Hans Muller's WDM20

"Me and My Bike"
An introduction to Hans Muller and the story of the acquisition and restoration of his 1942 BSA WDM20.

Canvas Grips
Original replacement canvas grips for your WDM20 are no longer off-the-shelf items, so if yours are worn, or even missing, you will have to make them yourself. Hans shows you how here.

Leakdown Tester
This simple tool tests how much air leaks along the cylinder and valves of your WDM 20 (or any other classic or modern bike). Unlike a compression tester, this tool will not only show how high compression is, but also if it is low, why!

Ignition Timing
Hans runs down all the tools and techniques you need to set up ignition timing on the WDM 20 Magdyno.

Forgot the magdyno strap?
HORRORS! You've assembled the crankcase and you forgot to put in the straps that hold the magdyno in place. Fear not! Hans has a solution to save the day.

Gearbox Work
As well as complete instructions for dismantling and adjusting the WDM 20 gearbox, Hans describes a modification to simplify removal of the gearbox cover.

Cutting Leather Corners
Hans shows how to cut corners. Leather corners, that is, for the rejuvenation of your WDM 20 panniers. Includes a template for the corners.

Spring Puller Tool
Ever tried to install the original rear stand spring of a WDM20? Not an easy job, to say the least. To apply brute force to stretch the spring is impossible, there is simply no way to grab the spring and pull it. Hans to the rescue with instructions how to make this nifty spring expander.

Shortening the Rear Stand
Getting the WDM 20 on the rear stand is a challenge when one is past a certain age. After a few tries Hans came up with a solution: shorten the rear stand. Hans shows us how he did it.

Clutch Tool
The one-spring BSA WDM 20 clutch is a PITA to dismantle - if you are not VERY careful, the notched nut and spring will say DOIIING..!! and get into orbit in your garage. Hans' modification makes to the special tool more effective.

Replacing Oil Pump
The Army Manual states that "On no account remove the oil pump unless it is absolutely necessary". Removing it is no big deal, but getting the thing back in place is another matter, especially with engine in frame. Ingenuity to the rescue!

Rear Brake Switch
Unless you live on an island without other motorized vehicles, you will NEED a rear brake light; if not for legal reasons, it might just keep you alive. Hans shows how to add a brake light switch.

Technical Documents
Tech docs for the BSA WDM20: servicing notes, parts list, and wiring diagrams with wiring tips, PLUS a reprint of John Gleed's "Rebuilding the Pre-Monobloc Amal carburettor".