Planning for machining the engine cases

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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.

Clock on…

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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!

Turning the Crank

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The end of the timing side needs a shoulder putting on it due to a design change. (Clearance for the sleeve drive chain links). In order to do this the crank assembly needs to be mounted and spun, which was quite a challenge! The conrod doesn’t clear the lathe bed so it’s been suspended from the ceiling with a bungee, to allow it to move but retain some tension. It’s a full sized turning crank that gives a good idea of what’s going on inside the motor, not something you see every day!!

Setup for checking runout

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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!

Patterns with style

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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.

Chain guard

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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!

Sleeve drive sprocket

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The sleeve drive sprocket has been drilled by Bob to allow for a vernier adjustment. The 9 holes allow the sprocket to be fitted to the timing shaft in a number of different positions.

With 22 teeth not being visible by 3, three mounting holes would allow the sprocket to be fitted three ways, each time a tooth ends up in a different relative position. To refine this further, three sets of three mounting holes have been drilled.

Why? Well during final assembly the valve timing will need to be set. This will be achieved by setting the piston at the point where a valve opens, moving the sleeve into the correct position and then bolting the sprocket to the timing shaft.

Sounds so easy when you say it!

Meanwhile…

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While Dave works on the patterns, a little job I’ve been meaning to get around to I finally got around to! The Kawasaki brakes seize monthly during the British winters. Government sponsored rust fairies abound when they put salt on the roads. Might as well be riding through the sea!

The brake pistons are steel which is hard chromed. Ok for a while but the chrome is thin and eventually flakes off. New pistons are pricey and don’t last more than a couple of seasons. I knocked up a pair in 303 stainless steel, which should last a long time! (Longer than the rest of the bike looking at it).

So the front is rebuild and the rears will go in this afternoon. The mighty KLR 650 will be back up and running for winter – if I ever get to go anywhere 😷πŸ₯ΆπŸ

A Pattern Maker

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Meet Dave. Dave swims like a fish, no, wait – that’s a 70’s government advice cartoon urging you to learn to swim.

Meet Dave, our new pattern maker. Dave cut his teeth making patterns for his apprenticeship, before branching out into wooden shoes. He’s fairly local and s biker too, so it all fits together nicely!

We’ve spent a few nights running through our project, the drawings and some patterns from other engines. Dave has suggested a few foundries to try around Leicestershire, so that’s next on the list.

It should take around 6 weeks give or take, so I could have a set of patterns in my hand for my Birthday. Or maybe, even, the castings!!