Re: 49cc vs. 66/80cc True or False?
There is an old automotive saying that holds true for motorized bicycles as well.
"The only substitute for cubic inches is, more cubic inches"
There may be claims that the smaller engine has advantages and well they might. Nevertheless, power is a product of how much force is applied to the piston and when the same power is applied to a bigger piston, more power is the result when compared to the smaller one. All things being equal, the larger displacement engine makes more power.
The key words here are "all things being equal". That is bike/rider weight, gearing, tire size, terrain and a host of other factores that must be taken into consideration when comparing smaller engines with bigger ones.
As for vibration; the lower the crankshaft RPM, the less the vibration. But again, "All things being equal" plays into that equation as well.
Age and Treachery Will Always Triumph
Over Youth and Skill & "Charlie Don't Ride"