I made a rubber sleeve, copper pipe, clips, and at the lower end of the pipe a “P’-clip for the Oil tank vent. (under the oil tank) See picture. However there is not enough space between rear mudguard and gearbox. This means the Gearbox / Prim Chain adjustment cannot completely be done. Was my BSA WM20 1942 original fitted with these parts? What is the easiest way to make space?
Thanks in advance, Lammert de Vries

Lammert, I do not think the oil vent pipe has to be that long. Mine is only 10 cm.

John

email (option): john.kater@chello.nl

Lammert,

Pipe length of several original examples of 66-8330 Oil tank breather extension pipe = 8 inches (203mm)
If you wish, you can make longer and bend to direct any oil to rear chain.

Re gearbox adjuster clearance

1. Are your adjuster parts correct?
CAUTION! There are rear gearbox bolts with shoulders of various lengths, collars of various lengths and adjusting stops of various length, precise origins of all are unknown to me.
Some of the shorter parts are pre WW2
Over the years the parts were changed, but sometimes part numbers remained the same, very confusing 70 years later when building bikes from parts!
All parts must match or assembly problems may arise.

I do not have a 1942 parts book, but can tell you for most WM20:

a. The rear gearbox bolt should have an effective length under head (including shoulder)of approx 4.1" (104mm).
b. The collar/spacer for rear bolt should have an overall length of approx 7/8" (22mm).
c. The adjusting stop(yoke with stud)length of yoke to gearbox mounting plate is approx 1 1/4" (32mm)
With the above parts your adjuster nut should be well clear of mudguard.

email (option): n.gentner@bigpond.com

email (option): john.kater@chello.nl

John and Neale thanks for answering.

A shorter pipe will solve the problem. But is not what the BSA Engineer had in his mind when he developed part number 66-8330 with a length of 8 inches. My parts are in accordance with the dimensions given by Neale. My adjuster nut will well clear the mudguard, it is the pipe between Gearbox and Mudguard that sticks when I have to readjust the Prim Chain in the future.
Should I have to bend the top of pipe in the direction of the Prim Case? Then the pipe is clear of the Gearbox Inspection Cover. What about that?

Is the tube on the inside or outside of the gearbox plate and I have no problem there. Look at the photo, no rust at all

email (option): ahum@quicknet.nl

Henk, thank you.
This makes the difference. Somewhere I found a picture as my example. Pipe inside the Gearbox plate. Wrong example I guess now. My pipe goes to the road at backside of the Gearbox between Gearbox and Mudguard. I think your pipe goes along the Gearbox between left side of Gearbox and Prim Chain case. I feel, I, ask much, but I should like to have Picture of the top connection of this pipe to the Tank.
Thanks in advance, Lammert

Here a photo of an original new old stock pipe. The bend in the pipe is as it should be.

Henk

email (option): ahum@quicknet.nl

Henk,thank you for the Pictures.
Lammert