Saturday, June 3, 2017

Yamsel V4 500

This very special bike was built in 1974/75 by Geoff Sherwill and Lyell Williamson. Using 2 Yamaha TZ250 engines welded together and fitted into a 1971 Seeley frame. The original idea was conceived by Brian Thompson to create a wide angle V4, by using 2 Yamaha TR2 350 engines with carbs facing forward in the V. With limited budget and plenty ideas, Geoff and Lyell decided to build a R&D bike. Geoff undertook all the machine work and creating a jig/plate assembly, the case was welded together with both crank pinions driving direct to the clutch hub primary gear. This set up created extra long and angled inlet manifold tracts which wasn't ideal. To solve this problem Geoff was planning the inclusion of custom cast wide angle crankcases for the final engine. The first outings showed the engine to be reliable and only minor issues with cooling and ignition were evident. With Lyell riding the bike for 3 years and with ongoing modifications race results were several placings together with some top ten finishes. It was last raced in 1979.

Chassis: 1971 Seeley
Forks: Yamaha RD350
Yokes: By Geoff
Swing Arm: By Geoff, using yacht mast, no square or rectangle extrusion available back then
Wheels: By Peter Allen & Jack McDonald, cast at Commonwealth Aircraft Corporation
Tank: By a friend of Bill Horsman
Exhausts: By Lyell
Paint: By Border Signs 
For more pics see
Yamsel V4 500