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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.
Posted by Troll
- January 12, 2013, 11:15:34 AMNo. 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.
Posted by John Hopkins
- January 11, 2013, 19:59:29 PMwow is that another way of saying that it is a CDI system with one plug firing on the ignition stroke and the other firing on the exhaust stroke to burn any unignited fuel..
John.
Posted by Troll
- January 08, 2013, 16:02:45 PMJust a thought..... .08 mm is .032 inch. Fuel mixture plays a substantial role in the spark propagation. the Drifter uses a waste spark system that allows the spark to jump the gap with the lowest resistance. Here's how it works: There are 2 plugs in the cylinder, but they are connected to different ign. coils. When the fuel mixture is burnable, the electrons waiting at the plug's gap are able to ionize the mixture in a localized area, creating a low resistance path that they follow across the air gap. The ionized fuel will easily catch fire, and the process is started. The other 2 plugs are living in a non burnable atmosphere of exhaust gasses. The exhaust gasses cannot be ionized, therefore the low resistance path is not created. This process, essentially causes all (most, not all) of the spark energy to go to the plug with the easiest path. If a plug is wet with fuel, the spark has the ability to follow the insulator down into the plug shell, not across the air gap. This will, essentially take that pair of plugs out of the process. The wider the air gap, the greater the resistance to spark propagation. Modern cars, with their high energy ign. systems produce upwards of 50,000 V at the plug, but even these systems cannot fire everything. I've seen distributor cars eat through the middle of the ign rotor if the plugs are badly enough worn, and coil pack cars (like the Drifter, and most all motorcycles) carbon track the coil pack and wires.
Posted by ChilliDrift
- January 08, 2013, 06:37:17 AMIf that battery is attached and you are using the Jump Pack it will likely cause starting problems. If the battery is removed and it runs and starts fine, It is.. as you know know, the battery. Batteries can do more than just go dead. I think that a shorted cell is your problem.. Some stores will sell you a smaller battery that is technically big enough to start your bike,..and then give you an adapter to increase the height. But the correct battery is worth searching for. IVe found that the simplest solution is often the best with these bikes. THey are tough. With only a few issues that are common.