Patterns coming along


Dave dropped round with one half of the patterns to show us the progress. Not far off being finished, the fillets, radii and draught angles are going in ok. The timing cover needs a second coat of paint and the main casing a full paint, but another week or two and they’ll be ready to take to the foundry.

I took the opportunity to pair them up with a barrel and for the first time the final dimensions are apparent. Bit of a lump but I can make it work. If the casting isn’t too pricy I’ll have two sets cast, and use the spare set and barrel for dimensioning the frame. The frame builders will appreciate a full sized engine to work with.

With all this activity going on, I need to start thinking about ignition and a carb. Neither of these are particularly challenging, I just haven’t put a great deal of thought in just yet.

Oof – get in!


With restrictions easing and a week off work, I was able to take up a very kind offer from Gary Stead at Stead and Wilkins ( They have some serious kit there, and amongst it all is a 100 Ton hydraulic press. Gary allowed me to use the press, which made light work of pressing the crank together.

A guy called George helped cart the heavy components across the yard, and operated the press after I’d set up the blocks. All done in about 10 minutes! Gary then showed me around the workshop, which was impressive to say the least. What a pity they’re so far for Leicester!

Definitely a company to keep in touch with, very capable and nice people. Biscuits are on me!

Gearbox jig


It’s been a cold few weeks and busy at work recent, so shed time has been limited. I finally got a couple of hours in yesterday and set about furnishing the mounting plate for a gearbox jig.

I want to be able to spin the torque converter and see what readings I get from the sensors on the box. I also want to check the direction of rotation as I have a nasty feeling it’ll be opposite to what I want.

I have a few old sets of sprockets from the mighty KLR650, a byproduct of all those miles I’ve put on it. So i have a borrowed electric motor spinning a rear sprocket, driving through an adapter plate I’ve just welded up. I’ve had no training on how to weld, but it looks pretty good in my book. I’m happy with that!

Patten maker’s rule – ok?


Had a update and set of patterns from the pattern maker Dave. They’re very good but not finished, no radii, draft angles or fillets yet. Changes now will be easy to accommodate, but after the radii and fillets are added much less so.

We’re having a good measure this week, returning the patterns once we’re happy for the final finishing. Within a couple of weeks we could have the finished items!

In the meantime, check out this patter maker’s rule. It over reads by 1 in 77, to allow for contraction of the metal on cooling. So the pattern can be measured and the measurements compared with the drawing, without any conversion. Very neat!

Best no leave that lying around, it would cause havock!!

Sleeve Drive Final Assembly


Here’s the final assembly of the sleeve drive crank, sprocket and drive pin. Finally looking like a proper engine component! The three holes in the sprocket are to allow it to be removed, rotated 120° and refitted. With the 44 teeth not being divisible by 3, this provides a finer valve timing adjustment than jumping a whole tooth.

Until the patterns arrive that’s all of the machining completed. Time to look at that gearbox and decide whether I can make it work for me.

Casting couch


While I was looking at Faceache on the couch, a good friend of mine Matt was busy with his home made furnace. It took a few goes and a couple of blown elements, but after a few days rough cast part arrived outside the garage.

The mighty KLR650 that took me all round the world had took the hump going up and down the Coventry Easterm Bypass. Who could blame it, given the wonders it has seen only to end up in such a miserable shithole. In winter. 😦

Anyway, the linkage under the swinging arm had seized solid. I had to cut it out and it cracked as a result. Mr. Kawasaki wants £160 for a new one. Plus £140 for a set of needle roller bearings. Plus £48 for a new spindle. And Mr. Uk Taxman wants his 20% VAT.

In an attempt to see what I can do for free with the tat lying around, Matt offered to have a go at casting a new one using the original as a pattern. This was an excellent start! His persistence paid off while I was still sat on the couch. Now known as the casting couch 😉

Sleeve drive setup complete


Here’s the final sleeve drive assembly, complete with chain tensioner in situ. The distance between centres is as drawn, with the adjuster fully in to give the full travel as the chain wears. Shown in the orientation it will take in the engine on final assembly.

It looks right and with the 9 holes (3 sets of vernier adjustment) we can get to within a single degree of timing. Spot on!

The valve timing needs some thought still as the Hercules was supercharged, so the inlet opens late. Static timing can be set with the drive sprockets, however, the relative timing between inlet and exhaust can only be changed by re-shaping the holes in the sleeve. I only have one sleeve so that’s a one way operation.

How much is too much? You will only find that out after you’ve done it and there’s no going back. Hmmm..

Test bench.


So my trusty bench is going to become a test bench, for real! Nick asked whether the new gearbox would fit on the Churchill lathe. His idea is to make the control electronics and troubleshoot now, rather than when it’s all together in the bike frame. Makes sense to me.

However, while it’ll just about fit (the Churchill has a 12" throw) I don’t want to tie up such a useful machine for any length of time. A quick call to Matt and a spare motor was dropped round a few minutes later! Got to love having a good engineering mates community:-)

The motor is flange mounted and happens to rotate the same way that the engine will. So, with a bit if cobbling around I should be able to make a test bench and drive the torque converter (Tc). The first thing I will be able to uncover is the direction the Tc is designed to rotate! I have a sneaking suspicion that it’s the ‘wrong’ way, i.e. opposite to the engine. Time will tell…

Sleeve drive centres final adjustment.


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.