1957 bsa gold star 500, engine number is DBD34GS21xx.
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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. That's 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 don't have the history of this engine but I think it was modified since shortly because all the parts are in a very good condition.