after reborning, you should not rev it high or into high speed coz it's still new piston anyway, the resitance between the piston, piston ring n blok still not 'seragam', have to run it maybe 2-3 weeks.check with ur mechanic, ask him reborn with wat spec like for longer smooth or for racing or medium smooth or did ur mechanic changed ur oil or something like tht la
wat kind of engine oil did he used?
if u wan long lasting, better use those expensive lubricant around 200 lo coz new piston need good oil so the resistance could be minimize
but sometimes the timing belt adjusted wrongly also can lead to ur problem
just my 2cent opinion
sorry if i;m wrong