Chain case Rubber Bung

Do you mean the rubber bung that is used to access the clutch pushrod adjuster? If you do, the reason it isn't in the parts book is that your age of bike shouldn't have one. Much later bikes did, so you'd need to look at parts list for one of those, like an Atlas maybe.

If you don't mean that, then a picture would help.

Ian

hello rubbers bungs are standardised  so go to your nears motor factor dealer and you buy one there normally they come in pares  so see Halfords or other motor factor outlets   yours anna j  

This very club has them. Look in NOC shop, under heavyweight twins.

Item number A2/488.

52p+p&p.

Never heard of 'Servis' tyres, but then I only ever use top brand rubber as I like to ride using the bikes performance and also don't mind the rain. Never understood why people put cheap tyres on a bike or car worth thousands. Each to their own though. 

It also sells part no 25341 in heavyweight twins at £1.50

Back in the day Firestones lasted for ever, but ran for cover when it rained.

Modern  equivalent sizes   often come up too wide  ,go carefully.

Don't go over the 3 inch front size or it will rub on the bridge. Probably.

Motorcycle press articles recommended adding the bung hole to earlier bikes. No doubt that's why you have it.