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The Big One!

Alan Redgrave

Sometimes referred to as "CtC", a chain strain too far!  You've guessed it, the Yorkshire Section's Coast to Coast Run 2003.  What a great weekend, the first time the Shropshire Section had entered as a team, and the first time for Joyce and myself.  I won't go into detail about the run, but would like to relate an incident that occurred.

It happened on the Sunday, and as we left Alston, it started to rain, with thunder and lightning.  Joyce was up ahead on our 1976 orange Mobylette with variator, and I was on David Flye's 1960s Mobylette bringing up the rear.  About 2-3 miles out of the town, climbing steadily up the long drag, I saw a small yellow dot on the left hand side of the road.  "Oh, that's a shame" I thought, "someone's broken down already".  And then, through the swirling, howling Cumberland mists, I saw my dear Joyce, waving forlornly, and silhouetted by flashes of lightning.  I enquired "what have you done to it now ?" and then pure male instinct cut in as I dodged a solid right hander equalled only by Our 'enery Cooper.  The symptoms seemed to indicate a fuel blockage.  The plug and drive belt were new specially for the CtC.  So, off with its carb and a complete strip, dry and blow out, and all was well.  By the way, for those who know the Moby or Runabout engine unit, it was fitted with the earlier carburettor direct to the cylinder set up (with filter retaining clip), which is difficult at the best of times to remove and replace.  Urged on by verbal prodding from Team Salopia plus a constant drip of water down the back of my neck, the unit was re-fitted in record time.

Let's turn the engine by pedalling, and, hello, what's happened to the decompressor cable?  It's broken.  "Ah, yes," said Joyce, "that happened this morning, didn't I tell you?", backing it up with her best demure smile.  Come on now lads, you know you can't beat that, so I yielded to democratic persuasion and took the plug out, if only to look technical.  Team Salopia now had something constructive to do, so with pedals flailing and yours truly crouched over the cylinder head, we tried to establish if there was a spark at the electrodes.  Well, actually I saw two sparks, one of which was tracking along the plug's ceramic nose or central electrode, with the other an occasional sparkle from the plug body to the remnants of the decompressor cable.  (Old hands among you may be nodding your heads by now, knowing what is about to transpire.)  Pop in a different plug, and let's pedal down the hill.  Nothing!  Keep pedalling and try the lights.  Nothing!  The generator must still not be working then?  Push the bike back to the lay-by and check if the points have closed up.  They were OK at 15 thou.  Pedal down the hill again, if only for something to do, and for some silly reason I pressed the electric horn button.  Three things happened simultaneously; firstly the horn went "buurrrrp", secondly the engine started up, and thirdly Team Salopia cheered.  The first and second events had together told me what the fault was, but the third?  Just a minute, I forgot, push the bike up the hill and try telling Team Salopia that actually I hadn't repaired it yet was about to root amongst the wiring loom just behind the cylinder barrel.  Has anyone twigged the answer yet?

I was looking for a thin, braided earthing cable that runs from the engine pivot bolt at one end, up one of the two securing bolts for the external HT coil.  Why is this fitted?  Because the bike, as mentioned earlier, has a Variomatic unit.  This requires that the engine is pivotted at the cylinder head, which is supported by a long bolt passing through the rubber Metalastic type anti-vibration bushes.  There is also a rubber bush within the main variator return spring as well, making the engine unit completely electrically isolated from the frame.  This braided cable maintains electrical continuity for the low tension coils employed within the generator for both the lighting and ignition circuits.  (Note: the HT coil primary and secondary windings are self contained within the HT capsule unit and employ star washers on the two fixing bolts to complete that particular circuit to the steel of the frame.)  Sure enough, the braided cable was broken at the pivot bolt end, but judging by the amount of dirt around it, had been like this for some considerable time.  So, how had the earth return circuit been completed?  Remember the plug, which sparkled when touching the old decompressor cable?  This cable, in electrical terms, is connected directly to the engine at one end and directly to the frame via the handlebars at the other.  Why not the throttle or choke cables?  Because the carburettor is insulated thermally and electrically by a fibre gasket from the cylinder.  This is how I effected an 'out in the field' repair: by pulling out as much of the braided cable as possible and tying it in a granny knot around the head of the decompressor spring.  This got us to Whitehaven and to work, etc ,for the next few days until I made a new decompressor cable.

I've since put about 100 miles on the clock but haven't made a new earth cable yet.  There doesn't seem much point, as the old one was the original 1976 fitting.

First published, October 2003

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