Getting more air

I've read that a few people have cut holes in their airboxes on the 520's. Would someone mind giving me the step-by-step including the necessary parts?

Has anyone modified the airbox on a 400, and if so, was the result noticeable?

Pull your airbox cover off while riding to see if it makes a difference.

Attention!!! DANGER! DANGER! DO NOT remove the air box cover while riding, it could result in a nasty fall. Besides the damn thing is hard enough to get off when the bike is stopped.


'01 520EXC, '74 YZ520, '71 TS400, '86 XR250.

If you cut vent holes in the air-bix cover, you have to go bigger on jets, right?! Wont that lean it out too much without jetting?

I still think people are too fussy on the jeting aspect. I can't believe it would make difference that anyone but Charmichael would notice.

Elevation here, 350 MSL, when I took my bike to CA, we rode as high as I think 4k, at Glen Helen, Elsinore, and Comp Park (at least 3500 MSL) She was a little harder to start, (2 kicks, not 1) and I got backfires when starting, and sometimes under decel....but I mean, it didn't make a difference. Unless you're top gear, WIDE OPEN the whole time....power shouldn't be a concern. My opinion.


'01 KTM 520 SX

'95 KX 250 FOR SALE!!! -asking $2000 with decent amount of plastics/decals, parts!!

AMA Dist 6 Member

Hare Scramble Class B #523

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