Motorcycle woes - Page 1
Forum section: electronics / repair

author: joeqsmith
author_rank: Super Contributor
timestamp: April 21, 2020, 12:17:17 am
content: I bought a brand new 1994 Suzuki motorcycle. This was my first liquid cooled bike. It never ran well if the temperatures fell much below 45. At 40, it would seldom start. I just assumed the engineers in Japan had no idea we would try to ride their products in the snow. It typically required new plugs every season if I used it at all in cold weather. Last year, it dropped a cylinder. It's in inline four, two coil with wasted spark. I put a new set of plugs in which seemed to cure it. Ran it for a while and again, one cylinder dropped. I noted which one was out, pulled that plug and drove it a while. Then it dropped out again. This time it seemed to be the opposite side but I wasn't sure. I figured it was a brain fart....I noticed with a bit richer mixture, it would pick right up. So I went down the path of looking at the fuel and air intake system. Eventually, it got to the point I was certain the problem was the two outside cylinders and had a look at the ignition system. I couldn't find anything obvious but over time the problem got worse. Eventually, I bought a used set of coils and swapped one in. I rode the bike until Winter came. I've now been riding it in colder weather than it would have ever run it when it was new. It's warms up much faster and has not fowled a plug.Finally today I had a look again at the suspect coil. I thought for sure the output was breaking down to the chassis and I would need to check it live in my pressure tester. It turned out I could now see the secondaries resistance was half. In all my years of riding bikes, this is the first coil I have had go bad and I suspect it was bad for all of these years. The coils are potted but I would like to see what finally happened to it to get half the resistance.Ever see an ignition coils secondary fail on a factory stock grocery getter?

author: SilverSolder
author_rank: Super Contributor
timestamp: April 21, 2020, 01:19:36 am
content: Typically what happens is that an internal short develops, so part of the coil is simply by-passed, effectively (hence, half the resistance).This is not an uncommon problem.

author: maginnovision
author_rank: Super Contributor
timestamp: April 21, 2020, 01:38:14 am
content: I'm not familiar with the bike in particular but a failed coil is definitely not uncommon. I've seen a lot of vehicles(100's) have intermittent coil issues(under high load after full warm up causing intermittent misfires) turn into a permanent failure though. I've never found any specific reason for the failures. I've always made sure to keep coils to their cylinders for this reason. Happens once it's a fluke, happens again it's worth the time to check it. In this case it may not have been great to begin with but I doubt anyone would've really taken note of it when new, and after that it just becomes a characteristic of the bike.

author: Gregg
author_rank: Super Contributor
timestamp: April 21, 2020, 03:24:35 am
content: Coil failure was just one of the many failings of Lucas electrics on older British motorcycles.

author: joeqsmith
author_rank: Super Contributor
timestamp: April 21, 2020, 06:08:59 pm
content: You can see how the coil form is made. The raised area of the form is where the one high voltage wire set is routed. Note there are five strands in the secondary. For the resistance to be half (measured 15.26K, spec is 30K-40K, good coil measured 36.69K), I would think it would have had to break down in that longer wire that routes across the length of the form. But you can see they have a lot of spacing in this area. No signs of air pockets in the potting.

author: SilverSolder
author_rank: Super Contributor
timestamp: April 21, 2020, 07:02:23 pm
content: Awesome pictures!What did you use to make such a clean cut?

author: joeqsmith
author_rank: Super Contributor
timestamp: April 21, 2020, 10:25:41 pm
content: Quote from: SilverSolder on April 21, 2020, 07:02:23 pmBand saw, followed with some 200 grit and finishing up with some 400.

author: m3vuv
author_rank: Super Contributor
timestamp: April 23, 2020, 08:35:42 am
content: reminds me of an old bsa a10 i had years ago,would always die when hot,had a good spark with the plugs out of the head but not enough umpff under compression,ended up getting the magneto rewound,that curred it.

author: CaptDon
author_rank: Super Contributor
timestamp: April 25, 2020, 07:58:39 pm
content: Coil failure was very common on the old crossflow Evinrude outboard motors.I had an SL175 Honda Street/Trail bike that I finally gave to a motorcyclesalvage dealer. It was one coil serving two cylinders with wasted spark. Thesecondary floated above ground with no center tap!! The spark would nevershare correctly between the cylinders. It constantly would develop a miss andthen drop a cylinder entirely. I tried wide gapping, narrow gapping, combinationsone wide one narrow, and borrowed a coil from a buddy. Nothing would makethis bike run right. Carb mixtures were fine, advance worked as it should. Thebike had suffered some minor damage in a friends garage fire. I just finally gaveup on it.

