When we featured the 1925 Grindlay-Peerless ST1 back in 2024, we looked at one of the most technically fascinating motorcycles of the 1920s – powered by the unusual 998cc sleeve-valve V-twin engine produced by Barr & Stroud of Glasgow. This article takes a look at some technical drawings that have recently surfaced, from under a bed.
Words: Rich Orriss
Drawings: Ian Simpson
The sleeve-valve engine was an ambitious piece of engineering. Rather than using conventional poppet valves, pushrods and rocker gear, the Barr & Stroud design used a moving sleeve inside each cylinder to control the inlet and exhaust ports. It was sophisticated, smooth and remarkably advanced for its time, although expensive to manufacture and ultimately destined to disappear as motorcycle engine design moved on.
Now, we can take a closer look at the engineering behind the engine itself, thanks to Ian Simpson.
Ian worked for Barr & Stroud on Caxton Street, Anniesland, Glasgow, many years after these engines were produced. He explains that, at the time, the company’s original engineering drawings from the 1920s were still held in the print room.
“40 years ago I worked for Barr & Stroud, Caxton st, Anniesland, Glasgow who made sleeve valve motorcycle engines in the 1920’s. At that time if you went to the print room armed with a drawing number they would print you out a copy direct off the original 1920’s linen drawings so I had 5 original prints from the sleeve valve drawings.“
“For 40 years these drawings have sat in a plastic bag under my bed,” Ian explains. “But these are of historical importance so I’ve just paid to have them professionally scanned.”
And that is what makes the drawings particularly special. They aren’t modern recreations or drawings produced from surviving motorcycles. They are copies made directly from the original 1920s engineering drawings produced for the Barr & Stroud sleeve-valve engine.
Today, the surviving motorcycles give us an opportunity to see the finished product… however these drawings give us something rather different – a glimpse into the engineering process behind it.
Thanks to Ian for preserving these drawings for so many years and, importantly, for recognising their historical value and having them professionally scanned. We are very pleased to be able to share them with Girder Club readers.
If you would like an original copy, please get in touch and we would be happy to share them – all thanks to Ian.
an article by The Girder Club
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