 Oil was pumped to the top of the sloper engine but return was erratic and oil consumption very heavy.The main shaft was redesigned with larger ball journal main bearings, A smaller exhaust valve combined with a larger Amal monobloc carburettor gave the Model 120 28 bhp at 4500 rpm, an increase of 4 bhp over the Model 100.Motorcycle sidecars were popular at the end of the 1950s, so the Model 120 was provided with a purpose built sidecar chassis, connected by a three point mounting which provided minimal alignment problems.