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Discussion Starter #1
Okay I have a simple wiring setup. New coils stator battery. I had the bike running before then chopped it down a lot and I have it able to turn over but I have no spark at all. I try to give power to the black and white wires that go straight to the coils and when I do all four terminals(two on each coil) read 13 volts I turn it over and I get nothing. I have a powerprobe and when I'm turning over the bike with the probe on the coil where the spark plugs wires goes it actually start to ground! I have no idea what's going on
 

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1983 Honda vt750 Shadow
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If you have battery voltage on one side of the coil winding, it will also show on the other side until the Ignition control unit grounds the negative side to signal the coil to fire for that cylinder. Like the old points and condenser system that switched the coil to ground and caused spark when in time. But this is a transistorized version of that.
So it should show a blink as it is cranked. If the ignitor unit is working.
But see if there is battery voltage at the black/white wires at the coils and the spark units with the key on and the kill switch on. The kill switch shus off power to the ignition when turned off.
 

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Discussion Starter #3
Thank you for the reply, I'm trying to understand it all I'm not too sure what that means though in a sense of what I've done wrong here. When I had it running before I didn't even have my kill switch hooked up, my kill switch is just the black white wire and I left it out not plugged in and it ran fine. But now no power to coils unless I plug that kill switch wire to accessory power and even then I don't get any spark. I have a relay set up for the ignitor boxes to put full voltage to the coils , I may have a grounding issue I just didn't change much of anything when it was running before. I appreciate the help I'm not very good with wiring much and all I have is a power probe at the moment . I opened the ignitor boxes and everything looks fine . Thanks again
 

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1983 Honda vt750 Shadow
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Strange about having no kill switch in line and it ran. But as long as you have power to the black/whites at the coils and ignition unit that is a big start. Then it is all the spark signal from the ignition units to fire them that is needed. Maybe the ground at the frame is loose or corroded and not allowing the ignition units to work properly, You can never have too many grounds, so you can add a temporary wire to any GREEN ground wire as a test to see if it helps.
 

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Discussion Starter #7
I'll check that too thank you I have a manual downloaded to my phone I'll check what it supposed to be at, I'm uploading a photo on here could you guys tell me what this is. I deleted it off my bike but I'm just curious what it actually did, here a photo of my bike almost done if I can figure out the wiring! thanks
 

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Here is the factory manual in case you don't have it.
The box you took out is the mysterious black box to control the ignition but if it fails and you take it out of the circuit the ignition works just fine. So WTH does it do ???

What is even stranger is that on the manual electrical diagram for the 1983 750 doesn't show it, but the 1984 700 does. BUT my 1983 750 does have it. Called spark unit #2.

 

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Discussion Starter #9
I could not figure out what that box did but I knew it had to do with the ignition and cdi seems how all the wires are for the coils and what not, (black/white, blue, yellow, etc) though I did the very simple wiring when I redone it all and it ran just fine with the two cdi boxes only. I believe I messed up my coils though after I pulled out all the wiring to make it cleaner looking . I tested the coil from the positive terminal ,and to the huh output terminal where the plug boot goes . and did not get any reading at all which I should of had over 10k ohms . I know I messed up with an arc or two and short circuited something but I wouldn't think both coils would have fried but they both do not give off anything when I test them so I guess that's just my bad luck. I opened up the cdi boxes seemed how they aren't the sealed kind and everything looks fine no burns or anything blown so I'm thinking those are okay(I don't know how to test those) I ordered a new set of coils(I use Accel super coils btw) and we will see how it goes when I throw those in. May just be a 230 dollar mistake I made we will find out but as for the mysterious ignition #2 box I guess that will stay a mystery
 

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The coils are not like car coils, there is no connection between the primary and secondary windings. No ohm readings.More like an actual transformer circuit and a waste spark ignition with 2 plugs.
Measure the spark plug caps too. They should be about 5000 ohms each. If they are bad no use putting them on with your new coils. Tell us how the new coils work out, I would like to upgrade my old coils too.
 

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Discussion Starter #11
I was told to test one of the primary leads to one of the secondary leads through the plug wire and it should read around 10k ohms unless I was mislead. If that's the case then my coils might be fine ? When I did that I didn't get any reading at all. I'll check again tomorrow and keep you posted but the accel super coil 140403 are great. I ran it with them for a while and they are great. I like them better than the dynas most people get
 

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Coil testing
 

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Discussion Starter #13
Figured out my issue guys, I wires my cdi boxes wrong fixed that and the accel coils are great. I'm in to another issue now and it when I'm turning the bike over. When I go to give it gas while turning it over a huge clunk noise happens and the it stops turning over and then my battery is too low to crank. Headed in to work now but if anybody knows why this is happening please let me know
 

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If you open the throttle while cranking it does change the sound a lot as the compression goes up. Always try to start with throttle closed. Jump it with a non running car battery for full crank amps you need.
 

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Discussion Starter #15
I can't jump it like that because it's one of those antigravity lithium ion batteries. I'm letting it charge over night on the proper charger. I understand the change is compression noise but this is a loud clunk noise and completely stops the engine from turning over. Just odd that it happens when all im doing is giving it throttle to the carb, yet the clunk sounds like it's the starter getting jammed seems how it stops turning over I don't see how giving the carb a bit of throttle would cause that. Anyway I'll try to fire it tomorrow when it's fully charged and I have some gas in the carb
 

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Then just wire directly to the car battery for the test. If you crank it over with no throttle and full choke, what happens? That loud ‘clunk’ (not a ‘pop’?) is concerning...
 

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Discussion Starter #17
With no throttle and full choke it'll just turn over . Mind you I don't have gas going to it at this point I was just testing it turning it over . I did add a bit of gas though after a while and once I give it throttle it'll clunk almost like the starter gear hit something and stops turning over. I has a good bit of smoke come out the carb after that too . Every time though it's fine cranking but once I hit the throttle CLUNK! . I did it a few times. Tomorrow I'm gonna put it in gear and turn it over see if that changes anything seems how I deleted the neutral safety switch. This has never happened before. Only thing close to what I hear is when I shift while riding from 1st to 2nd it'll make a clunk sometimes but I never cared much but now it's doing it when I'm turning it over when I throttle it is very odd to me
 

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Discussion Starter #18
Found my issue, I put the coil wires on backwards (yellow and blue) . Fired right up thing roars! Needed a bit of adjusting due to the velocity stacks and gravity fed system but it's good to go now. Thanks again everyone for the help. And as far as the coils go I would go with ACCEL 140403s all day. It's a kit comes with wires that you just cut and fit to size only thing I changed on them is I got different caps because I'm not a fan of that salmon looking color .
 

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Good to hear it is running again.
Thanks for the info on the coils too. A bit of money but well worth a better system.
 
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