Quote:
Originally Posted by lammypie
engine braking is very little to do with friction in the gearbox and engine so no.. its more to do with it sucking air in,
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So what happens when exhaust valve opens?
IMO it is pumping losses from moving air in crankcase that gives engine braking as well as frictional losses. Sucking air losses are negligible.
As to which is better for mpg, it depends whether FI injects some fuel, some do this to make pickup smoother I believe. Not sure though. Ideally you'd find out by using a lambda sensor, maybe someone could have a look next time they're at a dyno.
However, considering the amount of gas flow is low, the mixture could be rich, and still not use much fuel in absolute terms.
And another point, how does using engine braking result in needing to replace gearboxes? I would suggest you learn to ride the bike properly...