KTM Forums: KTM Motorcycle Forum - View Single Post - Duke 4 complete airbox delete project, success!
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post #1 of (permalink) Old 04-09-2016, 02:46 AM Thread Starter
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Join Date: May 2015
Posts: 392
Duke 4 complete airbox delete project, success!

Hey all,

I thought I'd start a thread about the mod I have been working on, mostly to get people's thoughts and feedback.

After taking the airbox out to do a SAS/Charcoal delete I realized what a huge and heavy unit it is, so I thought I'd see if I could follow in the SMC guys' footsteps and come up with a way to delete the airbox altogether and fit a pod filter.

I doubt there is any power to be gained from this, as the stock box is tuned for the motor and flows tons of air. It was just for fun, and because I think the bike looks real nice with open air where the airbox used to be.

One issue was that the stock rubber intake runner that goes from the airbox to the throttle body actually projects inside the airbox and trumpets out. The trumpet (velocity stack) helps smooth the air and increase its velocity, and the length of the runner is important as well, as it is tuned to work with intake air pulses (shorter runner=high rpm gains; longer runner=low rpm gains). I wasn't willing to lose the tuned nature of that runner, so I designed and 3D printed a velocity stack that keeps the same length and trumpet profile, but actually slightly enlarges the trumpet outer diameter for more air smoothing.

Here's the piece:



Unfortunately I don't have any pics yet of the bike fully put back together yet (still working on other mods), But here's some with it mocked up on the bike:



Anyway, that's about it. I'm pretty excited to get it all back together and start blasting around!

Last edited by Kafka; 04-09-2016 at 02:52 AM.
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