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Thanks bud. This video is timed well because I've got a saw I believe has ignition issues. This is a big help. May God bless you and keep you.

Will tuck this one away for future reference. Thanks for all the info you provide for us.

Nice video Tom! Lots of great info. I need to watch this again.

Excellent video. That's more about an ignition coil I've heard from anyone. Thanks 😊

Good information well delivered. Thank you Tom. I will be referencing this video again and again. I bought a box of coils at auction dirt cheap. $20 for about 20 coils, mainly Briggs Quantum and Classic types by casual observation. I will be testing them to see which are keepers.

Probably the most informative and well explained i seen.

Awesome video, great explanation on how to test the coil and where to set the meter. Thanks

I think that I have thanked you before, and if so, never mind !! Thanks Bro, I had this video saved ready for when I needed it, and today, I needed it, and now that I have actually done it, I will most likely remember it.... Thanks, again again....

Another great video Tom! I have been testing some Stihl coils and I was getting those weird readings. I’ll be sure to check them again.

Very comprehensive coverage on ignition coil testing - wish I had seen it years ago. I'm thinking I've thrown out many good ones based on faulty testing criteria. Cheers

Excellent explanation, I enjoy your channel. I have replaced several ignition coils this year for customers.

I had my own workshop for 30 years and murphy was a constant companion so more often than not there was more than 1 problem or inconclusive. If I had a buck for every coil I tested that had good values but was crap....in the end I gave up these tests, it is only an indication ie if the coil is crap this will confirm it...or not. The most useful test (and fast) if the motor is running - but has an ignition problem - is to remove the cap from the coil and start the motor while holding (and being very careful) the end of the lead to the plug or earth if you have more than one cyl. The spark should be fat strong and blue and most importantly should easily be able to jump about 6mm. As you are holding the lead you can easily vary the distance and if the spark faulters and or the engine stops as soon as you increase the distance the slightest from the plug you know that either the coil is faulty or there is not enough power (dodgy electronics normaly wont let the engine run at all) - you have to then eliminate the plug first too of course but most often it is the coil. But if the spark and engine is still going strong with sparks an inch long you know the coil is not at fault. The next test is then the magneto coil (or with a battery ignition simply to measure the voltage at the coil - this will be pulsed if the electronics are not in the coil). Also here there is little point in measuring the resistance thru it as what makes these tests so inconclusive is a broken down insulation not bad enough to open or short it but just enough to allow moisture to get in. This then shorts it as soon as voltage builds up - same goes for the ignition coil. So you need a peak voltage meter which can be bought cheap and put in series on your multimeter. This then allows the multimeter to accurately measure the very short voltage spikes put out by the magneto and immediately shows up any problems with power supply as a high enough voltage of about 90 - 200v AC will not build up. You need to confirm those values depending on what bike/other you have as that is just from memory and I am retired now! There are also measuring charts for assessing the electronic parts but they can be hard to get right as they will vary depending on which multimeter you have. Sometimes all you can do to verify those is to employ a process of elimination. The best part of this vid was how he eliminated the TCI part of the coil from the test - well done. Hope this helps someone! All the best from Aotearoa

thank you for this information - I've saved it to my favorites

thanks for a very well prepared and executed tutorial. Not a moment wasted! Not a single umm or errr. I learnt more than ever about this diagnosis. In my case it was a faulty ceramic resistor in the sparkplug boot. Not cracked. Looked a tiny bit discolored. Found after all the hassle of an engine pull-down for coil testing

Great video! Well explained and to the point!

Nice job Tom, thanks for the explanation. 👍

Very helpful! Thank you!

Great video, very informative

Good explanation of HT coil Thanks a lot

I saved this one Tom I want to give this a try ! Not good at the electrical side of small engine repair 🤷

awesome man thank you for sharing.

Great information Tom 👍

Superhelpful! Thanks

Great video.

Thanks for the tip on testing coils ..iv got a lot of machines..week or no spart

Brilliant many thanks

Very good video.

Excellent

Well done Mate!!☻

Good video, good should help people

Finally someone who knows what they are talking about !

