How Points and Condensers Work Small Engines 

As a guy who likes taking care of his own equipment these type of tips are invaluable, thanks for spending the time to teach.

Best explanation for condensers, coils and points on small engines. I've had to replace condensers on old lawnmowers and generators over the years.

Great explanation on points, ignition system!!! I have a Wheel Horse that I bough new in 1976 that has points. Years back I pulled the flywheel only to find that the points are conveniently located on the block. Can’t beat experience or having a manual :)

Sending a big hug to you my friend, from Argentina, once again spreading and teaching very useful information! See you!

Thanks for the video. Good stuff and a generally clear explanation. I feel you may have got CDI and points ignition systems somewhat confused. What you may find happens is that the current generated as a double and reversed wave ( as you pointed out) is allowed to flow through the points to ground creating a circuit. This circuit is broken by the points at the peak of the second wave, The condenser does stop arcing but more than just to save the points it precipitates a sharp instantaneous collapse of the magnetic field and it is this which generates the massively high voltage in the secondary coil. Keep up the excellent work I love your tips!

A day that you don't learn something is a day wasted. I have picked up a lot of information and you have jogged my memory every now and then. Thank you!

I've seen points and condenser's but never really knew how they worked, interesting stuff. Very informative video.

sorry you need to read up on the magneto ignition system, the points dont stay open most of tbe time and the condenser does not feed current back through the primary coil

Thanks for the video. I've got a little 2 hp Briggs 60102 and after it started running lean and dying on me, I decided to replace all of the gaskets (intake, gas tank, crankcase, valve cover, and even the head gasket). I had adjusted to carb with no luck, so I figured I'd just do a little overhaul since the gaskets were cheap enough. I checked the points and condenser and all seemed really clean plus no cracks on the top of the condenser. I sanded the points and set the gap to 20 thousandths, although they were pretty clean to begin with and the gap was at 22 thousandths before. I fired it back up and it will run quite well at half throttle and idle pretty good, but will sputter and want to quit at full throttle. Tried adjusting the carb both directions with no luck. I would assume my points and condenser are fine if it runs so consistently at half throttle, but thought I'd run it by you to see what you think. I just regapped the spark plug, but figure I could replace that just to eliminate it as a cause.

Really appreciate this information. I have a Tecumseh H50 that I'm trying to get running and couldn't wrap my head around how the ignition worked. Thank you!

Amazing video! Lawn mowers, generators... a lot of different applications 👍🏽

Good tutorial and a very simple explanation. Even I could understand it. Thank you.

Great simple overview and explanation. I can and have done mechanical repairs but the electronic parts have always been a bit of mystery to me..........Thanks again.

I already knew all of this but I guess your so captivating I had to keep watching LOL This is Awesome for a new beginner in small engine repair.

Good explanation of how points work..... do you have a vid on a lawn boy D series engine points setup. Thanks

Now I'm really confused I thought the points were closed most of the time and they opened momentarily for the power to travel to the plug instead of ground.

Awesome...thanks for the info. Hope your having a good winter in Salt Lake. Its been a banner year for plowing and pond hockey here in Cleveland.

Great video, very useful, thankyou.

one month or more in school where i can leaned this things in less than 7 minutes...thanks man!

A fountain of knowledge - thanks!!

That is the info I needed. Thank you!

oh thank you so much i have my test and i needed an explanation about Condensor

I like the good clear explanation and demonstration

Just a quick question the new points I installed for my Kohler K321. If I can see a bright spark when the motor is turning over would this indicate a bad condenser? Thanks for posting the video.

Good video gets right to the point.

i'vу been looking for this video for sooooooo long. thank you kindly

Very interesting, never know that. Neat and clear explanation.

Great Demo !!!

Do you really have a 'dent' in your crankshaft ? Normally there's a 'bulge', because the secondary circuit gets activated when the points open, not close as you say! Or is this only with battery equipped systems? Does this system work the other way around than normal? please clarify, some1...

Thanks for the video, good info.

I have a Wisconsin Engine on a Essick Plaster mixer, I was told once a magneto gets wet it ruins it. I wish you could show the points or magneto. Q. Is the transformer & Magneto the same?

A secondary tap of the coil provides a signal to do many things prior to hi voltage rectification for the spark plug. Many people are looking for passive analog devices to support electrical needs sans onboard battery.

