I remember the older Japanese were so bad on the HP claims we took to calling it Pony Power. One bike was claimed to be making almost 80 HP and a major mag ran in on the dyno and the best they could get was closer to 55.
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Almost (if not all) companies list the vehicles horsepower as that which the engine produces at the crankshaft.
All of the dyno's available to the average rider measures horsepower at the rear wheel.
There is always a significant loss of horsepower between the engine and the rear wheel due to a host of reasons from the obvious like chain friction to the more subtle like oil pumping and oil displacement between the gear teeth and between the rolling elements in the bearings with their outer/inner races. Add to this the sliding friction between the gear teeth and between any bushings and shafts.
IMO, Royal Enfield is doing quite good to only lose 7 horsepower (26%) between the engine and the rear wheel.