"Clutch less system" doesn't mean it does not have a clutch. Its just that we don't have the lever.
Like in mopeds they use the "centrifugal clutch".So i guess the same moped mechanism will be used on JAIVE with obvious differences like the rear wheel will be driven by chain instead of belts like in mopeds.The tank & engine will be placed in a bike like position so that it can be called a bike.
How Centrifugal Clutch Works - In simple words & as the name says it works on the centrifugal force theory which is "outward force away from the center of rotation".
Image
So as you see in the above pic the (1)HUB is connected to the crankshaft of the engine.As you start the engine it starts rotating.
Now when you accelerate (raise the engine RPM) the "centrifugal force acts" i.e the (1)HUB rotates & forces the (2)FLY WEIGHT to go and attach to the (6)CLUTCH DRUM.
The (2)FLY WEIGHT cause the (6)CLUTCH DRUM to rotate which is connected to the rear wheel by belt in mopeds & i guess by chain in clutch less bikes.
Now when you leave the accelerator or brake & at certain RPM limit the (4)TENSION SPRINGS have force greater than the centrifugal force which bring back the (2)FLY WEIGHT to its original position & keep on rotating in that original position until the RPM raises again.