Single Cylinder Dragbikes

WHY would anyone build a dragbike powered by a single cylinder engine you may ask? Well quite a few people have over the years, and what is more been very successful. Aside from the virtue of light weight and low frontal area, if the cylinder is horizontal, I suspect that the huge gap of 720° of crank rotation between power impulses may improve traction.

THIS also can cause problems when a supercharger is used. Quite frequently builders have used very long induction pipes or plenum chambers after the blower in order to build up a sufficient charge to fill the cylinder. I have seen one set up where a second throttle plate was used near the engine to avoid throttle lag when changing gear.

SURELY one of the most successful single cylinder drag bikes ever built; 'Mighty Mouse' by Brian Chapman. The worlds first 8 second 500 (8.96 Santa Pod 1977).

Using a Vincent Comet engine with the cylinder almost horizontal, this bike exploited light weight and low frontal area to the extreme, and with fantastic results. Reliability and consistent runs in the high 8's gave Brian a number of British Championships as I recall.

Unfortunately the head and barrel have been removed in the top photo. Note the er... uncomfortable position of the inlet manifold with blow off valve facing to the right side of the bike. The tiny physical dimensions of this bike have to be seen to be believed. Note that the top of the 18" slick in the lower picture is higher than the fork top yoke! Note also long inlet manifold and long suffering Norton gearbox.

Photo courtesy Jon Spoard

Photo courtesy Bill Dossett

FROM the Netherlands, Jan Honee. He designed and built the engine in this amazing 500cc bike which ran an 8.13 at 160mph plus!

The fabulous engine has a four valve head with the valves arranged diagonally. Exhausts exit the head front and rear, whilst inlets enter from above the head. Final drive is on the right, note the size of the rear wheel sprocket! Latest news is that Jan is building a 2000cc 140mm bore single, I can't wait to hear that running - how many times will it fire over the 1/4 mile?

These photos were taken in 1993 at Avon Park.

Back in the UK and up to date, we have Peter Le Gros who based his machine on a 500cc Jawa speedway engine. Peter has provided some interesting information regarding his bike, and his plans for the future. Click here to find out more.