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Posted by rob f
- April 02, 2019, 08:07:06 AMMitt: i am retired so don't have any life worries. Also the more that i help you the more I learn about my own bike so we both win, I hope.
i have a good knowledge about basic wiring and functions but not so much in the electronic stuff like resistors,ECU, transistors etc. from what i can understand now about this bike is that the ignitor box has to have a lower voltage signal from that gray wire (5.7 v on my bike). I am not sure why the oem gray wire starts large from the key switch and then goes small at the connector. But the important thing is to get that 5v on that gray wire and i believe this is what https://www.vulcandrifterriders.com/forum/index.php?topic=3625.0 means when he says the resistor is important.
If your starter works then the brown wire curcuit is ok. Did you test for 12v with key on at the red wire on the coils? The front cylinder is easy to check.
If you have 12v, then you need to pull out the front spark plug, hook the sparkplug wire back on ,ground out the sparkplug body against the engine , turn over the starter and check for spark. Don't hold the sparkplug with your hand. Right now you are guessing that you have no spark but you need to find out for sure!
I know that this is a little extra work but could save a lot of worries if there is spark.
As far as the wire sizes i personally would try to stay with the OEM sizes. Not sure how a different size on the gray wire would affect the 5v
I hope that you are not offended by the way i give you instructions. I do not know the level of your skills so I have to treat you like a first year apprentice. i am trying to help you avoid mistakes that I personally have made when I was learning.
Posted by mittico68
- April 02, 2019, 01:46:24 AMRob, first of all I really appreciate all your efforts to help me solving the issue(s) I'm facing, as I guess you've got your own daily problems to solve... 
Now, to answer your questions:
- even though it doesn't matter anymore, I can assure you that the kick stand is on and the gear is in neutral;
- the starter turns on, as I push the starter button, but the engine doesn't fire up;
- the resistor (a very small one) is inside the OEM key switch: you can see it, by opening the black cover (you gotta unscrew 2 little screws).
That said, there's something that makes me mumble: could the issue depend on the fact that I used wires of different sizes to connect the HD switch to the OEM harness? I mean, I used a 2.5 (mm2 - 13 gauge) for the gray + brown wires connection and for the white wire, then a 1.5 (mm2 - 16 gauge) for the red/blu + red wires.
Posted by rob f
- April 01, 2019, 11:54:34 AMJust came back from doing some tests on my 800.
Here is what i found:
With the key on:
there is 12v at the red wire of the coils
there is horn, starter, signal lights, tail light ,brake light, no headlight( but it comes on as soon as i hit the starter button)
Interesting about the gy wire, I tested it at the key to engine harness connector and it has only 5.76v. i notice that the gy wire is about a 14 gauge on one side of the connector and gets smaller(18or20gauge) at the back of the other connector. I beleive that you and Greenbarn have been talking about resistors in the gray wire. This could be your problem. Somehow that gy wire gets cut down to 5.76v . Nowhere in my tech manual does it show this, but that's what my bike says. You had mentioned that the OEM switch has a built in resistor . How did you find that out?
The kick stand safety switch works with the neutral switch, so as long as the bike is in nuetral this is not our problem.
I also found that I had given false info way back when this topic started so i will correct this now. It is not relevant to our issue right now but still would like to address it.
I had stated that the brown wire at the key switch is only live when the engine is running. This is false,as it is fed by the live white wire at the key switch. I was reading the electrical incorrectly. My apologies.
Seems like I am learning as we go along too.
Posted by rob f
- April 01, 2019, 08:57:39 AMok, I was going to ask about the kill switch also but that's been eliminated. Gotta ask some simple questions first to narrow things down. When you say the bike doesn't start do you mean that the cylinders do not fire or that the starter does not turn? If the starter works ,then did you actually test the sparkplugs for spark yet? Also is your kick stand down? There is a safety switch on it. In neutral?
I know this is all simple things and sure that you have done it but i have to know for myself.
Looks like both the br and gy wires end up in the igniter box. The gy goes there directly and don't see any resistor it that circuit. The br wire ends up going to the igniter box, alt , and the fuses that feed the headlights, turn signals,tail light,horn and ignition system.
The ignition curcuit is fed 12v in by the brown wire from the key through a 10 amp ignition fuse and then out by a br/w wire up to the kill switch starter button and then to the coils by a red wire. If your starter works then the whole curcuit from the battery to the key through the fuse box is ok and doesn't need testing. Could be in the kill switch itself and an easy test is to check for 12v at the red wire at each coil when key switch and kill switch are on. I will test this theory out on my own bike today just to make sure.
