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Andy, fully concur, if all the components in a magneto coil, points, condenser set up are good. Then so is the spark. Angus Shapland concluded that a Meco transistorized unit was not superior to a good points system. He liked them because it got rid of the condenser and after he had serviced a machine with points for a customer. It was then laid up for a while in damp conditions and when brought out again, would not start. The customer moaned, but he found all that was wrong was corrosion on the points. The Meco unit eliminated that problem, it was ‘fit and forget’. Have a Gravely L with a Bosch mag, a Trusty with a Jap 6 with a Wipac CJ mag and a Hayter Condor with a Kohler K181 with a flywheel mag. To all three, after a light hone of the points and resetting achieved a spark at 6mm. Left the original condensers in place and they all started easily and tickover is smooth. As an experiment I replaced the condenser on both the Gravely and the Kohler with a polyester film capacitors, there was no improvement. But I also have engines that could not attain a spark at 6mm, but would at 4mm. The coil tested fine, the points were clean and set up correctly. Starting was difficult and tickover erratic. This was especially a problem with manoeuvring a Trusty in tight spaces. The mags were Wico Series A’s, spark was 4mm, one had a condensor that failed a megger 500v test of a 200M ohms requirement, the other passed it. Fitted capacitors and both mags sparked at a 6mm gap. The improvement in the overall machine’s performance was remarkable. Have had transistorized ignition modules on engines that are difficult to start. The spark gap was 4mm or less, even though the coil passed a manufacturer resistance test. I replaced the module with cheap non-OEM ones and the spark exceeded 6mm, the engine was fixed. But I digress (hugely).

Back to David’s flywheel and I have another idea. If the hub HAS to come off, try using a 4” thin blade on a disc cutter with a longitudinal cut. From the replacement flywheel calculate the depth of cut that would be just touching the crank at any given point on the hub. Where the radius of the disc limits the cut near the armature plate, drill 1/8” holes at ¼” centres, then enlarge them with a ¼” bit. With feeler gauges measure the gap in the cut, put some steel wedges (chisels or screwdrivers) in the cut and tap tight. Measure the cut gap again to see if its parting. Try to remove the hub with a puller, if this initially fails, apply some heat to the hub. Still no go, do a similar cut on the opposite side of the hub. If that still fails, go down the pub to drown your sorrows and curse the time you ever contemplated messing around with a knackered old piece of machinery. If its any consolation, I’ve been there many times.

Grahame

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Thanks Andy, I did not know that. Have never worked on the close cousins of the Mk 25c. Have become a bit anal about magneto ignition. For years I subscribed to a school of thought that if engine had compression, fuel and a spark from a plug resting on ground. It should go. If the spark was blue and fat, as opposed to weak and yellow, all the better. But after reading technical information from Brightsparks, speaking to the owner and trying one of their capacitors. I realized that not only was the plug spark test no real test at all. But how an apparently good magneto could be greatly improved with a top performing condenser, or a modern capacitor. I now have a golden rule that if I cannot get a 6mm air gap spark, I work on the ignition system until I do. The difference in engine starting and tickover between a 4mm air gap and 6mm one is remarkable.

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Wish to correct and clarify what I posted yesterday about changing a magneto flywheel. I said it was just the cam lobe and magnet position that was important. Upon reflection, this was misleading, there are other factors too. Including: coil position on the armature plate, magnet to coil air gap and points cam feet position. Everything has to operate in complete synchrony for a good spark to occur at the correct time for the engine.

If the part number is the same on different Villiers model’s flywheel, then they should be interchangeable. But if the part number is not the same, then there is a risk it will not work, or even fit. Of course none of this will matter if David is going to use the Kettering ignition system. As long as the points open at the correct time for the engine. At a push, could even get away with not using the flywheel rim. Modern two stroke motorcycles do not have them. But the engine will sound like a motocrosser when in work and is more likely to stall.

Am going to see if my potentiometer is going to work at the weekend. Have a 14.4v drill battery that is reading 18v. If its successful, will post it, because it will be an easy and cheap way of powering a total loss battery system. Most folks have a battery drill and charger.

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Hi Dave,

Personally I would do the easy and/or cheap options first. If the multimeter tests are within the range indicated and the points are clean and correctly adjusted. But there is still no, or just a very weak spark. Suspect the condenser and as you say, you can fit one externally. Only fit new, not second hand or NOS. Would enquire at Villersparts if their square type is a modern capacitor and if so get one, or one from Brightsparks, or a 630v 220nF / 0.22uF capacitor locally. If the coil appears OK, but access to the points is so poor you cannot do the degree of work required to get them in good condition. Would fit an externally mounted Meco or Nova ignition unit. Angus Shapland (aka wristpin) has fitted lots on Villiers Mk25c’s and speaks highly of them. It appears the only problem with them is the voltage induced by the flux reversal has to be high enough to trigger the module. It is suggested 3v is needed, so the flywheel needs a bit of a spin. If the primary coil is poor, or there is a short in the circuit, then this may not be enough.

