BSA A65 piston rings 650 Size .040 40 over Grant USA Made 75MM Ring set Lightning

You are bidding on a brand new size .040 Piston ring set for all BSA 650 unit twins Grant USA Made. Includes everything you see in the picture. These are brand new, never installed, and are quality parts that are proven.

Piston ring gap:

The new industry standard for British motorcycles is to gap the rings at .020 / New independent lab tests and studies (in the USA and England) show that any gap between .024 to .010 is efficient, and does not show more oil loss than normal gaping at .010 to .014 or does not show any less engine performance, or any extra loss of compression.

I understand that this information might be difficult to accept or understand because the way we have been doing things for the last 80 years but all the rings that are coming out of the USA (Hastings) are using this standard and the gap spec is .020 / JCC and Hepolite are also using this standard

If you are a purest or are racing the bike and want every mechanical advantage possible, we can have custom rings made with a gap of .010 and three piece oil rings, A piston sample is needed for this process.

In most maintenance manuals it says if the gap exceeds .014 then renewal is necessary.  This reason is more because if the gap has moved that much you know the knife edge of the rings is worn and or rounded, and at that point there will be so much corrosion from engine gases that the rings need to be renewed.