Posted on the site http://www.thefang.co.uk/parallel.htm

“Mick Hand's 'Little David'. Based on the 1960's Honda CB72 and 20 years in development, this bike still holds the 250cc world record at 9.8secs! Crankshaft was modified to 360° configuration and primary drive converted to gear rather than chain...Compression ratio was 6.5:1 and boost from the Marshal cabin blower over 30 p.s.i...”

Any Honda twin I have ever seen had a 180° configuration. What advantage would there be to changing it to 360° like a British twin?

The domestic versions of the Hawk and Scrambler, sold in japan, could be had with 360° cranks just like the single carb Dream series. They used a single of points and a double-ended coil along with the 360° crank but were otherwise quite similar to the ones sold in the US. The smaller Hondas (CA 92/95, CB/CL 160, CB/CL 175) all had 360³ cranks.

mikeinidaho wrote:The domestic versions of the Hawk and Scrambler, sold in japan, could be had with 360° cranks just like the single carb Dream series. They used a single of points and a double-ended coil along with the 360° crank but were otherwise quite similar to the ones sold in the US. The smaller Hondas (CA 92/95, CB/CL 160, CB/CL 175) all had 360³ cranks.

Thanks for the information, mikeinidaho, but I was interested in why Mick Hand chose to modify the crank to 360°. It is clear that the fellow is some kind of mechanical genius and it would be great to know what advantages the modification gave.

Most of the export bikes were 180°, the CB77, 125s, 175s 250s and 450 included - you can pick it in the offbeat exhaust note. Its in the spec sheets for them too, google. With the head off, one piston is down a hole....

Supercharging a 180 twin is notoriously difficult, the longer dwell on one cylinder plays havoc with the mixture strength, so its very likely to be so it evenly feeds both cylinders.
Must be making serious horsepower with those times and that boost....

Asked on mc-engine list to be told as Rohan says = equal time of blower feed to each jug, other wise takes a huge air plenum not to starve some jugs or over feed others.

Thanks for the information guys but he could have used two smaller superchargers or one with a split chamber rather than making his own crankshaft. Building parts like that from scratch can't be easy.

What I am wondering is if the sideways vibration from the rocking moment of a 180° crankshaft would make the vehicle unstable at high speeds? My uncle had a Honda 450 Hellcat that went like a bat but wiggled like a fish at high speed. That sort of wobble is the last thing the rider would need on a drag bike going around 100 mph.

Anyway, the answer is probably not obvious so I will try to contact Mike Hand and ask him.

Supercharging a single is reportedly even more difficult than a twin, of any variety, so twin superchargers is not the way to go. The plenum has to be HUGE, and a backfire is not good....

Article on race CB450 Honda - they can be made to go.
Engine design has nothing much to do with handling, it seems, nothing a new frame won't cure....

http://www.motorsportretro.com/2011/11/drixton-honda/