[jkv45]

Originally Posted by DannoXYZ

Yeah, I think those giant jets are to make up for mid-range stumbles and cross-wind issues with pod-filters. But you end up leaving A LOT of high-end power on table due to excessive richness.

My sponsor Spears dyno-tuned my bike at beginning of 2017 season. We tried factory air-box with K&N filter and then pod-filters. Not single bit of difference! While airbox and filter may be restrictive on bigger bikes, for 248cc, they're simply HUGE! About same size as airbox & filter on my CBR600RR with 4x air-flow and 4x power! So freeing up airbox & filter doesn't do anything because the're not restricting anything. Most of restriction on intake-side is in head port-shape and cam-specs.

Exhaust on other hand, can really be improved. Using full exhaust with larger diameter tubing and free-flow straight-through muffler, we got 22% more air-flow and 22% more power. With stock jetting, it was still too rich. Downsizing to 96 Keihin mains brought AFR into more powerful ~12.0 range and gained another 0.5hp or so. Could've gone leaner to 94-95 mains but we didn't want to risk detonation on 110F+ days or getting bad batch of gas.

On street bike that would've been OK, but on race bikes, we want slightly larger safety-margin as it's WOT for 20-minutes at time in much more demanding conditions.

Ha - people just can't believe that either could be possible!

You mean a K&N filter, pods filters, or richer Main Jets don't give me 10 more HP?

What???