Questions? Looking for parts? Parts for sale? or just for a chat,

The WD Motorcycle forum

WD Motorcycle forum
Start a New Topic 
Recent owner with a few Q!

Hi all.
I'm new to the classic bike scene and decided to buy a BSA WM20 as my grandfather rode one in 1944/45 whilst he was in the MP.
Now I'm the proud owner of a 1945 WM20 fitted with a 1939 engine. It has a black out light, panniers, a field stand, brass levers, chain guard top and bottom, brass plate on back giving military reg, rebuild date plate on side valve plate, convoy rear light etc. Ive used it for a few runs out and its ridable (I put an MOT on it to be sure) but now it needs some jobs doing so I can enjoy the rides more often!

Now for a few questions!

1. I need a new front tyre as there is some cracking and it keeps going flat. I was going to buy an Avon Speedmaster 3.25 / 19 as it has an Avon on the back and the front is a 3.25. looked through the forum and as with all forums there is mixed advice re the 3.25 vs the 3.5. Does it matter which I go for?

2. The front steering damper has snapped at the bottom. I can remover the long steel bar with the Bakelite knob at the top but there is noting else attached or present top or bottom. The bottom has about 5 thread on it but most are rounded off and its pretty much smooth. The forks have some slight movement (less than 1 mm forward and back) and so does this mean I just need to replace the steering damper or does it mean that I have to strip and rebuild further. Ideally I want to keep the bike as original as poss and do not want to build a shiny 'better than new' bike so I only want to replace what I need to be able to use it (It did pass an MOT last year with an experienced classic bike owner / tester so the movement isn't huge).

3. Finally, I need to replace both fuel taps. One is completely seized. The other leaks. What type of fuel taps would be sensible to fit.....the ones on it at the moment look like brass. Ive looked on line and the replacement ones on offer don't look like mine.

I'm know ill have plenty more Q coming up but I didn't want to put too many in this thread!

Here's hoping for experienced help and advice!



email (option):

Re: Recent owner with a few Q!

Hello Simon,

Congratulations on your bike! It sounds as if it's in excellent rideable condition.

The first thing to do is choose your preferred tyres. Don't wait for punctures or worse. Your choice will depend upon the price of replacements and tread pattern you like. I put 3.25s on my bike because they are readily available and cheap. You may feel differently about what you want.

The steering damper is not a huge problem, I think, on modern roads at reasonable speeds. Many of our wm20s don't have one at all.

As for the fore and aft play on the steering head, try to find out if it comes from the steering head bearings or from play in the fork side plates, or both. I'd say that 1mm is really not at all bad! Not all bikes from this era had absolutely tight steering heads. Unless it bothers you, don't worry yet. The steering head bearings are a bit of a pain to get at and replace, but it's not complicated. New bearings shells are available.

I hope this helps. There are many people far more expert in maintenance matters than I am, so perhaps you'll get some other advice that I'm giving you here. I can only say what my take is.

Best wishes, Allan

email (option):

Re: Recent owner with a few Q!

About the taps,I found it hard to get my original taps not leaking. They were always dripping and there was a strong smell in the barn.
So I bought replicas that where even more impossible to get dry !
But now there are again new made taps that really work well. But they are chromed. If you want them you have to check carefully where you buy.

Re: Recent owner with a few Q!

Thanks for the advice.
Going to go for the Avon speedmaster 3.25. It will match the rear and I don't want to rely on the old cracked tyre on it now

The movement in the forks is coming from the headstock area. I'm assuming a worn bearing. It's about 1mm movement so I'm still not sure if it's worth chNging or not. The steering damper might not do too much but I have decided to replace it anyway so it looks stock. Still deciding whether to strip the girder forks any further though....the side friction discs look work out and very old. Is it worth replacing or will I be wasting my time.

As for the taps, I've seen some at dragonfly spares, but they are nickel plated. I was hoping for brass finish. Does anyone know where I can get some (hopefully ones that don't leak :-))

Once if sorted these problems I'll be turning to the carb, oil leaks and clutch adjustment. I'll post on these at a later date if I can't sort the issues :-).