Like the simple explanation

Hey man, I have been wondering for a while now how to sort the mystery of this system as I bought a 1978 Honda CB550k. This really clarified it, and I'm sure I'll watch it a few times. Thanks!!

What about magnetos for twin cylinder engines? I believe the secondary coil is not grounded by a coil tap and only grounds by arcing across both spark plugs.

Nice, simple explanation.

Thank you and Well done........I have a Puch moped........the ignition system incorporates a "kill switch" fitted to the handlebars...........wil this basically be a open circuit or a grounded circuit, to/from the coil ? Thanks

another great info vid bro, cheers

Very informative thanks . I have a 1978 Bultaco Sherpa 250. Can't seem to get it to run right, it'll run at full pelt or not at all. Think I might have wired the primery ciol up wrong or may have a short some where. are the Primery and the condeser bolted to the engine ( to ground ) or are they insulated in some ay

Come On Let's help this guy get to a thousand subscriptions!

Nice info :) you do a great course in misc great stuff to know if you like to fix and work on stuff. ... you can use that if you wanna lol. I've got a Walmart Mower that's been great, but it's totally different than anything I ever saw, baffling a bit, but I better figure it out cause grass will be coming soon.

Even on youtube will see video's by mechanics, auto electricians and others who have absolutely no idea that the condenser (capacitor) boosts the secondary voltage. Good video.

This is some pretty fascinating information

Hi, good explanation. You need to follow up on how the engine revs are governed as well as the theory behind the engine revving up and down. Thanks

65!! I love your banner!! Excellent explanation of how the entire ignition system works on a magneto engine!! Where did you get your banner made? Cheers!! Zip~

really great video! thanks A lot.!

Great vid... Would love to see if you come across points failing in leaf blowers. I've had two blowers go bad (no spark) in 2 years. The latest was a Poulan. Noticing on youtube a lot of the poulan leaf blowers are failing for different reasons.

Smashing video :-)) Hmm i allways thought the capacitor and primary were like a tuned circuit and produced a stable magnetic field, then when the points closed the sudden loss made the primary over react (as charged inductors dont like change) and create a spike of intense magnitism trying to counteract the loss and firing the secondary. Looks like i may have been wrong :-(( Inductors do react to losses though, they do have some very odd propertys lol.

very nicely explained

Do you know about villiers C45 industrial 4 stroke engines and magnetos timings.

Great video as always SixtyFive!

Thanks for the information.

I have a TecumsehH540 or HS40 and the points are closed all the time until a lobe on the crank open them up for a few degrees of rotation, seems backwards from what you say being open 90% of the time, either way, no spark and while points are open no resistance from the open point to ground, I haven't worked with points for 30 years so I forgot alot. Any ideas on how to test? Nice Vid!

It is possible to remove the magnetron and put on the ignition system of a motorcycle.

Thanks for the excellent video! ...two questions: 1) Is the spark plug mounted above the EXACT center of the piston on top of a combustion chamber. 2) Also, at TDC, how far from the piston is the bottom of the plug? This information will be of GREAT help! Thanks much,

Thanks for explaining this.

This seems to show the spark plug fires every stroke but it seems a four stroke should fire every other stroke. I suppose it could fire right at tdc of the intake stroke also and it wouldn't affect anything?

Excellent explanation - I’m confused at how grounding the primary circuit stops production magnetism since the fly wheel is still spinning wouldn’t the voltage still be induced into the primary? Current would flow from the grounded primary to the other side of the primary completing a circuit. I know clearly I’m wrong I just don’t understand. I want to add, I don’t think the magnets on the fly wheel need to have both positive and negative polarities, if we look at a coil pack on modern engines they use the 12VDC from the battery to operate. All we need is a magnetic spinning on the flywheel to cut flux into the primary coil. Grounding the secondary makes perfect sense to shunt the spark back to the coil but also raises another question - when doing so wouldn’t the current from shorting to ground be high due to the voltage being extremely high? I would think the secondary’s coil would short out.

Thanks. Very helpful.

so when that gap is closed and points are touching eachothers then it will give spark?

I have a small engine with this, and I get power to the top of the plug, but no spark. I put the plug in another engine and it has spark. I cleaned the points and the coil seems to be working (idk how he tested it). What would anybody suggest?

