Shed Zed packs a bigger head: Kawasaki Z1 Super Six from Allen Millyard

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Shed-based engineering hero, Allen Millyard is putting the finishing touches to his latest project, a pair of six-cylinder Kawasaki Z1s that he’s built by hand at home. Despite the fact that the bikes look every inch like long-lost Kawasaki prototypes, they were imagined by Allen and put together using parts from original 1974 Z1s. Sounds simple doesn’t it?

"Everything is a problem when you’re converting a four-cylinder crankshaft into a six-cylinder," Millyard told MCN. "All the balance weights were in the wrong places, so I had to re-engineer those.

"Then when I cut the crank cases all the studs were in the wrong place so I couldn’t just hang a cylinder on either end like I wanted to, although that’s sort of what I did do. I always run into problems; I just don’t dwell on them. I sort them and push through them."

Kawasaki Z1 Super Six engine

The extra cylinders are actually added in the middle of the new engine. A first engine is cut in half straight down the centre and then cylinders two and three are cut out of the second. These are put into the first to become cylinders three and four of the finished six-cylinder motor.

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Astonishingly, Allen doesn’t write things down or design anything on paper. "You have to three-dimensionally visualise the whole thing in one go and then fix all the problems at the same time."

And Allen’s imagination is obviously a very powerful place, as the first engine went from an idea to running in just six weeks. "The second one is significantly easier than the first. Whereas I had to dwell on something for a week the first time round I can just go straight through that process."

Kawasaki Z1 Super Six exhaust downpipes

"I’ve bought damaged engines and corroded engines of the correct year and refurbished them to make them look new, I tend to use the 70s stuff because it’s better. I wanted to keep it as original looking as possible so that from the side, you can’t tell it’s modified. So many people online think it’s a genuine bike and that’s properly cool when that happens."

Overall, the first bike took just 13 weeks to build using a restored Kawasaki Z1 900 and parts from two 890cc Z1 engines, giving a new capacity of 1355cc. The second bike will take longer to finish because Allen is taking his time with it but it uses the slightly larger 1015cc sleeves from a later Z1 engine giving a new capacity of 1522cc.

"It has got an electronic ignition, that’s the only upgrade I do fit. The original would have had points and coil and condensers and things but Boyer Bransden made me a really cool ignition system for it but that’s the only ‘modern’ thing I’ve got on there."

Kawasaki Z1 Super Six built in a shed

You might assume that figuring out a new firing order and crank arrangement would be a challenge when moving from four to six cylinders. "That’s easy," explains Allen, "I use a 120-degree crank so the middle cylinders are offset by 120, then the next two and then the outermost two. So you end up with a standard firing order."

Allen has to work out what that firing order is (1-4-2-6-3-5) for me because he says, "in my mind, it’s not a significant thing to worry about."

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Ben Clarke

By Ben Clarke

Staff Writer, hick for life, two cylinders max