If the coil is duff, then things get a lot more difficult. You could as you say, make up a total loss Kettering ignition system and leave the points in place. However, I would firstly check the timing which should be 5/32” BTDC. If someone was so hamfisted as to overtighten the captive nut, I would not trust them to get the timing correct either. Would be great if you could get the screws undo that hold the brass flywheel onto the hub. But if you could do that, I am presuming you could access the coil and points sufficiently to remove them if required. Then am not sure if fitting the flywheel you have got from ebay will be of any benefit. Other than because you have damaged beyond repair the original when you removed it. If you are still going for the total loss ignition system, then if the magnet is in the incorrect position on the flywheel, it will make no difference. Would be surprised if the magnet was not aligned with the points cam lobe anyway. When the magnet passes over the soft core of the coil and flux reversal occurs, the voltage to the primary jumps. It is at that instant the points open, current ceases to flow through the primary (a good condenser is needed), the resulting collapse of the magnetic field induces very high voltage in the secondary which seeks a route to ground. So the lobe on the flywheel has to be synchronized to the position of the magnet on the rim. As the Mk25c does not have a keyway, you can adjust the timing. A problem that could occur in swapping the flywheels of different models could be the difference in magnet length and cam lobe profile.

If import duties and carriage from the UK are prohibitive. You could always try the single wire energy transfer system I posted on the 9th February. You will still need the 6v motorcycle coil for the Kettering system. The only extra would be 100g of 22swg enamelled wire and the time it would take to strip and then rewind the coil. For the total loss system you will need a battery and the time it takes to make a mounting for it. The coil, wire or battery could all be sourced in France. Am thinking of making a bit of test equipment with the battery I use in a cordless drill and fitting a potentiometer to regulate the voltage.

Lots of choices, but think you have settled on a course of action. Wish you the best of luck and keep us posted to how you get on.

Grahame

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Heat is one of the best spanners in the toolkit of anyone messing about with old stuff. Got the method of removing a Briggs & Stratton flywheel from multiple American YouTube videos. They put a wedge opposite the cylinder and a pry bar next to the barrel. Put the point of small air chisel on the end of the crank, pull the trigger and give the pry bar a yank at the same time and off they pop. BUT I have been lucky enough in never having to deal with a stuck one. Do have a slide hammer puller that gets most things off. If in the initial effort it does not move, or even seized nut, I very quickly resort to the blow torch.

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Thats a good idea, had not thought of that. A method I use to remove Briggs & Stratton flywheels is to put some wedges between the flywheel and the armature plate. Get a compressed air chisel, fit a point to it, place it in the centre of the crankshaft and pull the trigger. Never feel comfortable doing it though, armature plates are thin aluminium and always worry I could fracture it. Maybe with the Villiers it could be possible to suspend the engine ¼” off the floor, drive end down, with three of blocks of wood from the floor to the armature plate. So the engines weight is on the armature plate. Fit a packer between the cylinder barrel and the armature plate, put the wedges directly opposite the wood blocks and packer. Apply some heat to the flywheel centre and give the air chisel a go.

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Hi Dave,

Had another idea that may solve your problem. If the HT and LT continuity tests are fine, you could fit an external Meco transistor ignition unit. If you can get to the wire terminal on the hot side of the points, you could disconnect them and connect with a wire fed from the Meco unit though the back of the armature plate. The Meco module dispenses with the points and condenser. It works by ‘sensing’ flux reversal when the flywheel magnet passes from north to south over the coil’s soft iron core. This is when the points would start to open, the Meco unit has a transistor that does the same action. Namely stopping the flow of electric current to the primary windings. Because this action is so much faster, the collapse in the magnetic field is quicker too, resulting in a bigger spark at the plug.

The above is the theory, I have not fitting one myself. Although I had a duff coil on a Briggs & Stratton, it had a points system. I replaced it with a new modern ignition module and the spark exceeded the 6mm gap I like to achieve. Have tested other engines for spark gaps with these modules and >6mm is the norm. The Meco is available on ebay at £10.09p and for that money, it may be worth a punt. Have both a Villiers Mk25c on the Clifford and a Jap 2a on a Colwood that I have not used for a couple of years. Will get them out this spring and test the spark gap, if <6mm will fit a Meco unit just out of curiosity.

