Ariel Huntmaster vs. BSA A10

The purpose of this post is to look at the engine specifications, or the state of tune, for the various Huntmaster models and see how they compare with the closest BSA A10 models. We'll figure out which A10 is equivalent to the Huntmaster.

Here are the areas under consideration and the data I've found from reviewing the books:

Compression

• 6.5:1 Golden Flash & Huntmasters 1954-1959 
• 7.25:1 Optional for Huntmasters 1954-1959, standard for Cyclones
• 8:1 Road Rocket, Optional for Cyclones
• 8.3:1 Super Rocket
• 9:1 Rocket Gold Star

Camshaft

• 334 "standard" - fitted to the Golden Flash from 1950 - 1959 & Huntmasters 1954-1959 
• 356 "sports" - Road Rocket, Super Rocket until 1959, Golden Flash from 1960 & Cyclone
• 357 "race" - Super Flash, Spitfire Scrambler and Rocket Gold Star. Also fitted to the Super Rocket from 1960.
• 358 "acceleration".

Valves

• Inlet 1.406 Huntmaster 1954 -1959, Golden Flash 1950-1957, Super Flash / Rocket 1953-1960
• Exhaust 1.375 Huntmaster 1954 -1959 Golden Flash 1950-1957
• Exhaust 1.381 Super Flash / Rocket 1953-1960

No head changes for Cyclone

Carburettors

• 76/276 (1 1/16" bore) - Rigid and plunger framed Golden Flash, also swinging arm Golden Flash & Huntmasters in 1954.
• 10TT9 (1 1/16" bore) - Super Flash and Road Rocket, also Super Rocket until 1961.
• 376 Monobloc (1 1/16" bore) - Golden Flash swinging arm frame, Huntmasters 1955 to 1959 and Spitfire Scrambler (1956 - 1959).
• 389 Monobloc (1 1/8" bore) - Golden Flash 1960 on.
• 389 Monobloc (1 5/32" bore) - Spitfire Scrambler (1960 on), Super Rocket (1962 on) and Rocket Gold Star.

No carburetter changes for Cyclone

Conclusion

So there you have it:

• A standard Huntmaster is equivalent to a BSA Golden Flash, the most basic A10
• A Cyclone is close to a BSA Road Rocket, though with a slightly lower compression ration unless it is fitted with the optional 8:1 pistons
• My bike will be equivalent to a standard specification Ariel Cyclone.