It's just to slow them down at idle. By shutting cyls off the
remaining
ones can run cooler piston temps because they can have a more normal
spark timing or in Yamaha's DFI case run a richer mix which is easier
to
reliably ignite & doesn't generate as much lean mixture piston heat
buildup.


Wouldnt the Optimax (or other DFI) the perfect setup to keep the
cylinders cool? You could easyly run it on 3 cylinders @ idle and lean
mode.

I would cycle the shutoff. So one rev 3 fire the next rev they pause
and the other 3 fire.

You would not have to inject any gas in the cylinders that pause and
could keep the motor a lot cooler.

I am not 100% sure how the optimax injectors work. It sort of has 2 per
cylinder, one for gas and one for air but if they operate seperately,
air could still be injected to cool the cylinder further.

Do you know why this isnt done?

Matt