Hey, KHB makes some piston/liners for the O.S. .12 CV-R and .15 CV-R. Either graphite or copper piston and silver sleeve, no idea what difference the graphite will make...Probably cause bad balance.
Take a look:
http://www2.towerhobbies.com/cgi-bin...?&I=LXGRN4&P=7
http://www2.towerhobbies.com/cgi-bin/wti0001p?&I=LXGRN7
Lucky me, duratrax make a true ABC sleeve/piston kit for my .12 CV for just $19.99, the bearing replacements are also 1/4 the cost