Hi ETOPS
Sensible question. The Schemmp-Hirth 'turbo' gliders (a bit misleading, they have normally aspirated 2 cylinder 2 stroke retractable engines) start by windmilling the engine. There is a decompressor which helps to get the prop spinning fast enough for the engine to start, and an electric fuel pump to get fuel flow started, no choke so the mixture is not made richer to cold start. The engine also has a cutout for overspeed.
Start procedure then:
Engine master on
Switch to extend engine
Fuel cock on
Fuel pump to on
Ignition on
When pylon fully up (green light on control unit )
Pull decompressor
Increase speed to manual recommended IAS (for my glider 68kts)
When engine is turning, release decompressor
Assuming engine fires on both cylinders, reduce speed to best climb (for my glider 55 kts) or overspeed will cause engine cut.
It may sound one-armed paperhanger, but with regular practice (one carries out a regular engine check) maximum height loss (decision to low point) can be as little as 300ft, but more usually 400 to 500. But if the engine doesn't start, it is in a higher drag configuration and 500 feet lower than before. I never had a non-start in 10 years of ownership, but I always decided to start the engine at no lower than 1,000ft, with an alternative plan available for a non-start.