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Mocyc/Motamite Notes - April 1993

by Derek Rayner

I have recently received a letter from a club member asking for help with his Motamite/Mocyc engines he has just purchased.  He quoted engine numbers of 5555, 50818 and 507164.  What has intrigued me for many a moon is the number sequence of these engines.  I can live with the straight forward four digit series such as mine (6861) and might presume that this started at some convenient round number like 5000 when the firm moved to Todmorden.  The earlier number sequence did not appear to have any sense to it; at least, not until I re-read the member's letter and looked at the way he had set the numbers out.  By a coincidence we are currently dealing at work with a firm that uses a computer-style identification reference for its correspondence and this currently is 93 02 xx.  It suddenly clicked with me, since the Motamite numbers had been written "50 8 18" and "50 7 164".  Bear in mind I had not seen these numbers actually stamped on the engines but it's the same sequence, ie: August 1950 and July 1950.  This principle can be applied to all the Motamite numbers I know about, excepting three, which can be put down to misreading errors.

Please, can all members who have not yet done so, advise me of their Mocyc and Motamite engine numbers and registration numbers so a more comprehensive list can be built up for the benefit of us all.

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Motamite/Mocyc Notes - June 1993

by Derek Rayner

Thank you to those members who responded to my request in the last issue regarding the provision of their engine numbers to enable Andrew Pattle and myself to assist other members in connection with building up a comprehensive register of existing machines and researching more details of them for the future.  Having produced a sequential list of known numbers, it may be of interest to other owners to learn that the total number of Motamite/Mocyc engines on it is just 38.  The lowest number known of the first series (Motamite) is 49 12 13 and the highest, 51 00049, although in this datable numbering sequence (see last issue), there is no apparent way of determining exactly how many engines were produced over the period in question.  For some of the months involved, none has survived, or was produced. In others, from surviving engine numbers, over 200 were produced, according to the highest number known (assuming they started at 1 again at the beginning of each month).

A conservative estimate of Motamites from this information is 1,068, although some confusion apparently exists in some quarters regarding the difference between Motamite engines and Mocycs

If we are to assume (until proved otherwise) that Mocyc engines started the revised numbering sequence at the time when the work was transferred from Bournemouth to Todmorden commencing at 5500 (a nice round number and away from the previous sequences to avoid confusion), then the lowest number in the four digit (Mocyc) sequence is 5537 and the highest is 7174.  It would appear therefore that the total Mocyc build may have been in the order of 1,700.

There are one or two anomalies that have become apparent as a result of this recent listing of the engine number details:

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Motamite/Mocyc Notes - April 2003

by Derek Langdon

I was pleased to see an article about the GYS or Cairns engine in the last Buzzing.  This engine is a particular favourite of mine.  When I acquired my engine it was dismantled, incomplete and minus fittings.  The con-rod had been bent and this had caused the gudgeon pin to work over to one side and score the cylinder bore very badly indeed.  Big and small ends (both bronze bushes) were badly worn, as were the mains.

Now the state of the cylinder bore was not a problem because I had a brand new Teagle cylinder liner which fitted with only a small amount of machining (William Teagle must have had a long hard look at the GYS before he designed his own engine.)  I straightened the con-rod and made new bushes.  I lapped the crank-pin to eliminate ovality.  The piston was fortunately OK, but I cut circlip grooves in it rather than rely on the soft end pads originally used to locate the gudgeon pin.

All time-consuming but straight forward so far.  Then came the interesting bit: the crankcase seals, or lack thereof.  As Colin King said in the last Buzzing, this area of the engine is perhaps somewhat lacking.  The original idea was that the crankshaft was supported in two ball bearings, one in the crankcase, and the other behind the magneto.  Between the crankcase side bearing and the drive roller is the sealing arrangement.  This is simply:

  1. the shaft runs in a very closely bored sleeve which is part of the crankcase door or side cover, and
  2. a felt seal in a cup washer on the outer end of this.

The trouble is that, when the main ballraces wear, the shaft starts to munch away at the sleeve and the sealing affect is lost.  The simple solution is to bore out the crankcase door to take a modern seal, there's plenty of metal to go at.  The felt can be retained to keep out grit.  I used a fully sealed bearing on the magneto side.  An extra oil hole in the big end and some hand fettling of the ports completed the internal work.  The drive roller was assembled with a rubber washer (old inner tube) at each end.

As I had no fittings, I used BMC Mini shock absorber end bushes for the engine pivot and new steel tubing and bits of old bed for the framework.  VW Golf front anti-roll bar end bushes served for the top fixings and more Mini bushes looked after the lower end mountings.

So, what does it go like?  On a pre-War Elswick sports bicycle, not badly, probably the mid to high twenties.  Its main virtue is its very flat power curve and very nice feel and sound.  On 16:1 petroil (in deference to the plain big end) it does rather tend to oil the machine and rider, and the odd wipe over of the front rim is a must if you want any braking.  It's quite light, and being front mounted at least you can see if anything falls off!

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