The older RR ones are not the best engine around . Yes , the sprag clutch is a pain in the arse but I think there may be an option to change to a new lightweight pre-engaged type starter which I believe also fits the O-200 too . The cylinders have been known to crack ( and even come off ) around the cylinder head/barrel join !! The thing is the poor things get a hard life usually as they are normally fitted to FRA150 aerobats !
VK