Taking a grinder to Britain's motorcycling heritage.
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Monday, 24 January 2011

A Slight Delay

Didn't get any further with freeing up the Drive Side big-end yesterday, so the rods are going away for a touch of remedial therapy. I'll get both honed to try and maintain the balance between the two. The comment by Billy Whiz on yesterday's post shows that it is a known problem. This is backed up by the fact that big-end honing is offered as an engineering service by SRM.

Decided to fit the crank into the cases anyway, just to ensure there are no nasty surprises there when the rods come back. They went together well and the new bush appears to be as good as it looks, so that's a result.

The cases are only nipped up as can be seen, but the crank spins freely enough to say "The jobs a good'un!". There's still plenty to be getting on with whist we're waiting for the rods to be sorted, so the time will not be idle. The gearbox needs looking at, or checking over at least, the head needs to be cleaned, painted and reassembled and the rockers and spindles need to be stripped out and built up in the NOS rocker boxes.

If you open this picture up and look just to the left centre of the chain tensioner studs, in the middle of the primary inner, you will see a number stamped there. This says 20-1-54, and it has been done with stamps in a proper holder and not individually stamped by hand. The engine number shows the motor to be 1948, I think this later date indicates that the motor had been back to the factory for a rebuild at that time. There is also a small letter "A" beneath the main engine number, again mysterious, but perhaps there to externally show that the motor had been rebuilt by the factory.


  1. tool stamped by a "fount" set.........
    tool man me

  2. I think what I would say is (to reiterate).. Don't rely on getting the shells circular in the rods by honing, because when tightened the tendancy is for the soft shells to follow the form of the rod big end "hole" - it's this hole needs to be circular - I bet you'd gathered that of course but when you said "honed" I started to worry (I'm a worrier you see....) ;)
    "Billy the engineer" (- yeah, right!)