Morph wrote:Perhaps I am being dumb here

but doesn't the older Jabiru 2200 only run on AVGAS?
Hi Morph,
This is the later spec 2200, rated to run on Avgas or Mogas, 90 octane or above according to the manual. I am not sure but earlier models might have been different, I also think in certified aircraft you are only supposed to use Avgas, even if the engine is happy with mogas ! I know at some point a few changes were made, including the compression ratio, that could have an affect on the min octane rating of the fuel that could be used.
Here is an extract from the manual:
Engine Specification:
* Displacement........................2200cc
* Bore.....................................97.5mm
* Stroke..................................74mm
* Compression ratio..................8.0:1
* Rotation of Prop Shaft...........clockwise - pilot's view - tractor
* Ramp weight........................60kg (132lb) inc. Exhaust, Carburettor,
Starter Motor, Alternator & ignition systems.
* Ignition timing......................25° BTDC
* Firing order..........................1-3-2-4
* DC output............................10amps
* Power rating........................63kw (85hp) @ 3300rpm
* Fuel consumption.................13-14 l/hr (3 imp gph) @ 75% power
* Fuel....................................AVGAS 100LL / Mogas 90 RON
* Oil......................................Aeroshell W100 or 15W50 multigrade
aviation oil.
* Oil capacity..........................2.3l with oil cooler(2.2 Quarts)
* Spark Plugs..........................NGK D9EA - Automotive
Here is the "baby" to be delivered !
Happy flying,
Rudi