airbox cut out size

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kdxdazz
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airbox cut out size

Post by kdxdazz »

hi guys,new kdx owner and new to this forum. what is the optimum cut out size for the airbox with snorkle removed, i know through experience bigger is not better and i am interested in preserving torque as much as possible. my bike is 1999 kdx 220 with rb carb and head mod
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Re: airbox cut out size

Post by KDXGarage »

Welcome to kdxrider.net.
Thank you for participating on kdxrider.net. :bravo:
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Re: airbox cut out size

Post by B737driver »

Me personally, I cut the majority of it out...only leaving the frame and the area where the CDI attaches. No ill effects or other issues.

I'm certain that a search would turn up various ways that it's been done.
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Re: airbox cut out size

Post by Julien D »

Leave only what you need to for mounting CDI, or move the CDI and just remove the lid completely. Your choice. In this case bigger is better.
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airbox cut out size

Post by SS109 »

The KDX in stock form is very restricted as far as the air box is concerned. Just compare it to other 2T bikes in the 125 to 200cc range. I relocate the CDI and remove the lid completely. I have the same RB mods, along with removing the lid, and it hasn't hurt the torque of my 220.
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airbox cut out size

Post by kdxdazz »

thanks guys, my bike seems to run very rich and i wonder if the small airbox opening is a reason. i just welded in a bung to hook up my wideband O2 sensor. hopefully this will give me some direction
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Re: airbox cut out size

Post by KDXGarage »

Oh wow. Please let us know how it goes on the sensor, sounds exciting. :supz:

On the airbox lid, I am of the opinion that it is a water cover. No water, no need for a lid. Wet conditions? How wet? Partial lid needed or full lid and snorkel too?

On my 1994 KDX200, I have one modified lid that is basically a CDI holder and one that is full / normal.
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airbox cut out size

Post by cornishwrecker220 »

Unless your 220s motor has been breathed on then I personally wouldn't hack away at the lid .
Just remove the snorkel & drill x3 1 inch holes just below the snorkel lip , & fit 3 uni filter individual filers instead ...press them into the holes & secure with silicone sealant ..
I have fitted these & they work good & keep crud off your air filter .

The 220 isn't like the 200 as its power is designed for low to mid range power ...it has a narrow powerband & the power falls off quite sharp...you can adjust the timing to gain some over Rev , but in my opinion & experience the 220 in whatever state of tune runs better ,sounds better & is easier to jet with the air box lid in place , snorkel removed & a few holes added .
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Re: airbox cut out size

Post by kdxdazz »

sounds like sound advice thankyou. this bike will be a single track bike so top end horsepower is not important to me,i know the consensus is to make the lid as large as possible but i have experience with my drz400 and a bigbore scooter i modified and i know too large will reduce air velocity and therefore torque, one trick i did with the scooter was to remove the lid entirely,duct tape it up almost completely then remove slithers of duct tape until i found the optimum size.
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airbox cut out size

Post by cornishwrecker220 »

Google "uni filter air box vents"..... I bought mine off eBay for around £5 for a pack of 5 . :grin:
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airbox cut out size

Post by SS109 »

cornishwrecker220 wrote:Unless your 220s motor has been breathed on then I personally wouldn't hack away at the lid .
Just remove the snorkel & drill x3 1 inch holes just below the snorkel lip , & fit 3 uni filter individual filers instead ...press them into the holes & secure with silicone sealant ..
I have fitted these & they work good & keep crud off your air filter .
His has been "breathed on" with RB mods. If it has an RB bored out 35mm PWK, and a desert pipe to boot, then no lid is a benefit IMO.
cornishwrecker220 wrote:The 220 isn't like the 200 as its power is designed for low to mid range power ...it has a narrow powerband & the power falls off quite sharp...you can adjust the timing to gain some over Rev , but in my opinion & experience the 220 in whatever state of tune runs better ,sounds better & is easier to jet with the air box lid in place , snorkel removed & a few holes added .
Yes, it was designed that way but any engine can be changed/modified. My powerband is wider than stock with nothing more than easy mods anyone can do and no lid. My bike runs great, sounds great (although louder than stock), and is just as easy to jet as any other bike IMO/IME. The 220 can be made to move with the right parts and mine embarrasses some 300's and 450's out here in the singletrack.
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airbox cut out size

Post by cornishwrecker220 »

:lol:

Just because a head has been skimmed & squish measured, & carb bored then I don't personally see it as being "breathed on " as such although yes it's been altered from stock. ....I was referring to major porting, combined with other modifications to suit .
Yes head & carb work will increase a bikes performance but to get the best then it's a long journey of testing & money .. but we are talking about a 220 here & one in a soft state of tune...I'm talking from my own personal experience with my 220 & how after 9 years of ownership I have ended up with a great bike that performs very well indeed, now if this is going to turn into a pissing contest then how does 39.8 bhp measured at the rear wheel sound ...yes mine also will embarrass ktm 200s & most 250 4 strokes ...the guy just asked for advice & I just gave my opinion , wether he takes it is up to him...what works for one may not necessarily work for another .... But if he hacks away at the lid & doesn't like it then the lid is just junk.... Installing the uni air box individual filters means you can remove ( & tape up ) or install more if you so wish.
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airbox cut out size

Post by SS109 »

No pissing contest intended. I, also, was merely stating an opinion based off my personal experience with my 220 and and other bikes. My experiences run counter to yours and that's ok. Different bikes, sometimes different results. My point was that removing the unmodified lid completely is easy enough to do and it doesn't destroy anything. At any time it can easily be put back on if it were to hurt performance. No holes to drill or extra stuff to buy. It's real simple and free. Sorry I quoted you and you felt that it was a personal attack on your experience. It was not meant as such.
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airbox cut out size

Post by cornishwrecker220 »

It's fine buddy & I accept your statement ... Sometimes text can be miss interpreted so no offence was taken ....
Crack open a beer from me & raise a glass to the new year ....

Happy new year to all on here & hope everyone has a happy & healthy 2018 ! :grin: :partyman: :supz:
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airbox cut out size

Post by SS109 »

cornishwrecker220 wrote:It's fine buddy & I accept your statement ... Sometimes text can be miss interpreted so no offence was taken ....
Crack open a beer from me & raise a glass to the new year ....

Happy new year to all on here & hope everyone has a happy & healthy 2018 ! :grin: :partyman: :supz:
Cool! Happy New Year! No beer for me, though. I'll be doing my New year's day tradition of playing in the dirt on my KDX! :supz:
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