Air Box Mod/Bling


10 replies to this topic
  • BlueBeast400

Posted April 17, 2015 - 10:00 AM

#1

Just thought I would share my air box mod. I removed the snorkel, but also cut out a section right in front of that. I sheared a piece of perforated SS sheet to cover it so I get a little bit of protection from debris. Plus looks kinda cool.

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  • William1

Posted April 17, 2015 - 11:47 AM

#2

All that will do is make jetting more difficult. Stock opening with the snorkel removed is plenty large enough. Going larger only causes the vacuum signal at the needle to be weaker and therefore need a thinner needle to make up for less vacuum. Looks good but you'll never see it.....



  • BlueBeast400

Posted April 17, 2015 - 12:45 PM

#3

All that will do is make jetting more difficult. Stock opening with the snorkel removed is plenty large enough. Going larger only causes the vacuum signal at the needle to be weaker and therefore need a thinner needle to make up for less vacuum. Looks good but you'll never see it.....

 Whats the point of people removing the whole thing then??



  • William1

Posted April 17, 2015 - 01:56 PM

#4

 Whats the point of people removing the whole thing then??

The misconception that 'more is better'.

 

In truth, a strong vacuum signal at the carb permits more accurate jetting and operation. This has been proven by dyno runs and experimenting with air box opening size. A point comes where peak power no longer increases, that is the max air box opening size. Even then, only if you are only concerned about peak. Most are more interested in overall run-ability and may find a slightly smaller than max is best, again to provide the best possible vacuum signal. Removal of the air box screen on most bikes is a mistake too. An add-on that improves the vacuum signal are devices like the FMF Snap, Boysen power wing though they are completely unneeded if the air box opening is good and the jetting accurate. A 400 like yours needs no more than nine square inches of opening. That is a single opening and not nine, one inch holes  It is all about flow.



  • BlueBeast400

Posted April 17, 2015 - 02:23 PM

#5

Ok, just wondering cuz I've noticed some guys remove the whole lid all together and not just the snorkel.



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  • Babble

Posted April 18, 2015 - 11:34 AM

#6

I've recently bought a 2008 wr450. I've found that the snorkel and plate are missing.
I really have no interest in top end power, but do want to make the most of low and mid torque & rideability.
Is it perhaps worth me finding a snorkel to fit back in?
(If there are any uk members who have one, i'd be interested!)

  • stevethe

Posted April 18, 2015 - 11:57 AM

#7

I've recently bought a 2008 wr450. I've found that the snorkel and plate are missing.
I really have no interest in top end power, but do want to make the most of low and mid torque & rideability.
Is it perhaps worth me finding a snorkel to fit back in?
(If there are any uk members who have one, i'd be interested!)


No leave the binoculars off. Just make sure it has a jet kit installed.

  • Krannie McKranface

Posted April 18, 2015 - 04:54 PM

#8

All those perferations will only pass air at a certain velocity/volume, and will be rendered 'closed' above that

 

Good quality work.

 

Now rip it out.



  • stevethe

Posted April 19, 2015 - 04:50 AM

#9

Well um if you do rip it out you can re use it in front of your helmet to prevent bugs from entering into your teeth. :goofy:



  • offrd beatr

Posted April 19, 2015 - 06:41 AM

#10

Just run it. Tell me why MX bikes don't really have an airbox as much as they have vented side plates and a shield in front of the rear tire. The top is the seat. Performance engines require air and they don't care to breathe through a small hole.

  • Krannie McKranface

Posted April 19, 2015 - 02:58 PM

#11

The head on a WR motor is the choke point, not the airbox.

It's the exact opposite on a track bike, so the air box is wide open.

My WR is stage 3 ported with a YZ EX cam.,  so my box top is cut out all the way. 






 
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