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Modified Rx1 Airbox With Pictures

Sled Dog

Lifetime Member
Joined
Feb 22, 2004
Messages
5,669
Location
Saskatchewan
Modified my air box and ran it out on the same field same track same distance with the same clutching. Thanks Turk on the clutching you are truly a magician with clutching I spanked a sled that previously was spanking me ;)! . Ran with K&Ns on nice and dry and with my modified air box. What I found is virtually the same performance without the louder noise the K&Ns made. Ran all day yesterday with no problems of the air box freezing off like I was having with the K&N's. Will post more info once I test some more.
 

I checked the plugs today and all are a nice tan color while running 170 main jets. So I have the airbox open up enough and in the right places. I was in powdered feilds for 4 hours and the air box never iced up and still performs like the K&N's are on. So I guess the filters and prefilters are for sale. I also have the red holtzman springs but I dont need them as I have no hesitation the way it is right now with stock springs. This mod can make things a lot cheaper than going with filters as the main jets are cheap like borsht soup.
 
THIS IS WORKING FOR ME BUT AS WITH ANY MOD YOU DO SO AT YOUR OWN RISK!

(The bottom of the air box mod)

I cut eight inch and a quarter holes in the bottom of the air box six directly under the foam facing the carbs and you can see the battery through the holes. The other two are directly on the bottom and on each side of the air box under the foam by the smaller little foam pieces. Next I took out the rubber snout on the bottom of the air box and with a jigsaw and using the side edge of the stock hole as my guideline I cut right to each side of the air box making a nice round curve on each side. So in other words you are extending the stock hole to each side of the air box and rounding both sides. Use a file to make sure to clean off any loose plastic particle from the air box and blow clean with compressed air.


(The baffle above the foam)

The baffle now has a total of 14 inches of hole cut in it as well. This includes the holes there from the factory, 7 inches on each side of the baffle to keep air flow in balance. I got this measurement by measuring each holes diameter. Make sure to not hit anything on the inside of the baffle while picking your spots to cut with hole saw. Again use a file to clean your hole edge and blow clean with compressed air. Do yourself a favor and silicone your clamps in place so they dont move when you go to put your air box on. It sure makes it easy when the clamps are not moving on you.


(Carburetors)

Carbs are jetted with 170 mains and stock 04 springs. I had no hesitation so I seen no need to install the red CV Holzman springs.


(Clutching)

The Primary spring in my sled is a Y-S-Y and the weights are 8FA-17605-10-00 with both rivets installed. So my primary clutching is basically the same as a stock 05 Warrior and my secondary is stock 04 rx-1 mountain which is a white spring with 70 degrees twist. I am reving 10300 to 10500 WFO. So there you have it the complete mod that works and is cheap extra HP and top end. With this mod you should be able to hang with or beat the older Apex's with your RX-1

(Gearing)

My top gear was 21 tooth but is now 24 tooth and my bottom gear is still 40 tooth with a 70 link chain.

(Spark plugs)

Spark plugs are CR10EK and are running a nice tan color with my modded air box on.

(The hood vents)

I took them all off and installed them back on with womens black nylons to keep the snow from coming directly under the hood but still let air in for cooling.

This is running as good or better in performance than the K&Ns I had installed prior to modding the air box. When it comes to not freezing up the air box is much better than the K&N's even with the outerwear prefilters.

Enjoy!

I took pictures tonight and will post them later.
 

Attachments

  • Modded Air Box Bottom.jpg
    Modded Air Box Bottom.jpg
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  • Modded Air Box Baffle.jpg
    Modded Air Box Baffle.jpg
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  • Front vents covered wth womens black nylon.jpg
    Front vents covered wth womens black nylon.jpg
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I had been considering going with the red carb springs, have a stock set-up ('05 RX-1 Mtn). I ride at elevations of around 9K - 10.5K elevation in western Colorado. Let me know if you are wiling to part with yours.
 
Jerry said:
I had been considering going with the red carb springs, have a stock set-up ('05 RX-1 Mtn). I ride at elevations of around 9K - 10.5K elevation in western Colorado. Let me know if you are wiling to part with yours.

Would be wanting the K&N filters and prefilters as well?
 
I changed the stock phillips screw to an allan head on the airbox carb clamps. I got tired of the phillips slipping. The screw you need to replace them is a M4 with a .70 pitch 25mm long with an allen socket head. Much nicer with no slipping was nice to chuck the stock screws away where they belong in the garbage.
 
Have you been running without the top screen? seems to me as if it may be a bit restrictive, but then again I have been wrong many times before.
Thanks for loading the pictures, looks good...
 
04Brian said:
Have you been running without the top screen? seems to me as if it may be a bit restrictive, but then again I have been wrong many times before.
Thanks for loading the pictures, looks good...

I run the top screen you pretty much have too in order to hold the filter in place. You could cut holes in the screen if you wanted too but I really dont think there would be that much restriction unless it was iced up.
 
Hey SledDog,
I have had nothing but trouble with my K&N icing this weekend with 15-20cm of fresh fluff on the ground.

I have the stock box and would like to know what is the stock size jets? Do you have yours for sale?

I would ilike to do the mod but just not sure anymore on messing with this motor. I have 150MJ up to 165MJ but no 170's so either way I need jets.

Drop me a PM if you can hook me up with stock jets or let me know what the stock size is so I can order them in.

Thanks
 
Hey SledDog!

Nice Mod!

Just wondering if you know of anyone modifing an Apex airbox? I'm considering doing something similar to my airbox on my 07 Apex. But some people are saying that will screw up the sensors that run the Fuel Injection. Any thoughts or input?

Max ;):D
 


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