I have read various threads on fly removal, and I have to say I'm surprised at the myopic take on this from the various engineer types.
One thing constantly bantered about is the issue of air speed, comparisons with the zx14, what Kawasaki had in mind, etc etc.
Nobody has, to my reading, even raised the issue of cam timing, and more to the point, variable valve timing. Maybe because this is even voodoo to engineers not skilled with the effects of cam timing.
I could make various foolish comparisons like "flow from a garden hose and flow from a fire engine hose" but that's not realistic tuning. Nothing varies that much.
Instead, lets look at reality... the effects of cam overlap at lower engine rpms, in this case appx 5000 rpm and down.
The c-14 has shorter duration cams than the zx14, which mandates less overlap given consistent lobe centerlines between the two engines. VVT at low rpm is capable of removing, by my measurement, 20* of cam overlap at low rpm. This has a HUGE effect on intake dynamics. Passive egr / reversion is lessened or non existent. Higher intake air speed encountering an early closing intake valve helps build pressure in the intake track. Trapping that intake charge with computer controlled secondaries could potentially help create a stronger pressure wave upon the next intake stroke.
The zx14 has no vvt, and longer intake and exhaust cam timing. Much greater overlap, which any tuner knows is detrimental to low rpm power due to passive egr / reversion issues. With larger throttle bodies, it would be easy to see intake velocity could not overcome reversion effects, and volumetric efficiency would drop at lower engine rpms. In this case I think secondaries are the only reasonable response to gaining the most power potential at lower rpms.
Of course, the c-14 TB's are smaller than the zx's. Given this, and the velocity this alone would help create, the need for secondaries in the c-14 is lessened as compared to the zx14.
Couple that with the effects of shorter cam timing / vvt / decreased or non existent overlap, I could see a point where the c-14 could actually gain power by a very carefully tuned secondary fly, opening as much as possible to create ultimate volumetric efficiency but no more than that.
IMO, since there obviously power to be made by removing flies or reflashing the ecm, I think the obvious correct tuning procedure would be to have the flies controlled by the ECM, but with optimized opening to create the best cylinder filling at lower rpms. With this in mind, I feel this negates the argument that reflashes are only so someone can have "something to sell". Unless those proposing fly removal can support it's superiority over a proper secondary tune from the ECM, they are only GUESSING.
Think about it.
steve
