The sleeve drive sprockets are machined up and the chain fitted. The distance between centres is critical and the chain length dictates that. The distance we’re chasing is 7 inches, which the chain adjuster helps – but the critical distance unfortunately falls between links.

The engine cases will need to be bored for the bearings, so the centres can be moved to provide a small offset. However, changing the centre of the sleeve drive crank will change (raise in this case) the maximum height of the sleeve. This in turn means that the barrel will need to be raised, lowering the compression ratio.

Important to nail this now before machining the cases. I think a maximum of .1" will bring the chain length, tension and adjustment within acceptable limits.

I picked up a gearbox for the project and now have a whole series of fresh challenges! The Toyota iQ box is a novel CVT, with an ECU ensuring the pulleys extend between four fixed ratios. The effect is like a 4 speed automatic, but achieved without any actual gears.

I could have taken the easy option of using a standard clutch and a brit bike or Harley box. However, if I did that anyone looking would recognize it straight away. The idea is that you look at the engine and wonder what the hell it is, and wherever else you look there are no more clues!

The fluid flywheel (on the other side) means the whole assembly is there, ready to rock. I just have to figure out how to drive it, and knock up some electronics. Easy right?? Hmm…

Planning in case??

We’ve petty much finished all of the steel components now, so Bob has been busy mulling over how we’re going to tackle machining the engine cases. While I’ve been reviewing the hand written notes and scratching my head!

It does make sense and doesn’t seem too onerous either. I just hope the patterns don’t take too long, as they’re holding us up.

Looking at transmission and after a good catchup with an old friend I’ve decided to go fully automatic. Modern small cars with CVT transmission have compact boxes presenting many options. I like the idea of not having a clutch level and cable, it will clean up the bars nicely.

Setup for measuring the runout on the drive side. Currently out by 20 Thou, but not fully pressed home yet. Once I’ve located a large press and finished squeezing them together, the operation can be repeated and the wheels trued.

In many Brit bike factories the truing up process was done by dropping one end of the flywheel assembly onto wooden blocks. The momentum of the other flywheel would tweak it round slightly. This weighs over 50kgs so we’re having a re-think on that one!

When the crank has been finally pressed together, we’ll need to check the run out. Ideally this will be zero, but is something that must be checked if longevity is going to be achieved! (And I do plan on the engine lasting!).

Minor runout could be adjusted with subtle use of a mallet, or for anything more serious machining one shaft. Or even making an eccentric sleeve. But hopefully none of these will be required.

The idea of the v blocks is to mount the whole crank assembly in the bearings on the timing side. The lot can be spun by the conrod and a clock on the other side measures any runout. Easy!

Should look great when it’s cast in Ally.

Dave popped round with a set of patterns he’d modified to be more in keeping with the barrel. Achieving a good look aesthetically isn’t something every pattern maker would necessarily think about. Dave’s time as a model shoe maker and designer really shows.

I like what he has done as an example and now we’re cracking on with the main items. I expect it’ll take 3-4 weeks to get something we can drop onto the drawings, then filleting and artistic flare to finish off. A bit longer than the original time estimates, but hopefully ready for casting before too long.

The sleeve drive will be a duplex chain, and like all chains it needs tensioning. Like old Notions the tensioner is ally, which Bob has made a great job of carving out of some leftover billet. It’s a lovely looking thing, the sort of artifact you’d pick out at an autojumble just because.

Shame no one will see it when it’s in situ! Apart from the 44T sprocket, all of the steel components are finished. Time to give Dave a nudge about finishing those patterns!