The 600cc engine has a 90mm bore x 92.5mm stroke. This is not merely an engine with a bigger bore barrel, it has a reinforced cylinder barrel made especially for this model, with a modern flat piston design, modern cylinder head layout, and this engine includes all the improvements on the standard engine. Max. rpm around 6700. Compression is 10:1, so this engine is not only very fast but also very reliable. Used mainly in moto-cross and for street bikes that want the extra speed of a 600cc engine, with the outward characteristics of the 500cc Gold Star. It is not suitable for 500cc Classics racing.
Standard Gold Star gets 600cc engine.
This lovely Gold Star still fitted in the photo with the 500cc standard ABSAF engine, came for an upgrade: 600cc engine with alternator crankshaft and primary chain case and ABSAF CDi magneto.
Standard Gold Star engine with alternator conversion
As you can see the cover is slightly larger than for an original Gold Star, but the result looks powerful.