Messin' with exhaust cams

[jumjum01]

I had spend a lot of time messin' around with different exhaust cams and cam timing on my 1397ccm gen1 hayabusa.

tryed out these 3 ex cams:
- Stock gen1 ex cam
- Aftermarket ex cam (same specs as intake cam)
- Gen3 ex cam

Stock ex cam has small lift and small duration.
Aftermarket cam has larger lift and larger duration.
Gen3 cam has huge lift and medium duration.

Here is what I have learned (at least on my bike);

- Bigger lift over stock ex cam lift makes no difference in HP
- Small valve overlap makes more HP from 0-6500rpm vs. larger valve overlap (+4 HP@4000rpm)
- Larger valve overlap makes more HP from 7500rpm and up vs. small valve overlap (+6 HP@9700rpm)
- Cam timing is a compromise, you can move a small amount of power up/down rpm scala, you cant get both
- Cams with larger durations kills low end power due to bigger valve overlap, but gains at top rpm

 

[bigoltool]

Stock valves, bowls, porting etc? Just looking for a little more context.

 

[jumjum01]

Stock valves, bowls, porting etc? Just looking for a little more context.

Head and valves are stock