The other thing I have noticed is the spark will arc to ground when compression is on the plug if external arcingis the path of least resistance. 0000003086 00000 n replacement for the condenser (capacitor) in (Chinese) At any one time, we reckon to Rotate the armature until the contact-breaker points are open. detailed instructions in our 'condensectomy' ring. I have seen that a lot on FM mags. [7] Ignition magnetos were largely replaced by ignition coils once batteries became common in cars, since a battery-operated coil can provide a high-voltage spark even at low speeds, making starting easier.[8]. anglais, votre convenance. rectifiers (and wiring diagrams) of use to all Put a smear of grease on the lobe(s) of the cam. I can guarantee every British motorcycle powered by a magneto i either not delivering maximum spark and/or is on the verge of failing if the original Lucas capacitor has not been replaced. Put a smear of grease on the surface of the cam that engages its housing. This will not stop the coil from working. and other magneto parts. The ratio of turns in the secondary winding to the number of turns in the primary winding, is called the turns ratio. If I was working on it, first I would want a 5/16" air gap consistent spark minimum from the coil terminal to ground. However, provided the reading is more than about 500 ohms, it is probably OK. -- Tickover, pulling away, and low-speed running erratic. I highly doubt it is excessive unless someone has been grinding the rotor or the cap. 0000006861 00000 n Always good to learn how to check lucas parts, one of the weaker parts of a triumph motor.. Classic Cycles inc. 2199 N. Batavia Suite J. We are unfortunately not able to offer We will check all the parts of the magneto for faults and will provide a firm quotation for a repair along with a description of the magneto repair required. It's a 6v system, so the starter turns rather slowly (maybe 80rpm), but I think it should be fast enoughto start. detailed guide to maintaining and Thank you for your patience. 0000001320 00000 n Dansk The impulse coupling uses a spring, a hub cam with flyweights, and a shell. if it doesn't jump 3/16" double check the points to see if they are shiny clean the whole face of each point. The reading should be between 0.5 and 0.7 ohms greater than your first reading. errors in the translations. For a better experience, please enable JavaScript in your browser before proceeding. If your magneto is loosing spark after a short amount of time running, or is hard to start it is most likely a condenser failure. If the timing is not correct on both lobes, the reason could be that: the contact-breaker assembly is wobbly on the end of the armature; the cam or its housing were incorrectly machined (rare); with ring-cam magnetos, the armature and cam are not coaxial due to the outer race of the bearing at the contact-breaker end not being seated properly by its insulator in the cam housing. grade to avoid carbon deposits on the slip 0000005468 00000 n Italiana With a twin, repeat with the other pick-up. The magneto is rebuilt by a reputable US shop. Our Svensk Checked it over and found no spark. magnetos available for sale or in 85 0 obj<>stream If it is significantly higher, there is a bad connection or break in the low-tension circuit, in which case the magneto will need a more complete overhaul. 0000004414 00000 n Measure the resistance between the magneto body and terminal in the plug cap. rebuilt amature runs about 85pnds from independent ignition. Make sure they are there and can move in their holders and give them a good clean. Links to other service providers can be found JVC 4VR-5436X 4 Channel Stereo Receiver Service Manual Original. She was factory fitted with a Morris Vedette MKII engine which has a lucas rf4 magneto. DO NOT ATTEMPT THIS IF YOU ARE FITTED WITH A PACEMAKER, OR HAVE A HEART CONDITION, OR IF YOU REALLY HATE ELECTRIC SHOCKS. 2. Mechanical - Bearings, insulation, washers and shimming the armature. Check the condition of the HT lead(s) and plug-cap(s) and replace where necessary. 096792012013 - 2020 | Website design by The Net Effect of Sheffield, Website design by The Net Effect of Sheffield. If you have an auto-ranging meter, the reading might jump about a bit on the way while it changes scales. themselves. An ignition magneto (also called a high-tension magneto) is an older type of ignition system used in spark-ignition engines (such as petrol engines). I tested the HT wire and spark plug and both are fine. This was examined earlier. With the plugs in the engine connect one plug outside like you have been testing it to confirm no spark, If there is spark present I would open the gap of an old spark plug to 3/16" and see if the spark will jump that gap. However, if the outside of the pick-up is also oily, perhaps its all caused by an engine oil leak. The condensers we get now are made in area's that there are no or very poor quality control checks. I purchased this Lister D petrol (gasoline) engine that came on a trolley with an Aerograph air compressor. Can you rig up real cables? [2] An ignition magneto also includes an electrical transformer,[2] which converts the electricity to a higher voltage (with the trade-off being a corresponding reduction in the output current).