Ariel 1931 Model SF 499cc Sloper
The sloper engines were designed by Val Page in 1926 shortly after he left J.A.P. to join the Ariel concern. Two versions of the 499cc OHV engine were produced, the 4 valve SG and the 2 valve SF, both driving through a Burman 4-speed gearbox.
Courtesy New Zealand Classic Motorcycles