Hi guys, would like to add my two bobs worth to your discussion. I fly a club jab which started to use a lot of oil (140ml per hour). It caused a lot of tension in the club, trying to work out what the problem was, when a club member (engineer by trade) explained his idea on how to fix the problem. Once he got the go ahead from the club, he made up torque plates for the barrels and heads the barrels are then bolted to the torque plates to the right tension then honed so when you bolt the barrels back on the block to the right tension you you have round bores. The heads are bolted to the there torque plates valves reseated add KY valve guides.Now our club jab burns very little oil (with original pistons and rings) and runs sweet, and I mean sweet, no more typical jab clatter fixes alot of jab motor probs. Cheers Phil