Franzis Revives Its 1:2 Scale BMW R90S Engine Kit With Working Internals

Model maker Franzis has brought back one of its most admired builds: a half-scale, fully working replica of the air-cooled flat-twin that powered the BMW R90S. The reissue lands in 2026, timed to mark fifty years since the R90S scored a pair of famous race victories in 1976.

The kit first appeared in 2019 and quickly found a following among vintage BMW enthusiasts. Roughly 200 transparent components press and screw together without a drop of glue, letting you watch the internals operate. A small electric motor drives the assembly, so the crankshaft, connecting rods, pistons and valves cycle together the way they would in a running engine. Two red LEDs inside the cylinder heads flash at the moment ignition would occur, and the five-speed gearbox clicks through the authentic 1-N-2-3-4-5 shift pattern.

BMW launched the R90S in 1973 as the flagship of its /6 line, with styling by Hans Muth, who would later pen the Suzuki Katana. Its 898cc boxer ran 38mm Dell’Orto carburetors, made 66 bhp and could touch 124 mph. In 1976 Steve McLaughlin won the first AMA Superbike race at Daytona aboard one, teammate Reg Pridmore took the inaugural championship, and Helmut Dähne and Hans-Otto Butenuth claimed the 1000cc class at the Isle of Man Production TT. Just under 17,500 were built before the R100S succeeded it.

The model stands about 10 inches tall and spans 13.4 inches across the cylinders, and Franzis estimates three to four hours of assembly. It rests on a display base holding three AA batteries plus a sound module that reproduces the original engine note, and it ships with a 120-page bilingual companion book on the boxer twin and the R90S. Designer John Anson, also behind Franzis’s 1:4 Porsche 911 flat-six kit, developed the model.