermotors.net/getfile/618954/fullsize/p1010778.jpg


Here's the TRX box installed. The rear mounts to the seat latch bolt. I had to taper the front mount of the box slightly. I ended up removing the factory air box mounts. I also remove the rear little cross bar the green wire grounds on. There are little notches in the box here and there.
http://www.supermotors.net/getfile/618945/fullsize/p1010085.jpg

From the front. Also shock has been turned 180 for hose clearance. Res. mounting bracket gone.
http://www.supermotors.net/getfile/618946/fullsize/p1010086.jpg

Carbs. view.
http://www.supermotors.net/getfile/618947/fullsize/p1010087.jpg

Most time consuming part. I started with a piece of 2.5 inch and a piece of 4 inch exhaust pipe. I slid the 2.5 in and marked it. Then I cut slots in the 4 inch and started pounding and shaping. Along with cutting,grinding, and welding. It turned out pretty good. Pic is in the early stages.
http://www.supermotors.net/getfile/618944/fullsize/p1010084.jpg

Done. Everything hooked up except a shock res. clamp missing in this pic.
http://www.supermotors.net/getfile/618948/fullsize/p1010138.jpg

I used cheap silicone tube from ebay to hook the pieces together.
http://www.supermotors.net/getfile/618949/fullsize/p1010139.jpg

http://www.supermotors.net/getfile/618950/fullsize/p1010140.jpg

Need to get a TRX sized filter next.
http://www.supermotors.net/getfile/618951/fullsize/p1010141.jpg

http://www.supermotors.net/getfile/618952/fullsize/p1010142.jpg

Underneath view.
http://www.supermotors.net/getfile/618953/fullsize/p1010143.jpg

All for now. Time to go ride.

[Gdkarma]

Cool! :headbang: :headbang: :headbang:

I was going to try and make one for the 350X next week, just for the fun of it.:duck:

[dan_badgley]

Sweet.. I am wondering if this idea could be used on a 85 200X?? any suggestions I love what you done.. looks killa and I am sure it helps.

[Red Rider]

Dansvan, looks good. Will the swingarm hit the airbox if it bottoms out? It doesn't look like the TRX airbox has those dimples in the bottom of it for suspension clearance.

[dansvan]

I thought about that. I am a fairly heavy rider and rode it quite a bit this weekend. Never touched. But I didn't jump it much either. I was thinking you could cut out a square in the bottom of the TRX box and cut out the dimple on the ATC box and rivet it to the TRX box. If done right it would look very clean.

[Red Rider]

It would suck to have the swingarm bash in your shiney new airbox. If you're worried about it, you could always test it by removing the shock spring, bolt the shock back up, and running the suspension through it's arc. I destroyed a silencer once, because I didn't have it spaced out from the frame properly, and the rear brake caliper would hit it upon landing from big air. :doh:

[Red Rider]

Also, in your 5th pic, the piece of 4" exhaust pipe with all the slices in it, is that the airbox-to-carb boot? It looks almost identical to a TRX carb boot. Did you try to use a stock TRX rubber boot before making your own?

[dansvan]

I did. I purchased a hi-flow boot from AC Racing. Also tried a stock boot. Both hit the frame and would not line up with the air box opening.

[Duner]

If you wanted more air, why did you not purchase the air box elminator kit from ESR or fab yourself up one. The box itself hurts air flow. Run an outwear......looks nice, but it did not accomplish your orginal thought of additional air flow. My .02

http://www.eddie-sanders-racing.com/oscmax/product_info.php?cPath=5_42_46&products_id=32

[Black Sheep]

The box itself hurts air flow.


untrue. airboxes store air. the only time this is true is if your running an extremely large big bore/carb/air filter set up. then a stock airbox will hurt. in this case a larger airbox should be built.




......looks nice, but it did not accomplish your orginal thought of additional air flow. My .02


actually it did an excellent job of increasing air flow. this is the same type setup team Honda used on thier Factory 85/86 ATC 250R's.

the original boot makes a 90* turn off the air filter before going to the carb. this setup is a straight shot.