Thanks!!

Thanks for this :) been working on making a Honda CG125 run off it's own steam with no lights or main loom or anything as a fun little flat tracker project and whilst I kinda knew what to do, I've never had a points bike before so this confirmed everything for me :)

Well done! Thanks Dude!

Great video

Thanks for helping me understand watt going on. I do like to know watt happens. It's all good stuff.

I had a ST350 Ariens snow blower with no spark so I change the Ignition coil- condenser and the point but still no spark can you help me thank you

Very good video!!

Thank you

good solid info ---thanks

Great explanation! Thanks! In order to obtain a very HIGH VOLTAGE in the secondary, we need a GREAT FLUX CHANGE through the core (implicitly secondary coil), because the greater the flux change the greater the voltage obtained. Therefore, besides collapsing the flux in the primary, we ALSO REVERSE the current direction through it, obtaining a GREATER FLUX DECAY through the primary, and this is exactly what the capacitor does. A capacitor always opposes a build up in voltage by charging itself. The contactor circuit here shortens both the primary coil and the capacitor. The capacitor opposes the build up of the induced voltage in the primary by charging up, and immediately after the circuit opens (10 degrees after Neutral, EGAP), the capacitor is no longer shortened by the contactor, so it discharges solely through the primary coil. Keep in mind, that any collapsing magnetic field through a coil, give rise to a self induced current through that coil. In our case, the self induced current due to the collapsing magnetic field is opposed by the capacitor current through the primary, thus hurrying up the collapse (according to the Right-Hand Corkscrew Rule) ! In other words, the capacitor only forces a reversed current through the primary, to oppose the selfinduced one, in the end accelerating the collapse of the induced magnetic field. This happens very quickly, right after 10 degrees past Neutral (EGAP). At this point, the CHANGE of the rotor magnetic field in the core is just below peak value, which means the EMFs generated in both the primary and secondary coils are just below maximum. Also, the CHANGES in the rotor magnetic field and the collapsing primary field have the same directions (very important)! As the two magnetic fields have the same direction of change, they will superimpose, thus give rise to a LARGE FLUX CHANGE through the core, implicitly through the secondary coil. This is like a spike in the magnetic flux change through it, leading to a very high EMF at the ends of the secondary, which translates in a spark obtained at the sparkplug. Moreover the capacitor and primary coil form a tuned LC circuit. All this starts when the EGAP commences and up to the point when N reaches the yoke (Full Register position), the superimposed flux change being large enough to create the spark. ru-vid.com/video/%D0%B2%D0%B8%D0%B4%D0%B5%D0%BE-OMLSNwQiiKg.html

Hey, great video. I'm struggling with an old Briggs 2hp... I'm getting power to the plug but not enough to make it jump. Any ideas?

do you know approximate resistance of the coil of an 8hp Tecumseh thats in a snapper rear eng mower?

Love this

Sehr Gut!!! great teaching video -- I could Not have done any better!!!

This information is excellent.

Too wonderful in your detailing. But I am still having difficulty of no spark in a very old Kohler engine Cleaned the points but still no spark not sure of condenser but as you say they rarely go. I must still have a bad condenser.

Hello, I was very pleased with your explanation on how dynamo ignition works, didn't have a clue until viewing your videao. Maybe a stupid question but I'm wondering, how high should the secondary voltage (feeding the spark plug) be? Would that be like hundreds- or thousands of volts? Up until now, haven't risked to test it.... maybe for the best..... Kind regards, Jacques Belgium. So as you can see you've got viewers all over the world although Belgium is a small European Country.

What should be the distance between the fly wheel and the transformer? Should it be a couple a thousand or touching it? Thank you. Good explanation.

Great vid

Time to go back to school. The points stay CLOSED most of the time. When the points OPEN momentarily, The field collapses at that point, and the magic happens. Careful what you tell folks.

"magnetical" love it

Thanks for sharing this video! So if I'm seeing a bright spark at the points when my Koler K321 is turning over should I assume the condenser is bad?

i fitted a stihl points type ignition plate in an old echo saw... got NO SPARK until turning in wrong direction and then big blue spark.....checked position of strongest magnet and cut a keyway to get magnet leaving 2nd armature end as points open.... now sparks but weaker. strange as the stihl was anticlockwise rotation and echo is anticlockwise rotation....

