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Discussion Starter #1
Hello to everyone out there. For the past few months I've been hard at work building a 83 shadow and I can see the slightest glimpse of light at the end of the tunnel.

The issue I'm asking about today is spark! (oh boy!)
But first I'll lay out my setup.
I made my own wiring harness (which I suspect where the problem is lingering)

I do have spark on all 4 plugs. Coils read 3.7 ohms across the small connectors. I have a fuel line running from tank to carbs, no petcock on tank, just a small inline valve halfway through. Good charge on battery. So I'm getting spark, the occasional backfire tells me im getting fuel, but it never acts like she wants to crank.
What my question is, If my wires are mixed up going to the spark units could I be firing on one cylinder when the opposite is getting fuel? If so, anyone have a way to determine how to wire this thing up. On one side i have 2 whites and 2 yellows (coming out of spark units), and the other side i have 2 white, 1 yellow, 1 blue. (coming from engine case)

On a sidenote, I do not know the history of these carbs, they were bought on ebay after fighting with a torn diagphram slide in the originals. I have not been inside of these yet.
 

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There should be a timing index and marks on the flywheel; the marks should indicate which cylinder should be at TDC when the points for that one just start to open. Look to see which set of points begin to open when the index is at a fire mark and follow the wiring to the coil, to see which spark plug it getting the spark. Verify that cylinder is at TDC with the valves closed on compression.
 

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Discussion Starter #3
I was considering timing but decided against it since i havent touched it and it was running. Ill have to take a peek.
 

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You asked how to determine if the spark system is wired wrong. Has it run since the wiring was replaced?

Are the 'spark units' electronic ignition, and just triggered by the points? Usually, when you have points, they switch the coils, and there are condensers connected across the points.

NVM, I just found a schematic, and you do not have points, you have pickup coils that trigger the electronic ignition modules (spark units).
On one side i have 2 whites and 2 yellows (coming out of spark units), and the other side i have 2 white, 1 yellow, 1 blue. (coming from engine case)
The sensor yellow wire is from pickup #2, and the blue wire from pickup #1. From the spark units, the yellow output goes to coil #2, blue to coil #1. That leaves the question, how are the cylinders numbered? Suzuki calls the rear cylinder #1, but I don't know about Honda.

In any case, you can't look at points to determine which coil is firing, so need a light to see which timing mark is lit when the spark is triggered. I would assume the flywheel has timing marks, so you just need to determine which mark lines up for which cylinder at TDC, and verify the light flashes at the right time.
 

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Discussion Starter #5 (Edited)
Thanks for that info. Both (spark units) have a blue as output to coil. According to original wire diagram one does change to yellow. The bike has never ran with this harness.
Popped timing cover off, got three marks, one being "IF" one "F" and "FI" (or something like that) in that order. With the front cylinder at tdc the mark lines up with the "f" . So i think im good there unless im 180 out somehow.
Got to looking at original wiring diagram while i had it out and saw a black coming from voltage reg that ties into ignition. Looked at bike, my black was taped up not going anywhere, i was just running alt and starter solenoid. Tied black into switch and she sputtered a few times with known bad carbs. Swapped carbs, put exhaust back on and tank. Low battery. Waiting on a slow charge. But we sputtered a little!!

EDIT: None of this rules out that I'm out of time or not firing at the right time. No timing light in my collection yet. But I now know nothing jumped enough to kick me off TDC
 

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You can get a timing light for 20 bucks and up
 

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Discussion Starter #7
Oh yeah. I lived on my bike and drifted for a few years so my tools were cut majorly to the bare necesseties. Now that im settled its a slow progress rebuilding my stash. :\ a buy as you need basis
 

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Discussion Starter #8
Nice to see ya floating around critter!
Update- After a slow charge I tried to crank the bike. She's firing now, occasionally letting you give it some gas but never running without the starter being engaged, (i never forced the bike to run with starter engaged) Did some tests on the starter relay, with starter engaged im getting 9.3 V on both sides of solenoid. But I'm getting a crazy OHM reading across the terminals (without starter or battery wire attached) but starter button engaged. It's my understanding that this is suppose to read 0 at that time. Let battery charge for a bit longer, tried it, had it firing a few times on its way out after releasing the starter button. A timing light is on the list to get this weekend. Until then I'm riding on hopes that since this bike has been in pieces and boxes for the past 8 months, she's just hard to get that first start.
Sorry for the novel but it's in hopes to help both myself and whoever may find themselves in this situation.
 

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Did some tests on the starter relay, with starter engaged im getting 9.3 V on both sides of solenoid. But I'm getting a crazy OHM reading across the terminals (without starter or battery wire attached) but starter button engaged. It's my understanding that this is suppose to read 0 at that time.
Your battery has a very weak or dead cell - I think you're beating a dead horse, trying to charge it.

One would expect 0 Ohms when the solenoid is activated, but, over time, the contact resistance at low current (that of your Ohmmeter), goes up with each high-current use. Since you had essentially the same voltage on both terminals when actually drawing current, I wouldn't worry about the crazy readings.
 

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Discussion Starter #10
Fair enough. It wasnt long after that i tried a few more times and she finally busted off. Even idled for about twenty seconds. Needs rejetted and tuned but im,feeling,better.
 

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You know, you can use cables to jump your battery to that of a non-running car or truck, just to get that problem out of the way.
 

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Discussion Starter #12
Oh yes i am aware winter and thank you kindly for thw input. It may not be proven but i feel like im being less abusive to the battery and electrical system by slow charging.,and plus. I dont have a car or truck, only bikes. Ha. She sounded good last night idling, charging system seems to be working so maybe i can put the slow charger away for a while.
 
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