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Posted by Aaron Mitchell
- January 28, 2013, 05:51:26 AMHaven't had time right check the thread or the coils yet but I tried the exam jumper wire when I was ha king Trouble and it gave no codes
Posted by chief
- January 25, 2013, 18:12:59 PMDid you ever do an ECU check? These don't just "throw" an error code, you have to make it show you the codes... if there is a coil problem that would show up in that check.
Posted by 49Reo
- January 23, 2013, 14:36:08 PMIs it possible this problem could be a failure of the electronic ignition system? I am not familiar with the technical aspect of the ignition system on these bikes, other than that it is electronic. Years ago, on a 1977 GMC pickup I had, it started to run rough, then one cylinder dropped out; running on seven cylinders. Everyone said "oh, no, can't be the ignition module, they either work or don't." Well, I had a spare, so put it in and all was well. Just food for thought; some one like Troll or Chief could probably give a definitive answer on the electronic ignition question.
What do you think, guys?
Regards and such,
49Reo
Posted by chief
- January 23, 2013, 14:21:36 PMMy "bad" NEW battery tested fine on the bench, but failed under load. That is VERY rare on a new battery, but you cannot discount it until its load tested.
Usually the cause for weak spark is a bad coil, but you REALLY want to inspect and test everything before you assume you have a coil problem. Good time to get a repair manual... there is an ignition system troubleshooting guide in there.Posted by DC
- January 22, 2013, 06:51:04 AMSo it has to be an ignition problem then?
Posted by Aaron Mitchell
- January 22, 2013, 04:07:54 AMThanks, ill give it a shot, anyone know what the resistance of the plug wires should be?
Its a brand new agm battery (manufactured 12/12), i checked it before i left the store (with a midtronics tester, the same as i have at work)
Posted by chief
- January 22, 2013, 00:01:17 AMweak spark...? (I replaced a battery a couple of years ago and still had problems... the NEW battery ended up being bad. ) If you aren't getting a nice fat blue spark in properly gapped plugs - and you don't think its the battery... check the plug wires and plug caps. A lot of times these can be faulty without outward signs. There is some reason why your ignition system isn't delivering good spark to those plugs.
Posted by waltervl
- January 21, 2013, 04:57:58 AMJust a thought: When starting with extra battery (jump start) is working but without not, perhaps the wiring to the spark plugs is failing somewhere? Did you check that?
Posted by Aaron Mitchell
- January 21, 2013, 01:41:26 AMngk DPR6EA-9
Posted by chief
- January 20, 2013, 15:18:03 PMwhat plugs are you currently using?
Posted by Aaron Mitchell
- January 19, 2013, 01:05:32 AMFirst chance to reply i've had.
Replaced the battery but it still wont run with the proper gap on the plugs. It runs great a .04 gap but getting any start bigger and she wont start.
I've considered trying out those pulstar plugs
http://www.pulstar.com/
http://shop.advanceautoparts.com/webapp/wcs/stores/servlet/product_pulse-spark-plug-pulstar_10038707-p?navigationPath=L1*14931
Posted by Troll
- January 13, 2013, 10:53:09 AM In theory, it should not be, but in practice, it is. The funny thing is that the spark jumps from the ground electrode to the center on one plug, and from the center electrode to the ground on the other...waste spark is what it's called, and for good reason...but the whole point I was trying to make is that if the plug that isn't on compression is shorted out, the spark will go to that plug rather than the one it's supposed to, effectively killing off the spark from the whole coil. 800s have one plug per cylinder, 1500s have 2, but the 1500s will run with one plug disconnected, as long as the wire is not grounded. A wet plug will ground the entire coil output.
http://en.wikipedia.org/wiki/Wasted_spark
Posted by John Hopkins
- January 13, 2013, 09:21:08 AMThat all makes sense..and I don't want to turn a good discussion into a dissagreement, it is great talking to someone who knows something, but The spark is still generated on the exhaust stroke whether it dies or not and as the exhaust stroke should have the valve open there should not be so much pressure that the spark will die too quickly to ignite any existing gasses..
As said I don't want a big argument and I have worked on theory in the past which doesn't always allow for real world situations..manufacturers will always look for the cheapest way to get the job done and firing the plug everytime on the exhaust stroke will save the cost of a fuel sensor.
And now I surrender to your superior knowledge..
John.
Posted by Troll
- January 13, 2013, 08:35:49 AMIt's all about electrical resistance. The leaner the mixture, the harder it is to ionize, and the less likely it will create a path that the spark can follow. I found an oscilloscope pattern of a plug firing. The initial spark gap energy requirement is around 10,000 V, and the burn voltage, which lasts for about 2 milliseconds, is about 2,000 V... I hope this will illustrate the actual electrical happenings. Keep in mind, the compression ratio, amount of burnable fuel, and the mixture (different) and combustion chamber temp. will all effect spark propagation. The spark gap testers people use, with a high output system will easily jump a 1/2" air gap in normal room air, but when put into a compression situation, the spark can go out completely. We used to test plugs in a machine that measured voltage needed to propagate a spark against air pressure. You could take a brand new plug out of the box, and given enough pressure in the test chamber, put the fire right out. You watched it through a little window, when the spark started to flutter, you checked the V against the P to see if the ratio was acceptable.
Posted by John Hopkins
- January 13, 2013, 07:47:50 AMQuote from: Troll on January 12, 2013, 11:15:34 AMWouldn't that mean that they will fire on the exhaust stroke anyway..allowing that the fuel has entered the combustion chamber as it should.No. actually, it's not. If the exhaust cycle is complete, there will be no spark at all on the exhaust stroke cylinder, but if there is any burnable fuel left over, there will be some. It's not intentional, just a fact of electrical flow properties. Since there is no compression on the exhaust stroke, any fuel that gets burned produces no power, just a little flame. This system has been around since the late 'teens. Any twin with one set of points to trigger the coils has used it. Modern systems, falling under the newer emission laws, have gone to a "single fire" type of system. This is a shot of my '78 hotrod ElectraGlide the day I sold it with a Dyna SingleFire ign system. Each cylinder is fired by it's own coil, both plugs at the same time. There are 2 electronic pick-ups in the system, each timed separately, connected to it's own coil. This is the way that the later systems that have to meet stricter emission standards with feedback injection are set up. I did it to the Harley because it let me adjust the timing to minimize pinging with a 9.5:1 compression ratio in a world of poor quality fuel. The Drifters are not feedback, but rather, a mapped system that does not adjust for exhaust content.
John.