Great video cheers

Good, thorough video, as always but I suspect I'll have to watch it multiple times to have a grasp. In the meantime, a quick question. I recently bought an older Echo chainsaw. The seller mentioned something about the coil, so I assumed it would be a spark problem, but starts right up and runs great. The problem is that the kill switch doesn't work. In true backyard mechanic fashion, I replaced the switch which was quite loose. That didn't fix the issue. Could a faulty ignition coil cause the problem I described? Thanks

Can you add and electronic diagram of the coil spark plug the see all the components? Maybe there is a darlington transistor inside of the coil. Who power the darligton transistor base?

If anyone is wondering about the tree behind him it's a wallum bottlebrush... Anyways...

V clear and concise. Sorry to be dim but ref to Kill Switch or Tab I assume you are referring to the 12v feed from the Ignition Switch. Your comment re removing all corrosion off the mounting plate is v useful as I have taken the coil off my Quattro and treated the base plate with KuRust to neutralise the surface rust that was on it. Before all this the car fired now there is nothing coming from the main HT lead to distributor BUT I have a 12v feed from the ignition switch. Could this KuRust treatment be stopping the earth getting back to the car body? Thanks

One thing to note, I tested a coil on my Honda B16A2 engine. The readings were in spec but the engine wouldn't fire. I purchased a new coil after confirming the primary side trigger was switching. The engine fired up straight away after fitting the new coil. Same goes for coil on plugs on my Yamaha R6, was misfiring at 12000rpm on track, the readings were in spec both hot and cold. I bought and fitted new coils, the bike now revved through 12k and onto 15k whilst accelerating.

I'm working on a sv720-3045 kohler. I have no crank over at all. New battery, checked the starter, which tested ok. Checked plugs, they are shot. Tested coils 1 was (P) .698, (S) 17.80, the other was (P) .734 (S) 19.85. So if I understand correctly the secondary winding on both are a bit low, correct?

Thanks

What is the bush/tree/plant behind you? I would like to get one if it would grow in my area. Thank you.

Is this only applicable with older units? I ask because I tested two brand new ones yesterday after watching this video. Secondary coil - 5.5k, primary coil 8.5 megaohms. After scouring the web someone said the circuitry in newer ones prevents an accurate reading of the primary.

Good video Tom. See you at work sometime buddy.

Tom, I have been watching and re-watching your video on resistance values in small engine ignition modules, specically a 2 stroke module. The secondary measurements on my original module =4100 ohms, while the new module = 2600 ohms. The primary values original module = >30 Mohms ( fritzed?), new module = weird values depending on multimeter scale, 29.5Kohm to 201Kohm to 122 Kohm. I can not rationalize the electronic circuitry impact on the primary readings. Nether coil seems to create spark at my older plug and brand new plug. Any advice here?

If a simple coil with no electronics, I have taken a 6-volt dry cell and hooked up a ground to the armature, hooked up a spark plug, and of course, ground it. Then briefly touch the positive connection and watch the spark plug and if it has a spark, it is probably good. Just don't hold the wire on the primary just touch it like a set of points are opening and closing.

Another excellent video! As you know, you can test resistor spark plug resistance too. :-)

7:11 Pleas, Help me out here, ok so if you get inconsistent reading o the primary coil then proceed to a more accurate testing, which is testing the secondary winding: HT lead to armature HT lead to kill tab When you said if the reading between the HT and armature are correct, but the reading between the HT and kill tab are incorrect that means the electronic components inside the coil are bad? Or just interfering and causing higher/different reading thus giving a false sign that the coil is bad? So the most trusty test is between HT lead to amature? Or both reading HT lead to armature and HT lead to kill tab have to be the same to finally say the coil is good?

My 2003 Honda XR400R service manual doesn't use resistance testing anymore. Instead Peak Voltage specs are listed which means you need an adapter for the multimeter.

Well how do I know if the primary winding is bad or its internal electronics then if a high resistance could mean either is the case?

I got a 0.37 resistance reading for the primary and 73 resistance reading on the secondary. This is a 2 stroke engine. Seems like the primary is higher than you suggested. Is it bad?

Ive just replaced a faulty coil on a 21HP B&S twin. The working coil has a secondary of about 6k Ohms, the other faulty coil has a resistance of around 3k Ohms.

