After much dyno time on StephenRC45's MC18 and some MC21's, 4x 20mm holes in the front slope of the airbox lid was been deemed the best solution for most road bikes.

It works better than any other modification, but he would still tape off two holes to richen it up a tad on a cold night leaving my place.

NO delimited NSR should make below 60hp (except an MC16) with the airbox modded like this. If it does, then it's on the way out.

Leaving the lid off tends to make them seem rather weak (limp, not lean!) -- you're better off with open carbs or a modified lid. Whatever you do it needs careful setting up, as once you start fiddling they become very sensitive to any changes.

Best part of 75hp on 98 pump unleaded out of his MC21 (without ram air) says who are we to argue with his results.
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Andy.
NSR-WORLD.COM

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