Ariel 1955ca KH 499cc 2 cyl OHV 3407

Ariel 1955ca KH 499 cc OHV twin frame # CAPR 13268 engine # LE 787
Triumph starts a parallel twin vogue in 1937 and the other British manufacturers have to follow suit to stay competitive; BSA designs the A7 and in late 1947 Ariel comes up with the KH 500 cc twin. It’s designed by Val Page and well-received by the motorcycle press, who praise the pleasant and easy-going nature of the engine. Most of the design pretty much follows contemporary best practice, with a one-piece crankshaft carrying a central flywheel ring, and valve gear operated by two cams with widely spaced lobes. This put the cams’ stress points close to the end-bearings, which reduces any tendency to flex, and also means that that the tappets and push rods are well-enough separated not to interfere with cylinder block cooling.
The engine has 63 x 80 mm bore x stroke and a compression ratio of 6.8:1. This is good for 24 hp @ 6,000 rpm and a top speed of about 125 km/h. The 4- speed gearbox is a Burman product. Modifications for 1952 include a new flywheel assembly with a weight increase of about 20 % in order to provide a smoother engine and transmission. For 1954 a new swinging-arm frame is introduced.

The KH we present is a goodlooking older restoration. The frame number suggests it was once fitted to a 1958 model and the current registration mentions 1958 as year of manufacture but the general specifications of the machine and the engine number point to 1955. This KH comes with electronic ignition, Amal concentric carb and luggage rack.