If there is power at the coil red wires then the power side of the coils are good. Which means it's the signal to the other coil terminal is not coming from the igniter box My manual only shows a 12vcheck at the igniter box at the br/w wire. There is very little info about the gy wire that goes from the key switch directly to the igniter box. i am assuming that it should have 12v to the box but in the HD key conversion posts they say that it is important to have the resistor in.
Your brake light could be related or separate so lets get it running first and deal with this later.
Posted by mittico68
- April 01, 2019, 01:36:33 AMTroll, thanks for those diagrams.
And, as already stated above, the kill switch was ON while attempting at the damn thing...
TFrank, I'll keep you posted, for sure.
Posted by mittico68
- April 01, 2019, 01:33:31 AMQuote from: rob f on March 31, 2019, 09:17:52 AMAre you familiar with Dc volts and continuity testing? Basically we will test the HD switch to see if it has continuity across the terminals and then we will test for voltage at the wires at different locations. If you have the wiring diagram I sent you, it will help a lot. Looking at the whole diagram seems a little scary so what I sometimes do is , clear my mind, get a copy of the diagram and then with a colored pencil trace each separate circuit with a different color. If you start tracing from the switch harness right down to the battery it will start making more sense in your head as you follow the wires on the page. Just focus on one circuit at a time.
I must go now and will check in tomorrow.
I've got a volt meter and I've tested each and every connection for 12v continuity: everything was ok, with the HD switch in the IGN position and the OEM kill switch ON, too.
I've also got the 800 OEM Service Manual, and I'll do as you suggested for the colored diagrams.
So now, all I need is your kind HELP! 
Posted by Troll
- March 31, 2019, 21:27:36 PMHere's a couple of wiring diagrams. Just a silly question, but the kill switch is in the on position, right?
Posted by Tfrank59
- March 31, 2019, 20:43:14 PMQuote from: mittico68 on March 30, 2019, 13:21:25 PMThis really isn't my area so I'm just going to have to sit back and let Rob and others help you. Keep us posted though.Bad news.
After double checking all the connections of the whole damn thing, I've tried to fire up the engine.
No way, it doesn't start.
I've even bypassed the resistor, resultless...
And, if ever it is enough, I've also noticed that even the brake light doesn't work!
So, am I at a dead end?
I don't wanna give up, but I really need your help.
Posted by rob f
- March 31, 2019, 09:17:52 AMI"ll try to help you out Mitt but only have a little time this morning.
I think that you said that you went out and bought a volt meter. We will need one. Does it have an Ohm scale? Are you familiar with Dc volts and continuity testing? Basically we will test the HD switch to see if it has continuity across the terminals and then we will test for voltage at the wires at different locations. If you have the wiring diagram I sent you, it will help a lot. Looking at the whole diagram seems a little scary so what I sometimes do is , clear my mind, get a copy of the diagram and then with a colored pencil trace each separate circuit with a different color. If you start tracing from the switch harness right down to the battery it will start making more sense in your head as you follow the wires on the page. Just focus on one circuit at a time.
I must go now and will check in tomorrow.
Posted by mittico68
- March 30, 2019, 13:21:25 PMBad news.
After double checking all the connections of the whole damn thing, I've tried to fire up the engine.
No way, it doesn't start.
I've even bypassed the resistor, resultless...
And, if ever it is enough, I've also noticed that even the brake light doesn't work!
So, am I at a dead end? 
I don't wanna give up, but I really need your help.
Posted by mittico68
- March 29, 2019, 02:34:46 AMGot it.
I'll try and see what happens...
Posted by Troll
- March 28, 2019, 16:17:29 PMcan't hurt to bypass it and try. The idea of the resistor is to send a specific voltage to the "unused" port on the injection ECM that verifies that the ign. switch hasn't been bypassed.
Posted by mittico68
- March 28, 2019, 11:21:49 AMQuote from: Troll on March 28, 2019, 07:47:30 AMThe resistor is for the fuel injected models...can't see why you would need it at all on a carbed model
Never thought about it... 
That said, I also remember that the OEM ignition switch has got a resistor soldered inside, on the gray wire...
So, do you think it could affect the whole thing?
Posted by Troll
- March 28, 2019, 07:47:30 AMThe resistor is for the fuel injected models...can't see why you would need it at all on a carbed model
Posted by rob f
- March 25, 2019, 07:47:51 AMFirst thing that I would do, is if you have a spare set of plugs, pull the sparkplug wires, hook in the spare plugs, ground the spark plug body to a good ground and then crank it over. This will tell you if they are getting spark or not and take the guessing out of it. Could be fuel related.
Greenbarn is correct about the crimpon connectors. Soldering is the best , but untill you get it working properly, the crimpon is at least reversible. Soldering not so much. However, I have run into 3 way crimpons a lot on farm equipment and most of them were fine. Di-electrical grease and tape also helps.