⭕ 1957 bsa gold star 500, engine number is DBD34GS21xx.

this engine was mounted on a BSA Goldstar bought last year.

With some difficulty to start (high compression) and very sporty dynamics (highly RPM), I quickly realized that this engine was highly tuned and that using it in the city would would be difficult. Thats the reason why I want to sell it.

After removing some parts of the engine, I have identified some changes to improve the performance:

- High compression piston (85.7 mm = bored +0.20),

- Valve spring retainer assembly (rotocap),

- inlet port extend,

- Dual spark hole (1 little (cold spark plug) and 1 normal (hot spark plug for start),

- roller lifter conversion,

- Cams with specifical radius for roller lifter conversion,

- Timing gear plate and cams with torrington bearings.

I dont have the history of this engine but I think it was modified since shortly because all the parts are in a very good condition.