14 Page – PDF Download – Complete Series – BSA Gold Star CB500 Engine Stripdown
“Bringing a Goldie back to life
BSA Gold Star engine strip: part one
The 40-year-old 500cc engine had not run for at least 20 years. The buried treasure was taken to John Gleed for a complete overhaul. He began by stripping it down. This strip can be used for B31 and B33 engines.
One of the most famous British motorcycle engines, the Gold Star owes its heritage to the standard B31 and B33 engines. Much of the information contained in this article is applicable to those units too.
The subject of our strip and rebuild is a 1955 CB500. the machine had been stored for over 20 years before Eddie Marshall of Barnsley snapped it up and brought it to me for restoration.
- Externally, the engine looks in reasonable condition. No broken fins or other damage. The carburettor extension is not standard and the finned tappet cover is an Eddie Dow product. Any oil in the sump should be drained by removing the sum plug.
- Start by removing the timing cover. Note the timed breather driven by a peg on the magneto pinion, and the light spring that presses the sleeve against the cover.
- Next take off the tappet cover. It’s held by four screws.
- Unscrew the nut holding the magneto pinion which is removed using a special extractor.
- After removing the clamp bolt on the magneto securing straps the magneto can be lifted off. There may be shims underneath for correct meshing of the timing pinion.
- On this engine the mag strips are not correct. They are from a B31 and are narrower.
- Now rotate the engine until both valves are closed at top dead centre. A useful handle to turn the engine can be made from an old shock absorber sleeve…”
The full BSA Gold Star CB500 Engine Stripdown and Rebuild, with photographs of each stage, is covered in this article.