Thanks

My spark advance module plugs to the second prong

I have to ask I have a vintage dirt bike and I just replaced the points and condenser and it's still sparking at the points when not running so do you know what the issue is? Thanks

Great video! How do you figure out if a condenser is still any good?

Thanks for another informative video.

I just bought a used Toro groundmaster 52(1979) it was running well and cut beautifully. It died while I had been cutting for about 1.5. It will turn over, but no spark. Have changed the armature, did as instructed on your video re condenser and point, checked to see if any wires in harness broken extra, but still no consistant spark, only once in a blue moon. Any ideas. Seat kill switch as been bypassed.. thxs

well explained mate.

Don’t need North and south poles on flywheel only one polarity. When the magnet passes the magnetic field collapses and induces a voltage to secondary weather AC or DC it’s the same. Grounding the primary should not cause the spark to open, if so please explain the path for current.

If I ever met you I would buy you a beer. That is, of course, if you like beer... Ah, who am I kidding - everyone likes beer!

If the contacts close every rotation of the crank, does that mean the spark fires on both the Intake and Combustion cycle?

Your explanation is incorrect. Wikipedia better explains: In the type known as a shuttle magneto, the engine rotates a coil of wire between the poles of a magnet. In the inductor magneto, the magnet is rotated and the coil remains stationary. As the magnet moves with respect to the coil, the magnetic flux linkage of the coil changes. This induces an EMF in the coil, which in turn causes a current to flow. One or more times per revolution, just as the magnet pole moves away from the coil and the magnetic flux begins to decrease, a cam opens the contact breaker and interrupts the current. This causes the electromagnetic field in the primary coil to collapse rapidly. As the field collapses rapidly there is a large voltage induced (as described by Faraday's Law) across the primary coil. As the points begin to open, point spacing is initially such that the voltage across the primary coil would arc across the points. A capacitor is placed across the points which absorbs the energy stored in the leakage inductance of the primary coil, and slows the rise time of the primary winding voltage to allow the points to open fully.[5] The capacitor's function is similar to that of a snubber as found in a flyback converter. A second coil, with many more turns than the primary, is wound on the same iron core to form an electrical transformer. The ratio of turns in the secondary winding to the number of turns in the primary winding, is called the turns ratio. Voltage across the primary coil results in a proportional voltage being induced across the secondary winding of the coil. 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. As the voltage of the primary winding rises to several hundred volts,[5][6] 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.[5] The capacitor and the coil together form a resonant circuit which allows the energy to oscillate from the capacitor to the coil and back again. Due to the inevitable losses in the system, this oscillation decays fairly rapidly. 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. On more advanced magnetos the cam ring can be rotated by an external linkage to alter the ignition timing. In a modern installation, the magneto only has a single low tension winding which is connected to an external ignition coil which not only has a low tension winding, but also a secondary winding of many thousands of turns to deliver the high voltage required for the spark plug(s). Such a system is known as an "energy transfer" ignition system. 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 insulate-at the expense of efficiency). In more modern times, insulation materials have improved to the point where constructing self-contained magnetos is relatively easy, but energy transfer systems are still used where the ultimate in reliability is required such as in aviation engines. Edit

Hi great video. Wondering if anyone can help me. Kohler 8hp K181 . Replaced coil, still no spark. I am thinking I probably should have ordered a condenser also. By the way only way for me to find parts is EBay, straight from China of course so just hoping they are good. Anyway in Checking the condenser, I am on 20k ohm setting, Red probe to wire, black too body, meter just stays at 1, should I not see a certain ohm reading, meaning I am charging the condenser? Also I would then check dc volts I believe, what am I looking for MV of something , then voltage should drop? Thanks for any help.

Very complicated. How did anyone think of points and condensers?

Thanks for the video, I cant wait to get home and show my husband how to trouble shoot this!

what r symptoms of weak spark I have a old Neptune Outboard it don't wanna jump the spark across the spark pulg but when I hold the spark plug wire with my hand to ground I get a shock

Hello sixtyfiveford@@@ I was wondering if you can help me with my problem I have a ruggerini small engine that it's working but the condenser it's about to run out due to the wire it's coming a parts from it, I was wondering if all the condensers works the same because I just can't find the condenser for this engine please help