The design is accurate and keeps an even width of gasket metal along all parts of the joint faces. It also fits the bolts and studs well. As supplied the gaskets are made from C106 copper sheet which is vacuum annealed after the laser cutting and so do not need to be annealed before fitting. Although C106 grade copper is the softest grade of copper sheet, as supplied it has an allowable Vickers hardness spanning the range 40 to 120. Our vacuum annealed gaskets are right at the soft end of this range (typical test value 42.5 Vickers HV1). These gaskets can be reused if undamaged but would need to be annealed again before reuse.
Oil leaks from the rocker box joint are a common and difficult to cure problem with these BSA twins. The tendency to leak is exacerbated because the cylinder head steady, which connects the frame and the rocker box, can put lateral forces into the rocker box that tend to make the rocker box move relative to the head, which is bad news for paper and composite gaskets. Copper gaskets partially harden as a result of the pulling down process. During tightening down the rocker box, the gasket fits to the rocker box and the head, so that tendencies to move sideways are appreciably lessened. If the joint faces have any scratches it is advisable to use a small amount of gasket sealant, which can be applied to each side of the gasket and allowed to go tacky before use. A note on fitting the gaskets is available here.
150914 © Ebor Bikes 2015