Not the best of Chrimbo suprises.

Is that the result of a broken ring
I still need to sort the barrels out on my Uni-Trak (Snotter). Genuine oversize pistons seem unavailable. Most cost effective upgrade is an 1170cc Wiseco kit (Jeff at Z1enterprises would be a good place to start).
I have considered another couple of options, but not explored them properly;
1. Rebore a set of Z1000J (998cc) barels to fit your existing pistons & fit new rings (Thats if there is enough meat on the 998 liners).
2. Have new sleeves fitted by the like's of SEP & bore to suit existing pistons with new rings.
I'd be interested to hear if either option is viable. I may be able to help with pistons if yours are F.U.B.A.R.D.