A self-balancing motorcycle with pure logic bricks.
Can cheat Akira style slide.
How to auto-balance a bike? Just hang a enough amount of weight below the ground level, very simple.
But this solution brings about unnatural behavior thanks to the law of inertia:
the bike nosedives when accelerating forward and wheelies when braking!!
To prevent this, I cunningly constrained the weight's Y and Z axes movement onto a static body which is parented to the bike's main body.
For more detail, please see "balancer" rigid body object configuration.