author: Wallace Gasiewicz
author_rank: Super Contributor
timestamp: April 25, 2020, 09:23:29 pm
content: As college students my friend and I both had English cars,I had a TR4. Our observations were that the Lucas ignition systems would only work fine when the weather was dry and sunny. They worked extremely well under those conditions. The cars would not start under cool humid conditions most of the time.We concluded that England must be a dry and warm place.Later I visited England and was quite surprised to observe that the weather was cold and rainy.It was during the hurricane of 1979.I had to conclude that my former logic was dead wrong about England's climate.Wally

author: CaptDon
author_rank: Super Contributor
timestamp: April 26, 2020, 07:13:41 pm
content: Why do English drink warm beer, because Lucas also makes refrigerators.Lucas 3 position headlight switch, Dim, Flicker, Off.Lucas 3 position wiper switch, Shudder, Stall, Off.Lucas headlights don't emit light, they suck dark, when theybecome full of dark (all black inside) they must be replaced.L.U.C.A.S.= Last unit cracked and smoked!

author: joeqsmith
author_rank: Super Contributor
timestamp: May 02, 2020, 01:14:15 am
content: Quote from: CaptDon on April 25, 2020, 07:58:39 pmFloating the secondary is common for the bikes I have owned. Your description is similar to what I was having. One plug would foul and the other would run. Replace the fouled plug and the other side would foul. The factory plugs for this bike are an NGK-R CR9EK which is a bit of an odd ball. After changing the coil pack, I have continued to run the bike in colder weather than it has ever been able to run in since it was new.Really, outside of this coil and having to replace the water pump, the rest has been normal, tires, brakes, chain and sprockets.It looks like your old bike used points. Did you ever swap these and the condenser out? Maybe there was too much drop from the battery to the primary? I bet you could fix it now.

author: Old Printer
author_rank: Frequent Contributor
timestamp: May 02, 2020, 01:37:29 pm
content: Not long after I bought my first car, a 1964 MGB in 1969, a mechanic friend of my fathers stopped by while I was trying to get an ignition problem sorted out, never did by the way. He looked under the hood and said “ Lucas - Prince of Darkness”. Cars turned to motorcycles and several Triumphs, BSAs, and Norton’s later I found out what he meant. I also learned to park them over a tray of kitty litter. Sexy looking bikes, but damn...

author: joeqsmith
author_rank: Super Contributor
timestamp: May 02, 2020, 10:40:08 pm
content: I've mostly owned Japanese bikes. I had a Hodaka, Harley Davidson and two Triumphs but all of my other bikes have been from Japan. The last bike I built is mostly made from parts produced here in the USA. Even much of the power plant is made here. Outside of the crankshaft, head casting, engine cases the rest is custom. Still, we would call it Japanese bike. They are a lot of fun.

author: Old Printer
author_rank: Frequent Contributor
timestamp: May 04, 2020, 03:37:31 am
content: Right Joe, I had plenty of them as well. Honda taught us what what a well engineered and built motor vehicle could be. Somewhere around 1990 my cousin and I went to the motorcycle show in New York City. He had a Harley Sportster in college and was determined to get a new one. We sat on a few from 900 to 1200 and they all felt narrow and top heavy, very awkward. We went to the Honda booth and sat on some Shadows. Night and day. They felt balanced and well thought out, everything was where it should be. He bought one the next day, a Goldwing a few years later, and has never looked back.

author: Heatsink
author_rank: Contributor
timestamp: July 02, 2020, 01:56:52 pm
content: Joe - Are you still there? I just came over this and it's highly interesting for me. I have a similar bike, GSXF1100 from 1993. I rarely use it and ever since I bought this bike, it has been plagued by dropping 1 or 2 cylinders, especially when cold or stored for a while. I focused on the carbs since I always saw spark on all 4 plugs, had some improvements but never got really rid of it.Now, reading this I just pulled the coils, resistance is around 14K from 1 HV cable to the other. Infinite resistance to ground. Both coils give similar results. They are labeled Nippon Denso 33420-48B00 and look identical to yours. This is without the spark plug caps. 3 of the caps have an internal resistance of 10K and one has 30K, so one cap seems to be bad.Did you measure yours with or without caps?

