Fixing Ignition Problems in Four Cylinder Motorcycles

[@matthewpaget9742]

Great video! Finally broke it down in a simple way to understand

[@whitedoggarage]

Glad it could help and thanks for watching.

[@paweltarnowski383]

Excellent video, thank you.

[@whitedoggarage]

Thank you for watching 👍👍👍

[@andrewmartin7938]

One of the best ignition explanations and troubleshooting videos I have ever seen. Great work Bob. Please keep them coming, especially on the UJM 4’s!

[@whitedoggarage]

Thankyou very much for your kind comments. Old UJM 4's are my favourites.

[@JoeRocket-sf6qs]

Very underrated video,lot of good understandable info,thanks for making it

[@whitedoggarage]

Thank you for your kind comments. 👍👍👍

[@ambersmith6517]

very well done

[@whitedoggarage]

Thankyou.

[@djderb]

Great simple video thanks,ive the same model here in NZ

[@whitedoggarage]

Thanks for your comment. That one has about 350,000 km on it and at 42 years old provides a few things to fix. It is well overdue a complete restoration, but I am not finding the time at the moment to do it. Thanks again and good luck with yours.

[@philiponsolent7232]

Thanks for a comprehensive video. My bike has been sitting for 6 months and wouldn't start. Now one cylinder is down, (it's pair is firing ok)so it probably isn't the coil, but really useful information for the future.

[@whitedoggarage]

Glad you enjoyed the video. Sitting for six month and one cylinder down, start with the obvious, is there spark? If there is spark then after sitting for six months it is probably some gunge from evaporated fuel in the carby. Here in Oz, back after one of my trips and I had a six month one last year, I first drain all the carburettor bowls so the fuel is a bit fresher. Then I try and use the fuel that was in the tank as soon as possible and get new stuff. Petrol does not last like it used to here. Good luck with your fettling 👍👍👍.

[@philiponsolent7232]

Thanks for taking the time to reply. The plug is wet and smells of fuel, so further investigation is needed. Pretty cold here for fettling in the garage, just have to try repairing my clock that went twang last night until better weather.

[@whitedoggarage]

@@philiponsolent7232 I suppose it is all relative, I sort of imagine the Solent, being down the bottom is a warmer area of Britain, but it is winter there at the moment. Here in Brisbane, Queensland we are enjoying 30 to 36 degree Celcius days with about 70% humidity, and a bit of cool would not do any harm - but it is summer and this is what it is like. Good luck with the clock and it wont hurt the bike to wait until it is a bit warmer.

[@philiponsolent7232]

@@whitedoggarage I thought I had solved it, having stripped the carbs and cleaned them. All appeared well until today when I took the bike for its annual test, I didn't get much further than the end of the road with a misfire on 1 but further investigation showed no 4 was also misfiring. I was a little confused because I am getting a spark at 1 and 4 but having watched again this might be a problem as the motor warms up. Your videos have been really useful, its like having a super manual, appreciate you take the time to pass on your knowledge.

[@whitedoggarage]

@@philiponsolent7232 I would check the primary and secondary winding resistances on the coil, hot and cold, you are looking for not much, ~ 3 ohms, and a bit, ~ 6000 ohms resistance from memory. I would be tempted to trim a half an inch off the end of the coil leads, but if they are misfiring when warmed up I would be looking for a crack in the coils. You could try, with the tank off, starting it up in the dark and looking for spark jumping from the coil or a lead to metal. If the leak is from a lead, I would replace the lead. If the leak is from the coil, araldite or a similar epoxy will probably fix it. Good luck.

[@markwhalen5300]

I enjoyed the different explanations of the ignition systems, it has been a while for me so I learned alot!

[@whitedoggarage]

Those explanations of the different systems were unscripted, so I keep thinking I may have missed something. I looked at a six cylinder Honda the other day and realized that it had a capacitor discharge system so maybe I should have covered those in more detail.

[@markwhalen5300]

@@whitedoggarage i think it was a great overview, technically you could dedicate an hour to understanding each one.

[@whitedoggarage]

@@markwhalen5300 Yep thanks, I was horrified at how long the video ended up at. My average viewer has an attention span of less than 10 minutes and this one runs for just under 30. I wanted to give viewers pointers as to where to look and you are right I could have spent an hour on each one.

[@rickconstant6106]

Maybe it doesn't apply to this model, but isn't the signal wire to the coil usually on the negative side, with the positive being a continuous supply?

[@whitedoggarage]

Rick, you are probably right. I am away on holiday at the moment and can't check my system. But I see this is the case for the more simpler ignition system of the the earlier 8 valve models, so I would imagine the same holds for the 16 valve system. Good point and thanks for raising it.

