ok bro remember to keep ur itr rods n crankshaft n dun let the foreman
trade in ur stuff change to crv stuff ok those r bullshit. U can oversize to 81.25mm
or 81.5mm or opt for more power go for 83mm ford piston or je 84mm pistons.
but u need to do alot like valve to piston clearance(means u need to cnc or potong the
pistons for the valve angle to combust. then u need to press the pistons to ur type r con
rods but after doing it ur rods no longer can fit back the oem pistons than u must do up ur head oversize its combustion chamber to the piston size u choose n also the gasket coz they dun sell 81.25 or 81.5 gasket.Remember to check ur rod n crank bearings n remember replace them back to ori type r bearings that follow each colour that u took out from which rod n crank n since u have taken ur engine pls check the oil pump inner ring see it rotates smoothly not bit jam here jam there n also ur oil injector on ur lower block.
That could be that problem piston kong n ZTH members should keep note that oil pump is the heart of the vtec engine n be advise for most b-series bro check ur oil pump or upgrade to to oil pump.Ford piston 83mm or 84mm RM750,Piston job will cost u around RM 400,head oversize n block RM400 if cnc RM800,oil pump new RM480,rod bearing RM45 x 8,crank bearings RM55 X 10,
Alvin these r the few things i can help u list out n will slightly diff than the mechanic that will quote u either cheaper or more.
Remeber use back type r japan bearings not taiwan