I have a briggs and stratton opposed twin 16.5 it ran good cut haft the lawn shut it off and would not start again tested coil says it's bad sence then I've tryed 6 coils on it and everyone of them went bad on the 3 attempt I disconnected all the wires to the motor except the starter cable still nothing have you ever heard of anything like this ?

I have an old Stihl 041 power saw with electronic Sweden ignition. there is also a German electronic ignition on some of them. And I have 3 parts saws I keep robbing electronic ignitions to keep the spark working. But one by one they fail over the years. There is a coil and it is attached to another part that picks up the magnetic signal from the flywheel. But these 2 parts are no longer available from Stihl. But all 3 coils test at around 1752 ohms which seems very high. Maybe you could test coils from an old 041 Stihl saw and show us how,,,,,,,,,,,,,,,I had to update to a 046 saw, but would like to get the 041 working again,,,,,,,,,,,,

Is it possible the performance of a coil would be affected by heating up? Say after 20min of riding the bike?

Nice video - thanks. What is the name of that beautiful red blooming tree behind you, and since it is blooming now, are you from Australia. Mike Ohio USA

Hi. I’m struggling to be confident about which are the right testing points. I know which one the spark plug lead is. I have two cables connected other than the spark plug lead. One is green and one is black. Not sure which is the kill switch lead. Can you help identify the right connection points for testing? I’m testing a coil for a 2022 Honda CRF 250R motocross bike.

the best video out there...coils suck.

Thank you. I’m hoping that may solve my problem. My motocross bike runs perfectly well for 15-20 min then dramatically looses power. Sounds like it’s choking

Thank you!!!

Good video, what is that plant behind you.

Do you know what kind of tree that is behind you? It's gorgeous!

Our push mower starts using recoil pull cord but not electric start. Replaced battery and bought a used starter. Advice?

I am getting .389 on the primary is that close enough to .5 ?

Hello Mate Will the cause the engine to start idle then when you raise the RPM it dies or hesitates then runs Hard to start when hot

I am confused as you said test resistance and not continuity but my multimeter only has a setting for continuity.

Do the flywheel magnets go bad?

Well I got 25.5 ohms primary and 4736 secondary on the coil I replaced. Here's weird for you. If I put the spark plug against the head I wouldn't get a spark. If I put my finger in between the sparkplug and the head I would.

You should also test the leads. resistence in leads ???

Thanks for the info.

Buy a 500volt megger to check insulation breakdown resistance.

WoW

I stick the wires into the mains and if I see a spark I know it was good.

Thanks mate , I,ve got an 85 year old Villiers mk10 that is giving everybody mixed up with it absolute hell , bad compression despite valves being newly lapped in & gapped , ( bore belled out ) , no spark , previously severely butchered in a failed attempt to get an obscure flywheel off etc . I,ll use your method to test the coils , & go from there . Much obliged , & I,ve clicked the buttons .

👍

👍👍

What is that beautiful tree you are sitting under?

You didn't state what a normal reading between the kill terminal and HT terminal should be when checking for electronics.

what kind of tree is that behind you?

What is that tree

You completely disregarded secondary insulation breakdown. The secondary winding can and most times look normal, but at high voltage it breaks down. A multimeter will not show you if this is an issue.

This video is exactly why I prefer text-based information... don't have to weed through all the other garbage

Multimeters arent really accurate in the .5 ohm range. It could be a dead short and you would never know it. It's better just to swap it out and see

This will not test insulation breakdown.

If you're married you can tell your wife to put her finger in the top of the spark plug and give the recoil starter a pull see what happens. You'll know if it has a good spark.. There's actually a spark tester you can buy very cheap. Sometimes a meter will show a good coil but it will have a voltage leak and arc internally or the spark is weak. Always check the distance between the coil and the flywheel. The correct distance should be the thickness of a business card. It's important to set the distance after removing a coil. While it's good to use a feeler gauge, a business card will work just fine.

You sure don't sound aussie

If you use multimeter 90% of the coils will check Ok

Looks like you only show how to test 2 stroke coil....

He talks to fast.

more ,talk ,less ,Action,

210224 Thank you mate

I was thinking that all you need is a 9 volt battery, a couple of clip leads, and a volunteer to hold on to the secondary connection and the appropriate common connection while you connect and disconnect the 9 volt battery to the primary winding. Simple.

Thanks