4 Stroke Allen scythe (Villiers MK25)

Just got this, may need some help with the engine ? - we will see

Hello and welcome!

A few of us on here have a soft spot for an old Villiers, I'm sure we'll be able to help.

Used to have one of those brutes!!  Scared the life out of me when I got it going.
Gave it to a mate to mow his wife's paddock.
Best of luck.

Woodsman wrote:Used to have one of those brutes!!  Scared the life out of me when I got it going.  
Gave it to a mate to mow his wife's paddock.
Best of luck.

Fiendish things, they tend to want to go round in circles as they only drive on one wheel! Our former club secretary was given one to use when he worked for Severn Trent, it got away from him and ended up in the River Derwent so he just left it there. It was recovered later and sent for scrap, a conventional mower replaced it!

Pete.

.... here is the engine plate, is there a way of dating the motor from this plate ? - what does the 15.01 signify after the Mark C25 ?



thanks for the help

The Villiers C25 engine was introduced in the early 1970's and continued in production until Villiers closed down.

I think the light green fuel tank on your Allen Scythe is not original, I think it may be a Norman engine tank.

I think 15.01 is the spec, different exhausts, air filters, pulleys ect would be fitted for different applications.

I have found a bit of time this morning and popped the flywheel off the Villiers Mk 25 in the new to me Allen Scythe - first surprise, hello it’s really clean in here, someone’s been here before - second surprise, can you see why it’s a non runner ?

Don't forget to put two steel pieces across the magnet poles of the flywheel while it's off, I used a couple of large Allen keys.

…. what should I run the Villiers mk25 four stroke on that is in my Allen Scythe ?, can it be unleaded ? - what are others using ?

Yes, unleaded is fine. You may want to drain the tank and and run the engine with the tap closed to empty the carb if it's going to be unused for while. There is talk of the new E10 petrol attacking older rubber seals, fuel pipe and even 'mazak' carb bodies, but how much of an actual issue it is I don't know.

I recently scrapped the cowling off a C25, it had an oval plate on covered in paint. When the paint was removed it revealed this:


Spec(?) No. the same as yours, so possibly off a scythe?


I still have the starter pulley cover if you are interested?

…. oowh, very interesting - that’s a bit later than mine, I did not know it had a cover over the pulley - I have the bit with round holes in, not sure it has holes for that bit ? - but I have seen a picture of one with it.

last night, looking on my phone I did not see that that is the same size as the bit I have, looking through its mesh on a proper screen I can see the round hole piece I have - I guess that the pulley cover I have has that cover bust off - so yes please if you are prepared to part with it it would complete my cowl - thanks Andy

Rowehillmaster wrote:  last night, looking on my phone I did not see that that is the same size as the bit I have, looking through its mesh on a proper screen I can see the round hole piece I have - I guess that the pulley cover I have has that cover bust off - so yes please if you are prepared to part with it it would complete my cowl - thanks Andy

You have a PM.

I have been looking at my lack of spark - it goes deeper …. the wire from the coil to the points, should only go to ground when the points are closed - correct ? - well it goes to ground even with the points disconnected, is the coil knacked?

I don't understand magneto systems too well. For example I made up a battery and trembler system for an old Briggs and Stratton on a Hayterette, I used the original points to switch on the trembler, as the recoil starter was broken, I used a cordless drill to start it. I've used it a few times, but was never happy with the starting (it tries to kick back). I now find that the contacts close at 47degr. btdc and open at 30dgr. btdc. My spark starts 17 degrees early.
That was just to illustrate that I don't know what I'm doing.

But if you have a condenser under that cover; it might be worth disconnecting it and checking that it is not short circuited.

Rowehillmaster wrote:I have been looking at my lack of spark - it goes deeper …. the wire from the coil to the points, should only go to ground when the points are closed - correct ? - well it goes to ground even with the points disconnected, is the coil knacked?

As oldgit says, worth checking the condenser, it's in the back of the points housing. You have to remove the housing from the backplate to access it. Another possibility, if someone has been messing with it, is the points have been assembled incorrectly with the insulating washer in the wrong place or not fitted. The villiers mag is different to any other points set up I've come across (on old cars) in that the it's the moving contact that's earthed, rather than the fixed one. Other than that, I would say that it is possible that the coil has a dead short to earth.

I have a PDF of the MK20 and 25 manual (same set up) which has an exploded view of the mag/points set up, it's not the clearest but you are welcome to a copy if you PM me your email address.

Tricky to test coil in situ. As Matt says there could be a short anywhere. Do you have a connection to a 'kill switch' through the backplate? Insulation sometimes missing/frayed.
Best to disassemble and test the coil stand-alone. It's usually the HT side that fails open circuit.. Unless you have a low ohm meter the LT side may appear short circuit.

….. things have progressed this afternoon - I have completely dismantled the magneto removing the back plate from the engine (thumbs up to my old impact driver ) and with the coil out it tests exactly (figures in the region of +/- 20) to that of info I have searched out on the web, so it would appear not to be the coil. I have completely dismantled the points, cleaned and reassembled them and testing them on the bench all is good with no path to earth on the points connector with the points open - I am going to rewire the coil next, we will see if I have cured it ?
Thanks Andy

I have rewired the coil, reassembled everything and put the the magneto backplate back onto the engine block, I put the flywheel back on and it won’t turn a full 360 ! - the magnets are hitting the stator pieces that the coil fits between, with a big clunk   - what have I done wrong ? ( it looks like it has happened before as upon examination the stator pieces are worn  - any suggestions ? - incorrect assembly does not seem to be possible, the coil holding holes are at the top and this makes them handed, plus the screw holes are only countersunk on one side

That's a strange one, the only thing I can think of is play in the main bearing that side.

 - I looked at it tonight, magnet was hitting the top left ear of the stator plates that hold the coil - I removed the magneto back plate, disassembled and reassembled the coil stator plates with a south easterly pressure applied, tightening the offending corner first - reassembled everything, and once the magneto flywheel was on it span smoothly with no clunk - I static timed it and set the points gap - added the pull start ring and clamped the HT lead to the block so the terminal was close - just positioning the pull start ready to wind I saw a faint spark - with a good pull it sparked away like lightening - it will live - tolerances are obviously loose !

Good to hear you now have a spark

The coil poles to flywheel gap should only be about 10 - 12 thou so everything has to be in the right place to avoid contact.

It has ran briefly on neat fuel down the hole, just had to hear it run before I started stripping the carb etc.

A new phase of my restoration begins, fed up with grovelling on the floor to adjust the timing I have dug out the motorcycle bench that my grandfather got from a GPO sale in the 70’s (I knew it was worth keeping ) - just the job