Terry,just spend a bit extra and fit a Rotax engine.If you go for a cheap alternative you may well end up with "a lightwing with no engine" at 100' agl after takeoff.
The only problem I've personally had was the flywheel bolts shearing on startup (I was lucky,one bloke I know had it happen at altitude).It was a saw blade spinning at 2800rpm and made a mess.There have been other problems with our 2 club Jabirus including cylinder through bolt failure,dropped valve,broken conrod,excessive oil use caused by overheating/excessive wear from factory economy kit.Our club sold its last Jab just over 2 years ago and bought a Foxbat.The Foxbat has done over 700 hours in our ownership with a 100hp Rotax 912S and has never had a spanner on it apart from scheduled maintenance.The actual time on the engine is 1080 hours and it runs like new.TBO of 1500 hours looks very acheivable.I have NOT seen a Jabiru engine reach TBO without major maintenance.