After searching in the USA and getting a feel for prices, I just bought a second hand Sonex with a Jabiru 2200 which happened to come up on the local market. It had 110 hours on it. So far, so good, but there are a few minor changes needed. e.g. although it has dual controls, the throttle is on the left sidewall, so that's a bit inconvenient if I ever want to let a mate fly it from the left seat but still wish to have proper control from the right seat. Also the cable exits the throttle plunger tube and then, within 6 inches or so, takes a right angle bend across the cockpit, then another near right angle bend to go out through the firewall. This is a Very Bad Thing. I am thinking of ordering the factory Sonex lever-type throttle and mounting it in the centre.
Another thought is to replace the Bing with the Aerocarb - I would appreciate knowledgeable comment on this. The engine warranty has long since expired, so that is not an issue.
If you fit an Aerocarb I suggest that you encase the throttle cable in tubing as it feels soggy and the carb has a tendancy to jam at idle. If this happens you have two options; Stop the engine reposition the throttle and restart; use 2000rpm on approach with full flap if the throttle jams go back to T/O flap and you should make the touchdown point OK. Use lubriplate grease on he slide on your annuals; better still use the Sonex Lever Throttle that pulls rather than pushs to open! Don't even think of an Aerocarb without an EGT gauge.
Thanks for the advice. I have fixed the throttle cable problem. And decided to stay with the original Bing carby for now, just because it starts and runs smoothly. On the basis that if it ain't broke, ain't gonna fix it.
Am thinking for typical Australian operations the Sonex could do with bigger wheels than the little 5 inchers it comes with, but otherwise I am very happy with it.
I ditched the 5 inch wheels, gear fairings and wheel spats. Fitted 8 inch Azusa Tristar wheels. The old Azusa brake drums went straight on and the original axle spacer size is OK, but a couple of extra 3/4" washers were needed because the 8 inch hub is slightly narrower than the 5 inch. Same bearings.
Getting ribbed tyres in 6 ply for the 8 inch wheels seems impossible. All the local offerings were cheap and flimsy 4 ply junk. I have put 6 ply boat trailer tyres on... It doesn't look as crude as I thought it would.
Ground handling is much improved. Turning is easier and it accelerates quicker, presumably because the rolling resistance with the larger diameter is less. Braking may have been slightly compromised (to be expected with the original 4 inch drums) but the Sonex will stop in any strip it can take off from anyway without much braking. Nett weight change was almost zero because of the spats etc being removed.
I don't know what effect all this will have on cruise speed yet, but I'm guessing no more than 3 knots. Worth it for the peace of mind on rough or soft strips.