[@TakamiWoodshop]

Bob that was a great level of detail - over my head I'm afraid but nevertheless I wish you a great 2021 mate!

[@whitedoggarage]

Thanks Rob, wishing you a great 2021 too mate.

[@gabrielramireznahim1904]

Buen video. Gracias. Saludos

[@whitedoggarage]

Gracias 👍👍👍

[@wildracoon666]

Great advice Thankyou

[@whitedoggarage]

Thankyou, I hope you found it useful.

[@markwhalen5300]

15:55 in Colorado, because of the dry climate, the life expectancy of a Cap on a shelf is about 10-15 years, a working Cap 2-10 years. I never reuse, and always buy fresh, unless circumstances dont allow it. yes.. some caps can last 50 years, but if a Cap is in the circuit, as it is here, I recommend replacing it when maintenance (point replacement) is preformed, what are your thoughts?

[@whitedoggarage]

Well I have never replaced a capacitor unless I thought it was the source or part of the problem. But replacing it when the points are replaced is probably a good idea.

[@torbjorntroell5985]

Hi Bob, just took out my -82 1100 Katana and see display not showing any RPM. And also i feel engine have problem with ignition. Do you think it´s the signal generator (if RPM is from signal generator) Thanks in advance //Torbjörn "Sweden"

[@whitedoggarage]

Good question Torbjörn. By signal generator, do you mean the pick up unit or the transistor unit it signals to. They are both related in signal generation and thus the tachometer, but usually the fault lies with the transistor unit. The rpm reading is based on the signal pulses to one of the coils (the one with the orange or orange/white wire - I am on holiday at the moment and away from the garage so can't check the detail). That should also cause a problem with the ignition. Usually the transistor unit fails outright and you loose spark on all plugs. If your motor runs, then I would start by checking the wiring between the signal generator and the transistor unit and from the transistor unit to the coil. If you have a rough running motor and no rpm reading, the problem should lay within that circuit rather than from that circuit to the tachometer. Hope that gives you somewhere to start with trouble shooting the problem. Bob

[@torbjorntroell5985]

@@whitedoggarage Thanks Bob, i will start from your advise and hopefully find the issue, Have a nice holiday and enjoy your life. //Torbjörn

[@whitedoggarage]

@@torbjorntroell5985 Thanks and good luck with your repair.

[@conradpaul6100]

Hi there, great video!!! I have the very same bike and having issues with spark as well. My coils are fine as tested them. I'm suspecting the cdi/Ignition box.... How do I test this?

[@whitedoggarage]

Usually a failure there shows up as no spark on any cylinder. I have seen them shut down completely and sometimes come back to life to fail again later, but often just stop working. The ignition box will usually be the culprit here. I am assuming you have no spark on any cylinder. Unfortunately the easiest test is to swap the box for a known good one. Do you have any mates with a similar bike, that will let you swap theirs for yours to see if that is the fault?

[@conradpaul6100]

@@whitedoggarage actually now thatt I think about it, it may actually be a bad coil..... Cylinder 1 and 4 is getting strong spark and cylinder 2 and 3 gives very erratic and very weak spark... Sadly no one near me whom I could swop ccdi or coils with. How would I test if a coil is faulty, swop it with the cylinders that are giving good spark?

[@whitedoggarage]

@@conradpaul6100 Swapping coils is an easy check. I am away from the workshop for an extended period at the moment so I can't look up a manual; but my recollection is that Suzuki coils have two wires going to each of them. On each of the two coils one wire will be the same colour for both and the other two wires will be different colours (I can't be sure, but I am thinking the different wires might be orange/white and black/yellow). You should be able to swap those wires over and the problem should then transfer to 1 and 4, if it is the coil. Hope that helps.

[@conradpaul6100]

@@whitedoggarage hi there.small update.sent all my ignition components to mate with a running bike and all my components were fine but suspect my pick up coils are shot .do you know how to test those with a multimeter?

[@whitedoggarage]

@@conradpaul6100 You test them by checking resistance. Unplug the cable to the pickup unit. Leave the unit on the bike. There are two wires to each side and you measure resistance accross these two wires. I am away from my base until November so I can't check my notes to tell you the value, but I think it is maybe 3 ohms - but that is a guess. Theoretically, it wont be zero because it is a coil, but it wont be two high because it is picking up a pulse. Those coils are insulated from their mounting plate so if you check resistance readings between the wires and the plate it should be infinite. In short low resistance accross the two wires leading to each pick-up, infinte resistance between all wires and the mounting plate. Sorry I could not be more helpful with real world values.

[@markwhalen5300]

6:10 Great Explanation.