FYI when it comes to water or air traveling through any type of tubing/pipe, bends increase resistance

a 45* bend is = to 5' of straight pipe

a 90* bend is = t0 10' of straight pipe

[dansvan]

Couple of things. If the factory race teams used and still use airboxes then there must be some validity to running one. There is a long thread on here about airbox vs. no airbox. I ride in Alaska. Not much for dunes around here. Mostly dirt/water/muddy/gravel. etc. I like the protection from the box. I was even thinking of maybe "porting" my rear fender to supply a bit of air from behind the seat. Will I see a difference? probably not. but it might be another conversation starter.

No airbox will often dyno more. Why? Still air to draw from. Now go get the bike up to speed and that nice calm airflow is gone. There may even be a negative pressure in areas under the seat. Add an airbox and you get your calm air back.

[dovesprings250R]

Nice work! I have the ct alloy airbox on mine with a similar set up to the trx set up you used.

[NOS_350X]

No airbox will often dyno more. Why? Still air to draw from. Now go get the bike up to speed and that nice calm airflow is gone. There may even be a negative pressure in areas under the seat. Add an airbox and you get your calm air back.

If your dyno guy isnt blowing some fans twards the bike then hes just waiting to overheat a bike. I personaly have never see a dyno run without the owner of the dyno turning fans onto the bikes.

Mr atc How do you come up with the numbers for the bends?? just courious,

I would think it depends on how its bent, think about it if the bend is nice 45* like a ) then thats going to keep decent airflow, compared to something like 45* >. im courius how that would come into affect.

[Duner]

untrue. airboxes store air. the only time this is true is if your running an extremely large big bore/carb/air filter set up. then a stock airbox will hurt. in this case a larger airbox should be built.





actually it did an excellent job of increasing air flow. this is the same type setup team Honda used on thier Factory 85/86 ATC 250R's.

the original boot makes a 90* turn off the air filter before going to the carb. this setup is a straight shot.


FYI when it comes to water or air traveling through any type of tubing/pipe, bends increase resistance

a 45* bend is = to 5' of straight pipe

a 90* bend is = t0 10' of straight pipe

Old school tech meets new technology. Air box stores air..course they do, but they also prevent air flow. Does not matter what size box is there, its preventing air flow, even on the 86-87 TRX's, they have a ram air addition to their box...wonder if team honda realized they missed something on the trikes, so they added "additional" sourse of air flow...Even then, it does not compare to real world air being forced from all directions rather then storing.

[dansvan]

This is not my main argument, but thats why you see so many open element air filters on all the show room new bikes, quads, cars, trucks, etc. All those engineers that get paid incredible amounts of many are screwing everyone out of lots of horse power. If it sounds faster it must be faster right?

So in your idea if I were to put a vacuum nipple on my air box and hook my guage to it, it would have a negative reading? Because I used all the air in the airbox? If it stops all the pressure from all directions it shouldn't run, right?

In any form of motorsports, where the engine is required to run longer than a 30 second burst, you will fine well made and well tuned airbox sysyems. From the desert to the street to the race track. If shaving weight is all important and they still leave it on, it must do something right? If the engine made substantially more power without one they'd leave it off right?

Do a study on airflow dynamics sometime. That really is the bottom line. simple physics.

[firefirefire90]

SHUT UP!!!


I don't want to have to deal with another stupid airbox argument! YOU TWO ARE CHILDREN! Dayumn!

Cool looking airbox dude! Don't let tohse fools get in your head. They will never agree on anything.

Once they do, they are no longer fools. Nuff said.


PLUS, those silicone tubes look TRICK! Reminds me of the silicone tubing used for turbo parts and all that.

:headbang: :headbang: :headbang:

[dansvan]

I agree. I'm comfortable in my box.

[Duner]

SHUT UP!!!


I don't want to have to deal with another stupid airbox argument! YOU TWO ARE CHILDREN! Dayumn!

Cool looking airbox dude! Don't let tohse fools get in your head. They will never agree on anything.

Once they do, they are no longer fools. Nuff said.


PLUS, those silicone tubes look TRICK! Reminds me of the silicone tubing used for turbo parts and all that.

:headbang: :headbang: :headbang:


to quote the wise 250R messiah, "I don't even know why I try explaining this stuff"...

[84honda200s]

dude thats one sick box !! :hail: :hail: :headbang: :headbang: and to those that dont like it... tell em to kiss your :booty: !!!!!! :duck:




but really man that thing looks great. very nicely done.