author: joeqsmith
author_rank: Super Contributor
timestamp: July 02, 2020, 03:02:03 pm
content: The manual shows 30-40K plug cap to plug cap. 2.4 0 3.2 ohms on the primary.The secondary broke down on mine. It must have been slowly changing over time. Looking at the second coil from the used set I bought, the cap measured 11.08K. The coil without the caps measured 15.34K.I ride this bike most days and even at the start of the season, I had no problems running it just above the freezing point after changing out that one coil. It was a an odd failure for me.30Kohms for just one cap is way out. I assume you tried to measure it a few times and tried to scrape off some any oxidation. If so, it sounds like you have found your problem and now just need to locate a new cap.

author: Heatsink
author_rank: Contributor
timestamp: July 02, 2020, 04:15:58 pm
content: Thank you for your fast reply. Your coil measurements roughly coincide with mine and it seems that the cap with 30K is the culprit. It has no visible oxide or defects. The bike has only 11K miles, I rarely ride it since my KTM is better suited for the roads here (Costa Rica). Nevertheless, the power and smoothness of the old 4 cylinder Suzuki is a lot of fun.l'll change all caps and will look for ones with lower internal resistance. I hope that helps for a stronger spark. The spark is difficult to judge by eye, but it always seemed weak to me. On all cylinders. I am glad that your post brought me one step further. Thanks again.

author: Seekonk
author_rank: Super Contributor
timestamp: July 02, 2020, 05:56:47 pm
content: I got into ignition for a while. I designed a circuit to replace the entire spark control in the old SUN Distributor Tester. Gave it an added feature where it would flash not only when the points opened, but when they closed again so dwell could be measured directly. Found an interesting youtube video where the spark plug was installed into a pressure chamber and they tested it at various pressures. Increased pressure requires much higher voltage. Another video compared coil packs from various manufactures. Guess what, not the same performance. Impressed that a car guy knew how to use a scope!

author: joeqsmith
author_rank: Super Contributor
timestamp: July 02, 2020, 07:07:30 pm
content: True about the pressure. I've had problems in the past because of it. I made up an test jig with a chamber to try different components on. Eventually, like my icon shows, it will follow the outside path.Quote from: Heatsink on July 02, 2020, 04:15:58 pmI really like the inline fours as well.I tossed out the old caps or I would have sectioned one up for you to look at. Mine was always the two outside plugs which share a coil. It would run fine on one side, then it switch to the other. Sometimes both would run fine. I suspect it was a manufacturing defect as it never ran in cold weather and would foul the plugs. It's like a whole new bike now.

author: vk6zgo
author_rank: Super Contributor
timestamp: July 03, 2020, 01:43:00 am
content: I had a Holden Camira (1980s GM "J series world car").It had Bosch electrics, so I never anticipated "Lucas-like" problems, but they happened!On one occasion, it refused duty after I had just stopped at a shop for a cold drink.-----No spark!On investigation, I found that, unlike all others I had seen, the rotor button wasn't a direct connection, but had a resistor embedded in between the centre & the part that "distributed" the spark.In fact, this no longer had a resistor, just a "pit" burnt into the bakelite.What the hell to do?I happened to look down, & there was a discarded cigarette packet, so scrunching the foil up, I rammed it into the pit, the car started & ran OK, getting me home.On another occasion, it was a wet, winters day, & it again refused to start---this time the coil was extremely hot.There were puddles of water all around, so I went through half a box of tissues, wetting them & draping them around the coil.After about 10 minutes of this, it cooled enough that the car would start, & it stayed cool long enough to get home.It was cool enough next morning to run till I got to the car parts place for a replacement coil!Another time, we were sitting at the petrol pump at a country Service Station, when after paying, the car refused to start.This time, it had "eaten" the distributor brush!Luckily, this was an "old school" place, so the proprietor & I sifted through his junk box till we found a brush that would fit, & we were on our way again.

author: joeqsmith
author_rank: Super Contributor
timestamp: July 03, 2020, 03:15:18 pm
content: I would imagine in many cases we have better cooling with the bikes than you would see with a most cars which helps. I owned a Kawasaki Mach III that had a distributor and CDI. It used gapless plugs that were constantly going bad. I had expansion chambers on it. It was loud but very quick! It handled like crap, had poor brakes and we didn't have the tires we have today. Not a starter bike.

author: Heatsink
author_rank: Contributor
timestamp: July 03, 2020, 08:17:58 pm
content: I had a Kawasaki 750 H2, I think it was also called Mach IV. It had already fully electronic ignition, but fouled the plugs anyway. And a 12V 35W headlamp, you could only guess what was in front of you. Besides that it was, like you said, loud, fast and poor handling. Yet, I would love to get it back. The Kawasaki triples are almost collectors items now.