[@whitedoggarage]

Thank you

[@joshsutcliffe6099]

What about a bike that has only 1 cylinder that's cold. It's. Got fuel and spark but can hold the head pipe from cylinder 4 after 5 min of running.

[@whitedoggarage]

Interesting question, if I read you correctly, cylinder 4's exhaust is cold after 5 minutes of running. You have checked and the spark plug shows a spark and you belive it has fuel. Spark plugs can show a spark when out of the motor, but because of poor compression or maybe a crack in the insulator may not work in the motor. I have seen this with plug fouling too, where the spark is there outisde of the motor, but the plug wont spark properly in the motor. My first suggestion is to replace the sparkplug on cylinder 4 with a known good one and see what that does. If that cylinder is still cold/cool I think it might be the carby, something like a split in the diaphram, so that the carby flows fuel for idle, but above idle the cylinder is acting more like an air pump. That said, it has to be cold for that cylinder not to get some warmth at idle. Hope that gives you something to look at anyhow.

[@joshsutcliffe6099]

@@whitedoggarage tried new plugs,new coils,,swapped the carbs off of my other bike. "Same engine" it's baffling. Wonder if I should do a compression test maybe a valve is stuck?

[@joshsutcliffe6099]

@@whitedoggarage here is a little background on it. It sat for 10+ years. When my brother passed away I decided to restore it. It ran great for about 100 miles before that cylinder quit. Valve clearance maybe? Man idk lol

[@whitedoggarage]

@@joshsutcliffe6099 Okay, nothing simple then. Yes, having tried all those options a compression test would be a good next move.

[@whitedoggarage]

@@joshsutcliffe6099 If it ran great for 100 miles, it may not be valve clearence, unless the adjuster has let go in some way. Your idea of doing a compression test is a good one, there are a host of possibilities to sort out there including your suggestion of a stuck valve. Sitting for years like that does no engine much good.

[@andriesvanderwalt1849]

Please help same bike but 3&4 running cold no ignition

[@whitedoggarage]

So, as I understand it, what you are saying is that you have no spark at the number 3 and number 4 sparkplugs, but spark at the numbers 1 and 2 sparkplugs. The diagnosis in this situation can get complex. There is a few possible causes. First off, check that the coil leads are not mixed up, one coil should feed spark plugs 1 and 4, and the other feeds spark plugs 2 and 3. If there is a mix up, then connect the leads to the correct cylinders and check again. If the spark is missing from the 1 and 4 plugs or the 2 and 3 plugs then the problem lies with the relevant coil. If so swap the signal lead from the good coil to the bad one and see if you have spark - if no spark, the problem lies with the signal unit - contact me again and I will lead you through that diagnosis. If there is no mix up, for the next step, make sure your starter battery is fully charged - better still connect a 12 volt car battery to your bike battery to add extra power. Check for the leads/caps for cylinders 3 and 4 shorting out to the frame or the motor. I like to check in a dark room where you can see blue or yellow sparks jumping from the leads or the cap. If no joy there, then check for spark at plugs 3 and 4 again. If there is still no spark on 3 and 4, remove the plugs from cylinders 3 and 4 and check for spark using your 'known' good lead for number 1. If those spark plugs spark on that lead, call them good and put them back in the motor. Next step will be to remove the leads from spark plugs 1 and 4 and using a multi-meter set on resistance, push the probes into the two plug caps until they touch the contacts and check the resistance reading. Suzuki specifies that it should be between 31 and 33 kilo-ohms, but I would accept anywhere between 25 and 38 kilo-ohms. Test the leads for cylinders 2 and 3 in the same manner. If the resistance is too high or too low that might be your problem. Let me know how you go?

[@andriesvanderwalt1849]

@@whitedoggarage thanks for information was running fine but with a mis fire now and then but completely dead now

[@whitedoggarage]

@@andriesvanderwalt1849 Not having the bike in front of me it is hard to diagnose the problem, which is why I gave you a logical path to follow to try and solve the problem. But... I can't help thinking the problem might be in the leads or the cap, fine cracks in those can rob you of spark at the plugs and unfortunately give you a plausible resistance reading across the leads. Good luck.

[@andriesvanderwalt1849]

@@whitedoggarage thank you think it's either the connection from ignition unit or one of the pickups on the crank makes sense I think that it's 3&4 cylinders

[@andriesvanderwalt1849]

@@whitedoggarage thanks for your feedback I'm in the UK and it's so damn cold so will check when I get a break in the weather just thought that was a easy one like a coil but as the system is left coil 1 and 3 and right coil 2and 4 can't be that so due to moisture can be the connection or one of the ignition pickups