BSA GOLD STAR
My workshop recently played host to a reasonably rare visitor, a BSA CB32 Gold Star. Its build date of 1954/55 means it's an example from fairly near the end of the line for the smaller Goldie. I was told it had been running but it lacked compression and power. Also, the front end felt like it was going to fall off!
I decided to take a look at the engine first. Once the cylinder head was removed it quickly became evident that a badly fitted and blown head gasket was the main culprit. This was one of the laminated gaskets where layers of around 0.002” thickness can be peeled away to fine tune the compression and oil sealing. The latter also involves a proud spigot sticking up from the liner in the barrel, and a suitable recess for this in the cylinder head. A similar set-up is seen but rarely used to full advantage on the Royal Enfield Bullets, where an ordinary head gasket is usually expected to keep the compression and oil in all by itself.
Back to this BSA. The head gasket had been fitted in such a way that the barrel spigot and the recess in the head had bitten out a chunk of the gasket as they came together, so a proper compression seal could not be made. Even though there appeared to be no evidence of an external blow, there were several black tracks leading to a few of the stud holes and the pushrod tunnels.
On top of this, the exhaust valve – a very rare item, apparently – was very floppy in its bespoke-looking guide. I was reluctant to mess with this guide unless absolutely necessary, fearing opening a can of worms.
