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Villiers 32A Electrics and Piston Clearance

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  • Villiers 32A Electrics and Piston Clearance

    I have now finished the rolling chassis of my 1964 TES so time to start on the motor/gearbox unit. This is a 32A with Greeves cylinder and head. It was purchased as a loosely assembled non runner so before I strip the engine too far I want to check what it wrong with it.

    Electrics
    As found the engine had no spark when turned over but after some fiddling and cleaning the points it has a fat spark, but it is yellow not blue.
    A meter on the wire from the ignition coil to the points gives 2.5 volts when the motor is turned over.
    The resistance from the wire when disconnected from the points is only 1.1 ohms.
    Is there a spec for these values as both these seem low?
    I assume a blue spark should be possible?

    Piston
    As found the engine has no compression but lifting the barrel off reveals no rings. The piston to bore clearance is given in the Villiers service book as 0.008 thou max. Mine measures 0.007 so in theory just in tolerance.
    What experience do others have with piston clearance as I would have thought 0.007 thou needs a rebore.
    Should the Greeves cylinder use a head gasket.
    Lastly the combustion chamber shape is only half the piston area. Should this chamber be at the front over the exhaust, or at the rear above the carb?

    I have hopefully attached a picture of the engine. This shows terminals on top which I assume are redundant if I am using the bike for trials only. Does anyone know what the peg is that is threaded into the cases just in front of the terminals?

    Thanks,

    Peter
    Attached Files

  • #2
    Pete The terminals shown are for lighting. The large one for Headlamp/Tailamp & the Small one a lower output for a stop light. Both are AC output.

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    • #3
      32A electrics and piston

      Hi Peter, a reading of 2.5 volts on primary coil is ok, mine only just about gets up to 2 volts but maybe your kick is a lot harder than mine. Sorry not got a figure for resistance of primary coil.
      Sounds like it will need reboring soon but why not put some rings on it and see what it goes like!
      The head should have a compression plate of 40 thou, the original was steel but Simon at Nametab made some from aluminium.
      The Cylinder head should have the spark plug which is off centre to the rear, so I was told many years ago. I have had it on both ways and it seemed to make no difference!
      The peg you mention is drilled and is meant to be a breather for the mag case but with such a small hole it cannot have done much....John P

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      • #4
        Electrics and Piston Clearance

        Thank you to both Johns for the replies.

        Does the Greeves barrel still use a head gasket as I assume the compression plate goes under the cylinder?

        Given trials in NZ includes creek work I might shorten the mag casing vent so I can fit a tube on it and run that up to a higher point on the bike.

        I have found some information on the oldlawnmowerclub.co.uk site dealing with Villiers engines. Using these numbers as a guide I will check both sides of the coil once I have it out. I have copied the article below in case it is helpful to someone else.
        Checking or Replacing The Ignition Coil
        If the engine is suffering from a weak (or no) spark, then the problem may be within the magneto coil. This can be checked using a voltmeter (to measure resistance) but it is required to remove the wire connection between the coil and the points.
        The primary winding should have a resistance of just a few Ohms (measured between ground - either end of the iron core - and the socket in to which the points wire was screwed.) The secondary winding resistance should be 3-5k Ohms and this can be measured between the side terminal connection to the H-T lead and ground.
        The most likely scenario with an old magneto coil is that it has some internal corrosion and the secondary winding (which is wound from extremely fine copper wire) has broken.
        Replacement coils can be sourced via the internet but ensure that you specify the correct length and end diameters as there are various models available. Replacements are not cheap (perhaps £50) and beware of untested items for sale on auction sites!
        Regards,
        Peter Barnett

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        • #5
          My 32a engined TFS has lighting coils in. I had problems with the original ht mag coil inside the engine, they fail when hot due to the aged insulation breaking down. I now run my bike with an external ignition coil fitted under the fuel tank. You can power it 2 ways. you can use the lighting coil which is 180 degrees opposite the ignition coil ( I cant remember which of the 2 lighting sockets on your engine goes to that coil, I did away with the sockets on my bike and soldered a longer wire to the lighting coil so it reached into where the points are). the other alternative is to remove the internal ignition coil, carefully strip the fine ht winding from the coil and refit, using the lt current to supply the external ignition coil. I have read that some people use this with the lighting coil wired in parallell to boost low speed spark, I havnt tried this yet but I have a reliable ignition system, hot or cold. The other sensible mod is to mount the condenser with the coil so that it does not break down due to the engine heat. I believe these mods were used by riders back in the 60s to overcome ignition problems. I got an external ignition coil from Villiers services for around £15.

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          • #6
            32A electrics and piston

            No, the compression plate goes between the head and the barrel. The base gasket is paper....John P

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            • #7
              Originally posted by floydbassman View Post
              you can use the lighting coil which is 180 degrees opposite the ignition coil ( I cant remember which of the 2 lighting sockets on your engine goes to that coil,.
              Its the small socket that provide 6 volt AC for a stop light if fitted.

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