To test your coil with a multimeter, ground the black lead, set to 20K and put the red probe in the plug cap to test for HT continuity. For the primary coil, set to 200, put the probes together and note the reading, it may be a fraction of an ohm. Disconnect the points and put the red probe on the wire that goes to the coil. From the reading, deduct the figure that was noted with the probes together.

Another test that I have not personally done is to get a 6v or 9v battery. Set up a spark tester, or if you cannot get hold of one. Remove the earthing electrode from an old spark plug, if this sparks the gap is about 4mm. Clip a wire from the negative terminal on the battery to the armature plate, ensure the points are closed and with a probe from the positive battery terminal, quickly tap the screw on the points that retains the terminal for the wire that goes to the coil. This test ‘loads up’ the coil so is a test that better replicates performance when the engine is rotating. But I would still do the multimeter test first, its recommended by engine manufactures, including Villiers.

Of course even by fitting the Meco unit, the flywheel will still be stuck on the crankshaft and you will still have the same problem if the coil fails. You could do as you suggested originally and try to get the points serviceable with the flywheel in place. Then mount an external battery, coil and condenser. To get the flywheel off you may try to adapt an existing three bolt puller and tap holes in the flywheel spokes. If you do get it off, you could reuse it by turning the nut retaining section and using a new nut on the crankshaft. Or if a replacement flywheel is readily available, cut if off like Andy says.

Grahame

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Hi Dave,

When undoing the flywheel nut, there is a few turns when the nut feels free, where it transitions between tightening onto the crankshaft and starting to pull the flywheel off the taper. It then goes tight again and if you continue to turn or hit the spanner, it almost has the feel of a thread stripping. But it is just the action of the flywheel pulling off the taper. If the nut turns free for several turns but the flywheel is still firmly on the crankshaft. Then you will have stripped a thread and would hope its not on the crankshaft.

Have read with interest your ideas about fitting and external coil and battery. About 14 years ago I purchased a Clifford Mk1 that was in great condition, except there was no spark. The vendor was very up front about it and said he thought the coil was duff. He said it may be possible to fit an external single wire energy transfer coil, similar to a Honda C50. He was right about the failed coil, so did some research and decided to have a go. The system was developed by trials riders in the 1960’s, whose Villiers engines had reliability problems. They stripped the secondary windings off the ignition coils, linked the primary with the lighting coil and fitted a 6v external coil. Without a lighting coil, I just stripped the secondary windings and attached the single wire to the external coil to the hot side of the points. No spark, so gave up on the idea and got a replacement from Villiersparts. It was not an exact copy and needed a bit of work to fit. But the results were a good fat spark.

I now know why my attempt of fitting an external coil did not work. The voltage generated by the primary winding was not enough to induce a spark. It is why the 1960’s conversion used two coil windings. In an ideal world the ratio of primary to secondary windings should be 1:10. The method I should have done was to strip the coil completely and rewind the primary using 22swg enamelled wire, putting 350-400 turns on the soft iron core. Still have the external coil, it was I recall only £12 and have vouched that the next time I have a duff coil. I am going to have another go at fitting it. The advantage being that the voltage generated by the primary will create stronger lines of magnetic force within the secondary. At the moment of flux reversal and when the points open, the magnetic field rapidly collapses. The voltage produced will be greater, therefore a bigger spark at the plug.

However, all of the above may be superfluous to you. Once you get the flywheel off, you may just clean and adjust the points and job done. I like to obtain a spark at 6mm air gap and use a cheap adjustable spark tester for this. 4mm is OK, it will run, but starting and tickover is better with the greater gap. If no or weak spark, then get a multimeter and test resistance. HT continuity should be 3000 – 7000 ohms and LT 0.5 – 0.7 ohms. If you are inside these ranges but still no or a weak spark, then in all likelihood the coil is OK, but the condenser if duff. This can be tested, but will need a megger to check the insulation resistance is 200M ohms. Its probably better to replace it and I would fit a modern capacitor. I fitted one from Brightsparks with fantastic results, all of the above test figures and methodology I obtained from them too. They have a brilliant website that goes into magneto ignition in great detail. Note that Villiersparts sell a modern condenser, but do not know its specification. Subsequently I have got some polyester film 630v 220nF/0.22uF capacitors and fitted those. Again with brilliant results.

Best of luck with everything.

