Tappet cap replacement

I now have found the actual fault with my Charging Set Lightweight 80W.
The little cap that fits over the tappet and presumably contains the shims to adjust the clearance, has broken.
It may have been a side effect of the exhaust valve sticking (it was somewhat stuck), causing the cap to dislodge and turn sideways, only to be smashed on the next cycle. The cap has broken in a brittle manner, a chunk of its side having broken away and yet to be found, showing a crystaline-looking fracture surface.

So what do I do about this?

a) Is this a generic kind of thing that one can just buy, along with a set of shims?
b) I could make a new one, but would mild steel be good enough? (It looks like steel). It must take a hammering (literally).

The shims are documented as being 7/32" diameter and .002" thick.

Why do you think there are shims, buy some silver steel and manufacture a cup then heat treat it but read up on it as you will have to temper it back because if you dont it will also shatter.

Martin P

Why do you think there are shims

Because they are listed in the parts list that someone sent me, including their dimensions - which makes them sized to fit inside the cup. And I do not see any other way to adjust the tappet clearance.

Fairy Nuff

Remind me what engine we are talking about please.

Charging Set Lightweight 80W c1945.
It was a purpose built thing so the engine isn't found for other purposes I think. Designed by Stuart Turner and built by everyone and their dog.

M0GXB wrote:
The shims are documented as being 7/32" diameter and .002" thick.

Whoa, they are tiny little things - from memory kitchen foil is about .001"
Villiers shims are about 7/16" diameter and 0.006" thick which I can cut with a pair of kitchen scissors.

In many ways it is a tiny little engine. The clue is in the name: "Lightweight"

(Which is why we love it)

M0GXB wrote:Charging Set Lightweight 80W c1945.
It was a purpose built thing so the engine isn't found  for other purposes I think. Designed by Stuart Turner and built by everyone and their dog.

Designed by Edgar Westbury and bulit by everybody (including Stuart Turner, Douglas, and E.Pass) and their dog. Westbury is renowned for his small engine designs, especially in model engineering circles.

As a youngster I was introduced to said Gentleman by my Grandfather at a Model Engineering event, dont remember much about the man except my Grandadfather thought he was God.

Maryalice