Re: Recent owner with a few Q!

The 'Speedmaster' is a ribbed tyre, and not of a sort that would have been fitted to a machine with off-road pretensions. Is your bike in WD trim ? A block tread such as the K70 or an Ensign would look more the part. I don't think that you'll have tyre compatibility problems within 'our' performance envelope, any more than you'd need to balance the wheels.

If the head bearings are not indented or 'notched' then it should be possible to adjust out any play. If the play is in the spindles then it needs sorting. There is a world of difference in riding a girder-forked bike between one with shagged forks and one that is as the maker intended. Fork friction discs are worth doing. You'll normally be riding with a fraction of friction on and if they are shiny and grease impregnated then they won't be fully functional. There is an eBay seller who lists replacements.

The Enots taps don't seem to have been made in plain brass and were always plated. The best working replicas are those made in the Czech Republic by Jiri Horice (Vintage Replica). They are properly made as per original - and the originals don't leak unless they're completely worn or dried out.

Re: Recent owner with a few Q!

Just a word about an aftermarket steering damper assembly I bought off eBay recently. The thread at the bottom of the rod was too small and jumped when tightened (sidecar setup) and the thread at the top into the knob was a LH thread which I just couldn't understand.


email (option):

Re: Recent owner with a few Q!

A lot of rubbish is made these days.
Like the taps.

Re: Recent owner with a few Q!

FWIW I ran ribbed fronts on my M20 since 1991 and by prefference would not run anything else.
I found the handeling with the ribbed tyres to be so much better it was not funny.
The only reason I have changed to a Metzler is I can no longer get any ribbed tyre down here other than Avon speedmasters that are V rated and priced over $ 200 ( Aus ).
While my bike is a bit fast, never going to challenge a 100mph tyre.

As for steering , place your finger over the joint between the lower steering bearing and the bottom yoke.
There should be NO, ZERO, Nill , Nada play if there is the bearings need attention, new balls are cheap.
Because of the way girder forks extend it is hard to distinguish between steering bearing play and side plate play.

You can use the same method with the side plates, place your finger over the joint and push down on the front end with the brake applied hard.
I pull the brake on then slip a nut between the lever and base , ground to a V shape so both hands are free to do the testing with.

On any newly acquired girder forked bike it is essential to remove the side plates and check for both wear AND CRACKS.
Never found one that did not need new bushes and came across a few that had cracks which is not funny should it fracture through while breaking heavily.
Similarly the legs themselves should be very carefully checks for cracks, particularly at the brazes which is a stress concentrating point.
Seen a lot that have broken clean through while the rider was on board, again not a pretty sight.

When you have been riding for a few years and are used to the feel of the forks, you will be able to feel that something is wrong but right now you are a novice.

Unlike a teleforked bike, girders steer strait and remain strait under breaking so my steering damper is something that is not used a lot, but the fork dampers have been replaced at least 3 times if not more .

Girder forked bikes are very sensitive to tyre pressures and I have to run at least 24 in the front or the bike tank slaps at the slightest provication.
Tyre pressures in the book is for 1940's tyres which have not been made for 70 years and modern tyres have a lot softer sidewalls thus need more air.

Fuel taps.
Soak them in warm penetrating fluid then pull them apart
You can still buy NOS corks for the taps or enjoy a nice bottle of white with a solid cork.
Turn it down to size on lathe, in a drill or in my case with a cork bore ( lab equipment still readily available & very handy )
Clean the parts up with a soft brass brush then soak the cork overnight in warm water.
Assemble using some BLUE locktite till the slide is just locked up.
leave it overnight and then the slide should be stiff to move & you can install them into your tank

email (option):

Re: Recent owner with a few Q!

For fuel tap corks, I use synthetic wine corks which need no conditioning. Just cut to size and use a hot needle to make the hole in the middle. I have had mine working fine for 10 years; they dont dry out.

Nieuwe pagina 1