Vintage Thing No.62 - Buckingham 4 valve JAP 500

The Buckingham 4 valve JAP was built by Graham Buckingham, a technician at Coventry Polytechnic when I was a student there in the early eighties. I was making a mock up of motorcycle riding positions for a project and he took an interest in what I was doing and eventually let slip that he had designed and built a motorcycle. I was immediately fascinated and in response to my constant questions brought in what remained of it.

The curious influence of the moon and tides on the flotsam and jetsam of my photographic print collection brought these snaps of it to the surface the other day so I thought I would record what I could remember of it now before these snaps disappear again.

The engine was a four valve conversion of – no less – a speedway 490cc JAP engine. Graham said he had a mate who worked in the Jaguar drawing office and it was he who drew up the head. I think he said the valves were Jaguar parts. No Jaguar engine had four valves per cylinder until much later. The camshafts were driven by another advanced feature for the time - toothed belts running from the nose of the crankshaft.

There were roller cams to reduce internal friction - always a nice feature I think even if many engines manage quite happily without - and these operated the valves through forked rockers. The rockers pivoted on bearings with their own external oil feed.

The new head doesn't have much in the way of cooling fins but would have run on alcohol anyway. With dope's higher latent heat of vaporisation, this gives an internal cooling effect as well as allows the higher compression ratio that was meat and rink to the venerable speedway JAP 500 that ruled the roost for decades until Weslake and Godden 4 valve engines came along in seventies.

From an aesthetic point of view I reckon it has that wonderful one off, handmade, prototypical look that I so admire. There's something fine about beautifully cast aluminium - the Italians do this so well I feel - but this engine has a wonderful homely look about it. You almost feel in touch with the artisans who made it just by looking at it.

Graham also brought it in the wooden pattern for casting the new head and rocker box. This was made in the traditional way with wood but the green stuff is body filler, which is much easier to work. Having sculpted the desired shape, this was varnished and a casting made. I suppose getting an item cast in aluminium was no problem at all in the Coventry of the 1960s. Graham might even have done this in his own backyard foundry. Then there were all those little workshops across the city where any machining could be undertaken.

The chassis was just as interesting as the engine. It was a glass fibre monocoque. I can't recall what year all this radical stuff was going on but - didn't they do well? I think it must have been mid-sixties so monocoque motorbikes were very exotic. In speedway circles (ovals?) they must have been unheard of.

This is the pattern for the GRP moulding. I am not entirely clear about how the rear swingarm fitted and as the machine was designed to speedway or grass track use the steering angle was quite steep. But a subtle modification to the mould and I suppose an angle more suited for road or track use could be incorporated.

The depression in the top of the frame is for the fuel tank, which clipped in using rubber bungees. That's what the two depressions on either side are for. The seat attached in a similar way.

Graham reckon that the chassis was actually too stiff, which led to a good-natured argument with one of my friends, Geoff Bird, who later became famous for his human powered vehicles. As far as Geoff was concerned, no chassis could ever be too stiff and I would agree with him. In Graham’s defence, however, it could be that the suspension units of the day simply weren't up to the task.

That's about all I can remember about the Buckingham JAP 4 valve 500. I don't know when it was built and I can't remember ever discussing its competition history with Graham but I found it rather inspirational.

In the best traditions of the Internet, I am sure that somebody out there knows something and it will only be a matter of time before they get in touch.