| 748 SP has steel rods but the race type (basically lots stronger than standard and about the same weight)
748SPS has Ti rods but not the race style, so lighter than standard and a little stronger (tho not as tough as the SP ones) a homologation thing really.
Corse rods are lighter and stronger than both but are outrageously expensive!
So, if your replacing rods with used ones i prefer the SP steel ones as they are bulletproof. also, the ti bolts on the ti rods can only be tightened 3 times and should be checked for stretch. (they are about £100 each! Ouch)
On the 748 the valves are the same size from BP to SP to SPS as are the heads (apart from cam profiles) But the pistons are high compression on the sp/sps not bp which is what makes them feel sharper than bp's. so if you're buying second had pistons be carefull you dont put the flat top BP ones in there or you'll have a low compression motor with SP cams and it wont be very happy.
if its apart, and you are buying pistons and barrels, get the 853 cc kit. its mega! but thats a different story!
when you have your pistons, rings, rods and crank on the bench, send them off to be balanced. daft not too when its apart, should cost about £100 all in and will make a big difference.
Good luck.  | 
wilf
Threaded Mode