Grahame

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Another way of getting bearings that I have done many times is to get one from one of the large online suppliers. I have used Bearing Boys and Simply Bearings. If the bearing has a manufacturer and a reference number on it. You can cross reference it with the company’s lists. If not, measure the OD, ID and width and put that in the company search engine. You will need to determine if the bearing is metric or imperial first though. A 1989 machine may have either size as it was in the middle of a period when the sizes changed. The balance of probailities is that Hayter used a stock bearing that is still readily available. But would firstly take advantage of David’s kind offer, he has vast experience in these matters.

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If originality or you get the understandable satisfaction from doing a repair to the existing tap. Then you can carry on doing it with the care you have taken to date.

Personally I would replace it even it just to save the time and the trouble of fixing the old one. I am more interested in functionality that originality. Expect the thread into the tank would be BSP, it likely to be either 1/8” having a 0.383” diameter and 28 TPI. Or 1/4” with 0.518” diameter and 19 TPI. The fuel pipe is most probably 1/4” bore. Would fit a small in line filter too. There are loads of different petrol taps that would fit. Again personally would not fit an Ewarts cork one from choice. Find they often leak. But have replaced the cork with some O rings and that seems to offer a good seal.

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David,

Hugely impressed with the machining you can do. Have a mate who is very elderly who can do similar. Know it takes a massive amount of skill, experience and time to produce such items.

Grahame

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Dear Charlie,

A big thank you for this. Have no idea if Clifford copied the Simar design, would be interested to know. But expect they would have used typical 1930’s engineering methods that would have included leather and felt oil seals. From the parts diagram and list can see the Simar has both. Once removed from the machine, would be a simple job to cross reference them with modern seals to see if one would fit. Failing that, I was going to use some neoprene sheet material.

Do you know of the spring tines on the Clifford are the same as the Simar’s. It was about 35 years ago when I contacted Chester Hudson who had them in stock. There was some discussion about either a 5/16” or 3/8” size was required. Had a couple broken and worn, so just replaced them. Wished I have got a couple of spares too at the time.

Best wishes,

Grahame

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Dear Charlie,

That would be great. Have a Clifford Mk IV and a manual which I think has an exploded view of the machine. But the Mk 1a is a very much cruder piece of engineering. Believe the Clifford factory made parts for the MoD in the war and probably rushed to get a roteo on the market soon afterwards. The Jap 5 engine was made in 1948. So do not have a clue if the oil seals in question are the same for both models. In all probability think they would have been improved upon. Be good to know how to take it apart and what the fix is for the leaking problem. Suspect the ID and OD of the original seal may not have a modern equivalent.

Best wishes,

Grahame

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Hi Norman,

You may be able to help me. I bought my Clifford 40 years ago and got a Trusty at the same time. A chap was giving up his ground and wanted to clear his sheds. Used both for a few years, the Trusty had the better engine, but the transmission was knackered. The Clifford was hard to start, but the hooked tines did a really good job in seedbed preparation. It had a massive oil leak where the bevel drive housing joins the rotor axles. Someone told me it was a common fault when the machine gets old because the oil seal was, I think I recall him saying, leather. Which dried out and wore. I used to have to store the machine tilted with the engine on the ground, otherwise it would loose all the oil. Still had to give it a good top it up every time I used it. I put some new tines, big end shells and rings on it, all purchased from Chester Hudson. Then moved and put it away in a shed, ready for the day I had the time to carry out all the repairs to make it a reliable machine again. Two years ago my Trusty Jap 5 engine blew the big end. So I took the engine off the Clifford and made one good engine out of the two. Still have another spare engine, so the plan was to fully re-build that one and fit it to the Clifford.

Where you can help me is with advice about the dismantling of the rotor axles and what I should expect to find in the way of oil seals. Then how to get the parts to fix the problem. Like yourself, am in no rush to do this. At the very earliest it will be a couple of years before I get round to doing it. Have another couple of working rotovators I have done up, so there is no pressure to fix the Clifford.

It was a right old beast to use, no throttle, just the governor to regulate the engine speed. When you pulled the dog clutch handle to engage the rotor you had to do the same for the drive with the next movement of your hand. Otherwise it tried to jerk out of your remaining hand on the handle bars. Was younger, fitter, stronger and quicker back then and it still took some effort to use. Remember I could not get it to start one day with single swings, so kept winding it up as fast as I could. It fired, the handle came out, swung around and hit me straight in the mouth. There was blood everywhere. All good fun though.

Best wishes,

Grahame

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Hi,

I have the same machine in its original colour. Have taken the engine off, so some non faded paint is now exposed. Will take a photo so you can colour match if you wish. But this may take a few days, the machine is buried at the back of a shed. Some experts in the club may be able to help with the exact colour from a previous restoration.

Best wishes,

Grahame

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