[2]. magnetos. If higher than that, investigate. Others have an earth brush between the main body of the magneto and an earth track of the armature. I was bench testing by tuning the mag slowly by hand, without the impulse coupling attached, so 1/4" is a good distance. If it was a typo then you can run it with the cap and rotor off by just holding your wire to the HT terminal and that would eliminate the cap land rotor from the equation. Blue spark is great but if it can only jump .03" when external of a cylinder with no compression pressureswhen you add the compression and fuel mix it will fall on its face. Not quite as large as ideal, but simple. Having set the timing with the points opening on one cam lobe, you should check that it is also correct with the points opening on the other cam lobe. Another problem, due to constant hot, cold, expansion, contraction, vibration or mechanical impact, is breakage of the fine winding wire. The family of Bijan Ghaisar, shot dead by two U.S. Park Police officers as he slowly drove his Jeep Grand Cherokee away from them in 2017, agreed to settle their lawsuit against the . I also needed a new coil for it which I installed, cleaned the mag up and replaced any bits it needed. Check that all the insulators are in good shape, and reassemble the contact breaker assembly. load correctly in the translated versions of the pages. Place a clean piece of strong paper between the points, and with the points closed pull the paper out. With the engine running, place your hand over the pick-up with the same hand also touching the magneto body. With Lucas devices, the fixing hole at one end of the contact-breaker spring is slotted so that the effective length of the spring can be adjusted as necessary. Turn the armature in its proper direction of rotation until the contact-breaker points are just starting to open on one of the cam lobes. The place to buy our EasyCap condensers And a f-ing video! Learn how and when to remove this template message, https://en.wikipedia.org/w/index.php?title=Ignition_magneto&oldid=1150712364, Short description is different from Wikidata, Articles with unsourced statements from January 2023, Articles needing additional references from January 2023, All articles needing additional references, Creative Commons Attribution-ShareAlike License 3.0, This page was last edited on 19 April 2023, at 18:38. capacitance to satisfactory ignition system With your multimeter set to display resistance and connected to the opposite faces of the circuit board of the EasyCap (and with your fingers touching no more than one side of the circuit), the meter reading should climb up from a low value until it goes off the scale (OL). Due to the inevitable losses in the system, this oscillation decays fairly rapidly. You are probably loosing amperage through the jumper cables. This disables the magneto to reduce the risk of electric shock and fire. After you get your spark strong enough, then worry about cap and rotor. Values vary considerably depending on the make and model of magneto and who wound it. What else could possibly be grounding this? When the magneto is supposed to fire, the flyweights are released by the action of the body contacting the trigger ramp. If you do not obtain readings substantially the same as the reading you obtained in the internal HT continuity section, and if everything else you previously checked is still good, it indicates that the pick-up brush(es) is/are not making good electrical contact with the brass of the slip ring. Some have both types of earth brush. The turns ratio between the primary and secondary coil is selected so that the voltage across the secondary reaches a very high value, enough to arc across the gap of the spark plug. MochetVelo PA. If it does not jump 3/16" it probably will not fire a cylinder under compression. slip rings and pick-ups for Lucas and BTH I'm working on a Lucas Mag right now for the first time and this is extremely helpful. We always replace the capacitor during a repair as experience has show us that the capacitor tends to be the most unreliable part. Also, with the points open, check that there is an open circuit between them; if fitted with a Brightspark EasyCap, it will take a little while for the resistance reading to climb off the scale. and just how were you able to find one of those bastards that still worked?!?!?! Any high tension magneto will have way more than 7 ohms resistance on the secondary circuit. In the Lucas MO1, it is on one side, adjacent the contact-breaker housing. Grease. Thank you for your patience. Check the state of the contact return spring and replace if broken. old-style capacitor (the 'condensectomy') and The magneto gives a good spark when spun by hand or when kicked over with the plugs removed. If there is a lubricating felt, soak it in oil. i have had 3 done here by ed strain that included rebuild with remagnatized body for a little more than $200.00. Excellent "how-to". Fantastic! He got it and thought the ring the points rides in came out and just needed pushed in. In either case, the magneto needs a more complete overhaul. downloadable drawings for those of you who Fit the magneto gear to the magneto shaft and finger tighten the nut ONLY until the gear is snug on the tapered shaft. 0000007301 00000 n Franaise It shouldnt be very many ohms, and certainly less than 30 ohms. detailed support we offer. When inserting the brushes; you may have to do. 82 23 The voltage generated across magneto coils is quite high, in the order of 20,000 volt if no spark plugs are in place. Without suppressor: suppressor: Percentage difference with suppressor: Peak HT voltage to initiate spark: 9600 V: 10600 V at magneto: 10.4 %: 9300 V at spark gap-3.1 %: DC component of HT current immediately after striking spark: 53 mA: 52 mA-1.8 % making your own bearing and slip-ring pullers; The coils are, of course, designed for this pressure but no insulation is perfect. Regrettably, some Acrobat .pdf files might in the translations. equipment. The last of these possible reasons is very often the cause. wish to make the required puller tool performance. From time to time we have complete Built into the case of the magneto are magnets, permanent magnets. Armoto LtdRegistered & Trading Address:Unit 26, M1 Commerce Park, Markham Lane, Duckmanton, Chesterfield S44 5HSTelephone: 01246 826667 | [email protected] in England Company No. Lucas Ga4 Magneto Austin 7, Morris, Riley And Many Others Service Exchan. Joined: Oct 2009. information as we can about the electrical equipment First test is to take the plug caps off the HT leads and position the ends of the HT leads 1/4" away from the casting. Really need a coil tester. Great photos, quality! Just to reinforce a point here of something very well done that you did in the how-to: when you're testing a mag like this, ALWAYS have the plug wires hooked up with a gap (or plugs) to ground so that energy has somewhere to go. As the voltage of the primary winding rises to several hundred volts,[3][4] the voltage on the secondary winding rises to several tens of thousands of volts, since the secondary winding typically has 100 times as many turns as the primary winding.