The clutch is a dry clutch on the left hand side of the bike. It has a chain running from the engine to the clutch and behind the clutch a sprocket goes to the back wheel.
If you notice, speedway riders lay their bikes on to the left hand foot rest before the start of a race and let the wheel spin.
This is to keep the clutch cool.
This is because the dry clutch means it does not run in oil as most motorcyles and cars do to keep the clutch cool.
After a race the clutch is so hot that coolers have to be applied.