What everybody uses at the track here is an old scooter engine bolted to a wooden board on casters, and with a go-kart wheel and tyre on it. With the bike on the rear stand you use the go-kart wheel powered by the scooter engine to bump-start the rear tyre of the bike.

Looks cool, fits in the pits and doesn't require a car handy. But you've got to make it.
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MC28 SE -sold-
MC21 with RS250 engine -for sale-
MC21 race bike -soon for sale-