Can I do a test fire on the CB125 with a 12V battery and 12V coil running total loss?

Maritime

Over 10,000 Posts
OK so the coil I ordered is delayed till the new year, I want to test fire the CB125 to know it will run before we strip it all down and do all the work. Can I hook up a 12V battery and Coil to it and test fire it? I was trying to find coil to borrow but no luck and I really want to fire it up now. I know if I put a 6V battery and 12V coil the Coil won't spark well and may cause starting issues. So to try the 12V I would connect the coil to the bike and points, battery to the coil but not connect the charging system as I just need it to run for a minute from battery alone. What am I missing?
 

Maritime

Over 10,000 Posts
so google gave me this. Any reason I can't do that for a 2 min engine run? and do I bypass the 6V condenser to not hurt it? I know running without one for a long time burns out the points but for 2 min should be fine right? actually I can pull the 12V condenser off the GL as it is not needed with the dyna stuff.
moped-army-8cd1073a70db458dcbaf87625e1bb6e4.jpg
 
Last edited:

iatethepeach

Coast to Coast
Hey Maritime. I'm following your tracker thread and enjoying it. I can't really answer your question, but as an anecdotal data point, I've been running a 12V battery in my SL100 with a XR200 motor and XR200 6V coil for thousands of miles and it works great. Obviously, I do have CDI rather than the old SL/CB/CL point/condenser setup, but I'd say you should go for it. Good luck!
 

iatethepeach

Coast to Coast
Uh, now that I think about it, since my setup is CDI and the alternator is from a XL185, you're better off ignoring what I just wrote! Sorry, I'm still shaking off some morning grogginess over here.
 

Maritime

Over 10,000 Posts
Thanks. The 6v on 12v system works according tk the interwebs but the reverse does not. 12v on 6v won't spark right. I can't see why I can't take then12v battery and a 12v coil and wire them up and fire the bike. Going to try it tonight unless someone tells me abgood reasonnit wont work.
 

teazer

Over 1,000 Posts
DTT BOTM WINNER
Should work fine with 12v battery and 12v coil. We run our race bikes as total loss. I have no idea how voltage sensitive a capacitor is but if it burns out, it doesn't matter if you are going to use a Dyna.
 

Maritime

Over 10,000 Posts
thanks Teazer, not going dyna on this bike but since I did on the GL I can use the condenser off it for the test run.
 

pidjones

Over 1,000 Posts
Noted in your other thread that you might need to ground the other plug output on the GL coil. For a quick test you probably wouldn't even need the condenser It will just chew the points a bt.
 

Maritime

Over 10,000 Posts
Well I hunted and hunted and could not find my old GL coils. I know I kept them as they had new plug caps and still functioned but WTF I put them IDK. Now I need to see if the Scooter coil will work for the test or if I need to pull a coil off the GL.
 

irk miller

You've been mostly-dead all day.
DTT BOTM WINNER
I don't know if I understand the issue here, but you can run a 6v system off a 12v battery. Just run a ballast resistor to drop voltage a bit. I don't remember if these have an electric starter or not, but you can run a 6v starter off of a 12v battery, It will just spin like hell.
 

Maritime

Over 10,000 Posts
There isn't an issue really. I orderd a 6v coil and covid made delivery go from 7 days to 25 and I dont want to pay for another but I want to test fire. So all I have is 12v coils and if you run those @ 6v you get very week spark, so to fix that I will wire a basic total loss ign to by pass the 6v bits on the bike and just fire the 12v coil with 12v battery through the points direct. I just now have to find my old gl coils or pull one off the bike or scooter.
 

irk miller

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DTT BOTM WINNER
There isn't an issue really. I orderd a 6v coil and covid made delivery go from 7 days to 25 and I dont want to pay for another but I want to test fire. So all I have is 12v coils and if you run those @ 6v you get very week spark, so to fix that I will wire a basic total loss ign to by pass the 6v bits on the bike and just fire the 12v coil with 12v battery through the points direct. I just now have to find my old gl coils or pull one off the bike or scooter.
Did you read anything I just wrote? I know you can't get your parts before the new year. I am talking about there being no issue running your 6v bike off of a 12v battery. Any DC coil will work.
 

Maritime

Over 10,000 Posts
Did you read anything I just wrote? I know you can't get your parts before the new year. I am talking about there being no issue running your 6v bike off of a 12v battery.
If I connect it direct into the harness without a resister I blow all the lights, if I put the resistor to protect the lights, and use a 12V coil I'll get shitty spark, the reverse, putting a 6v coil on a 12v battery works but again I don't have a 6V coil. So since I don't have the resistor to reduce to 6v anyway and the 12V battery won't fit in the battery box and I have a 6V coil on order that will work eventually and all I want to do is hear the engine run before tearing down the bike to know if I need to do anything to the engine after tear down or leave it alone. 10 mins wiring it direct with a temp coil and temp battery is what I am going to do. I get what you said and if I was trying to make it a rider with 12V stuff it would be fine.
 

irk miller

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DTT BOTM WINNER
You're right, I've never done this before. And here I thought you were just trying to test fire the engine. Good luck chasing your tail or waiting patiently for your coil to get delivered.
 

Maritime

Over 10,000 Posts
You're right, I've never done this before. And here I thought you were just trying to test fire the engine. Good luck chasing your tail or waiting patiently for your coil to get delivered.
Man who peed in your cornflakes this morning. I agree with you man, but my battery is a goldwing and so is the coil so trying to install those in the bike is not going to happen so I'll wire them temp and just power the coil and points to fire the engine for 2-3 minutes to hear it run before tear down. All I want to know is do I need to open it up and do anything or is it ok to leave it together and run as is. The fact I can run it off a 12V battery with a ballast resistor that I don't have either is a moot point. It may be true but I'll have all the 6V kit when we re-assemble, I wasn't arguing that you didn't know anything man, I know you know a shit ton more than me about bikes. All I was confirming is can I wire the bike that way with the bits I have and it has been confirmed.
 

irk miller

You've been mostly-dead all day.
DTT BOTM WINNER
The only thing on your motorcycle not being run through a regulator is your starter. Bypass the regulator to the 12v coils you want to fire the engine with. The 12v battery won't hurt a 6v starter, but if you don't want it spinning crazy fast, run a ballast resistor. The resistor is for the starter, nothing else. Disconnect the harness and run just the wires needed to for the engine. If you don't care about kick starting it, then don't worry about the starter either. You wrote this long response to my suggestion with a bunch of irrelevant stuff. You're making a pretty simple thing into a very complicated dilemma that doesn't really exist. It's not a pissing in my cornflakes type of deal.
 

Maritime

Over 10,000 Posts
Ok, I gotcha now. There is no starter and I am going to wire it exactly like you said, battery 12V to coil then Coil to points and kick it over with a temp fuel supply. I get long winded with my ADHD brain. Ifi had a starter I would just run it the 12V for the short time I'd need it.
 

Maritime

Over 10,000 Posts
Thanks. I pulled a dyna from the gl. Almost finished wiring to check for spark. If that works Ill set up a temp fuel tank and roll outside to test fire
 

whynot

~~~If it ain't raining, I'm riding~~{iii}?~~prost~
Interesting, I just picked up a CL100, and thinking of doing a full 12 volt conversion.
 

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