Introduced around 1925 the Style 4 undertook several major changes. The previous two piece base casting was now formed as a one piece crankcase as illustrated. The governor was now housed internally on the left hand side of the engine, this feature was used to promote the engine since it would require less maintenance and would ensure even running. Again, the governor remained of a throttle design with the governer acting on a butterfly. This engine was offered in a range of sizes in both petrol and pariffin - 3.5, 5 & 7 HP on petrol and 4 & 6 HP running on paraffin. It is not known exactly when production ceased however it is thought to have been in the early 30's with the introduction of the Pre-WD type engines.