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Identify these bikes! / Re: Villiers stationairy engine
« Last post by Albion EJ on Today at 04:00:31 PM »
Thanks again!

Sorry I misunderstood the preference of an alloy piston compared to a cast iron.

What is in your view the biggest advantage of having an alloy?

Indeed I also have cast iron ones found only so far.
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Identify these bikes! / Re: Villiers stationairy engine
« Last post by 33d6 on Today at 08:18:04 AM »
Can’t help with the second Mk XII-C engine. My information is based on records of unique Australian motorcycles, not all motorcycle makes. In general most of these minor makes started to appear here in the mid thirties and quickly disappeared when war was declared. None survived WWII. Numbers start around the 6500  and end around 11000 in 1940.
Calculating the Villiers engine approximate year of production from these records was a serendipitous by product of other efforts. It was not my intention nor as I keep saying, does it serve any practical purpose.

As far as your engine stands it is what in my apprenticeship days we called a ‘short’ engine. Not a complete unit and would be used as an exchange, refitting all the essential fuel, ignition and drive components already present from the receiving machine. On its own it is only one sub assembly of a Villiers power unit.

Curiously, the Mk XII-C cast iron piston is well catered for. F W Thornton of Shrewsbury list all sizes and oversizes on their website. It’s only the favoured alloy versions that are hard to find. It seems I’m not the only one to choose alloy pistons over cast iron. Its not a genius decision.
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Identify these bikes! / Re: Villiers stationairy engine
« Last post by cardan on May 11, 2025, 07:49:17 PM »
I'm no expert, but I think the XII-C was introduced in about 1931, and this one might be c1933? No doubt 33d6 can be more authoritative. As i mentioned above, start dates are useful, but it's more interesting to know for how long a particular style of engine was built and used... Always interesting to see an engine like this in its original bike, so that the bike dates the engine rather than vice-versa.

Leon
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Identify these bikes! / Re: Villiers stationairy engine
« Last post by Albion EJ on May 11, 2025, 03:28:35 PM »
Would you be able to date this engine as well?

I do have a used cast iron piston at 54mm without rings which is for sale.
Please drop me a message including an offer.
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Identify these bikes! / Re: Villiers stationairy engine
« Last post by 33d6 on May 08, 2025, 02:03:22 AM »
The Mk XII-C & XV-C engines show a lot of potential but suffer a major handicap. There was never an alternative alloy piston for them. To repeat myself yet again, replacing the original cast iron piston with an alloy version transforms these basic Villiers engines. The alloy 25C piston drops straight into the VIII-C, the 196 Super Sport into the 1E & 2E plus several aftermarket piston firms made an alloy version for the original 175 Sport but there is nothing for the XII-C/XV-C. (The XV-C is the single exhaust port version of the XII-C).

The XII-C  has the best breathing of all the pre-war C series. It sports the MW carburettor, the same size as used on the earlier 175’s and the 196’s of its time and Villiers made an appropriate exhaust for it but the times were against it. Two-strokes were looked down upon, fashion decreed a Brooklands flavoured exhaust system and four -strokes were de rigueur.  No one was interested in them.

Nowadays we see the potential for a tongue-in-cheek fun little bike but it’s too late for riders with average finances. Financing small batch piston manufacture is a bit beyond us. Pity about that. So close yet so far.
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Identify these bikes! / Re: Villiers stationairy engine
« Last post by Albion EJ on May 07, 2025, 01:39:37 PM »
Thanks all!

I already noticed these paired numbers.
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Identify these bikes! / Re: Villiers stationairy engine
« Last post by Rex on May 07, 2025, 01:08:40 PM »
Brass would have been considerably dearer than other alloys when demand was high due to rearmament.
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Identify these bikes! / Re: Villiers stationairy engine
« Last post by 33d6 on May 07, 2025, 11:35:06 AM »
Villiers made no distinction between any of the metals used in their flywheel magneto’s. What sort of aluminium alloy it is I have no idea. It certainly made no difference to performance. Personally I suspect them to be more of a zinc/aluminium alloy rather than straight aluminium. Although I’ve never weighed one they don’t feel any lighter. I suspect Villiers were just after a cheaper non-magnetic material for their flywheels and eventually concluded that it was simpler and easier to continue with brass. There’s certainly no logic to fitting a lightweight flywheel to a basic “cooking” model XII-C is there.
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Identify these bikes! / Re: Villiers stationairy engine
« Last post by R on May 07, 2025, 10:00:51 AM »
is there a picture anywhere of these aluminium flywheels.
Are they lighter than the brass ones ?

Do we know why they came about ...
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Identify these bikes! / Re: Villiers stationairy engine
« Last post by 33d6 on May 07, 2025, 09:43:28 AM »
The first registrations I have around the GY 7000 mark date around the first half of 1936. Can’t get much closer than that. As I wrote earlier I can only broadly date when an engine was produced from registration dates. The registration dates are surprisingly varied, there can be a several month difference between consecutive engine numbers. It is very broad brush. Not that it matters that much as Villiers didn’t make annual model changes and the actual date of manufacture is irrelevant for maintenance and repair purposes.

As for the aluminium flywheel magnetoes yes, Villiers made them alongside the brass variety. Again, it’s not really relevant detail for maintenance or repair so I take little notice. Of far more interest are the paired numbers on flywheel and backplate to ensure you have a factory pair. Mix’n’match can cause problems here.
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