[3]. If not provided with a safety gap, there is a risk of expensive damage. many ignition systems, focusing especially on Gift Article. If you can't get even 1/4", I would be worried it would not work under the stress of being in the combustion chamber. 0000001015 00000 n Thanks. If everything were perfect and clean, the resistance should be infinite (OL). and overhauls. VerticalScope Inc., 111 Peter Street, Suite 600, Toronto, Ontario, M5V 2H1, Canada. Capacitors, which are short-term storage devices, often fail in older magnetos due to dielectric degradation (short circuit) or conductor breakage (open circuit). Check out our magneto armature winding service. All rewound units now have modern condensers and enameled wire. Once the insulation has been broken down once, it often makes it easier for it to be broken down again. You can check for this by trying to start in a dark area with no lighting. With other models, it may be inaccessible while the magneto is in situ, for example underneath. I worked on farm equipment for my last real service job from 2013 thru 2016. Nearly all magnetos have a gasket between the pick-up and the magneto body (a) to prevent water entry and (b) to set the correct clearance between the pick-up holder and the slip ring. After a series of checks, I sent it back to the rebuilder. Brightspark Magnetos is now able to offer a remagnetising service, using our specially-developed remagnetising and measuring equipment to help you restore your magneto to tip-top condition. Check the cam surface. Carefully check for any cracks or pin-holes in the pick-up. Photo-sequences of stripping and We would therefore strongly advise against ever trying to make a magneto strike a spark across a gap of anything in excess of 7.5 mm in fresh air. Magneto coils are usually a long time dying. If there are any, repeat until the paper comes out clean. With the earth brush(es) now replaced, measure the resistance between the back-plate of the contact breaker assembly and the main body of the magneto. Take a look part-exchange. On the very first BSA I ever owned, I sufferred the same problem. With some magnetos, the main-body earth brush is accessible with the magneto in situ. Under construction, so far showing video Dansk Then wash the points with petrol and dry them. With an open circuit the device has no CAPACITY to absorb the reaction voltage (back EMF) from the coil, therefore this energy is dissipated across the timing contact which quickly burns away. This video details the work done to the magneto so far. use in our workshop for magneto servicing yourselves. Make a note of the reading; youll need to refer to it later. Thoroughly clean the pick-up using a rag moistened with petrol. At least I assume so: My timing light (seen in photo clamped to plug wire #1) illuminates correctly when plug #1 is unscrewed from the engine and sparks, but it does not light up when the plug is screwed into the engine. If an earth brush is fitted behind the back-plate, check that the spring is good, that the brush is free to move and that it is not unduly worn in length or diameter. Then measure the resistance between the two points of the contact-breaker. With the contact-breaker assembly still removed from the magneto, and with a multimeter set to measure resistance, check that with the points closed there is a short circuit between them (as close to 0 as your multimeter goes). This dissipates the energy that was stored in the condenser in time for the next closure of the points, leaving the condenser discharged and ready to repeat the cycle. Rotate the armature and check that the contact- breaker spring never touches the cam. 2,330 views Oct 18, 2020 16 Dislike Share Air Fuel Mixologist 1.31K subscribers I purchased this Lister D petrol (gasoline). Coil may still function somewhat and not completely failed but ratio of turns lost because of insulation breakdown. It is also used in modern piston-engined aircraft[citation needed] (even though a battery is present), to avoid the engine relying on an electrical system. If your bike runs poorly, backfires at all but idle, stalls out and won't start back when hot, then works again when cool. 0 Initially this was done because it was easier to provide good insulation for the secondary winding of an external coil than it was in a coil buried in the construction of the magneto (early magnetos had the coil assembly externally to the rotating parts to make them easier to insulateat the expense of efficiency). Having removed the contact-breaker assembly from the magneto, disassemble it, noting where each part was. %%EOF Some original units are still in service today. Great post! When we undertake the renovation of these magnetos, we examine the following:-. With twin- or multi-cylinder magnetos, and some single-cylinder magnetos, the brass is a segment, rather than a complete ring, and you may need to rotate the armature in order to be able to see it. I do not know it all but I will try to help. Replace the main-body earth brush, if applicable. The plugs are non resistor, gaped at -025", and are new. Rotate the armature and check that, when the points are fully open, the moving point assembly is not fouling anything. To maintain a dedicated website that covers the Could be bad parts if spark just gets a lot weaker but if spark totally goes away when cap and rotor are installed, be sure the when you install them it does not short out the primary, give the rotor a closer ground to jump to or hold the points open, etc.
lucas magneto not sparking
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