Velocette Generator Speed Up

Machining At Sheddington

The generator (dynamo) on the Velocette was reconfigured to 12V before I bought it.

When I last rode the bike I noticed that it did not charge well at low RPM.

A bit of research at the University of Google suggested that the 12V generator needed high RPM before it would charge correctly.

The sheaves (pulleys) were measured and the following ratio was found.

Driver 3.125 Driven 3.000

Giving a step up ratio of 1.13:1.

I decided to aim for a step up ratio of 1.25:1

So the following sheaves were required.

Driver 3.125 Driven 2.500.

The tough part seemed to be finding a drive belt that would accommodate the difference in diameters.

A search of the usual places, Amazon, McMaster Carr etc, did no turn up any suitable candidates.

By chance, I was in the ACE hardware store nearby (Madam does not think that it was chance, as I go there every day)

They had drive belts of the correct cross section and suitable length. I bought the one that seemed to fit the dimensions calculated.

The next step was to make a new driven sheave.

However after some careful calculations, I thought that I could make the new sheave out of the old sheave.

This is what was determined to be the best option to reuse the existing sheave.

A mandrel was made out of a bolt to mount the workpiece and set it up in the lathe chuck.

It is shown here set up in the lathe with the outside diameter already machined to size.
Check the link below.

Machining The Sheave

Here you can see the finished article.

Do you think that Velocette used Mitsuboshi belts?


The installation of the new belt and modified sheave was completed and the results are to be found using the link below.

Up and running.

In this video, the speeds are a bit of a problem due to the reflectivity of the driven sheave.
It throws the measuring device out of whack.
I'll try that again after dulling the surface somehow.
Overall the goal has been accomplished.
More soon an an exciting (well not really) new development in the world of bikes and travel blogs.
As I told a finance guy that I know when he was expounding the excitement factor of tax protocols,
"Pretty girls and fast motorcycles are exciting, tax is just BLAH"

Ciao Bella
Norm