Plug & Play 1070cc Displacement Big Bore Kit.
“Piston capacity can only be replaced by even more piston capacity” – this was the adopted motto during the Siebenrock's-internal development of the Big Bore Kit. The goal of this construction was to enhance the motor characteristics which were already outstanding thanks to the Power and Replacement Kits. They did it and the result for all BMW 1000 cc models from 1981 on-wards was the 1070 cc Big Bore Kit, which turned out to be the ultimate solution for sporty touring riders. After modification, an amazing 80 hp is available at an engine torque of 92Nm.
This performance boost was achieved using 151 millimeter long, high-stability connecting rods which, when weight-optimized and fitted with ARP screws, only put 450 grams on the scales. Quite apart from this, 98 millimeter, weight-optimized pistons are used which only weigh 428 grams including the rings, bolts and clips. Thanks to the well-designed piston form, it is not necessary to adapt the cylinder head to the big bore.
All of the parts required to mount the kit are included except the crankshaft bearings, see CSBearing460
if you need to replace them.