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Discussion Starter · #1 · (Edited)
I bought a 1983 honda cm 125 twin cylinder (to convert into a cafe racer) with most of the parts missing. The bike come originally in 6 volts. I wanted to convert it to 12 volts so that I could install new lights and stuff. So I bought new parts which are 12 volts(rectifier,starter relay,flasher relay,signal lights,brake,head light,battery, speedo,odometer) but fixed a used 6v wire harness of a cb 125 because i heard there is no difference in the 6v,12v harness.The local mechanic fixed all the parts and the bike was running fine for 2 about days.The power of the headlight was not enough(couldnt see a thing).The next day while on the road the spark plugs kept misfiring. the plug top was very hot and burnt. after some time smoke came from under the fuel tank. the smoke was from the ignition coil. I fixed only 1 ignition coil given by the local store which he said was 12v which had 2 outputs to the 2 spark plugs. My question is why did it burn? I did not change the stator or anything inside the engine. The original stator, breaker points(in good condition) and condenser(in good condition) are still in there. Should i change the connection? Should i add 2 ignition coils with 1 output(spark plug wire) each and add 1 condenser to each change the stator to 12v? or should i change the point ignition to electronic ignition by adding a pulse unit to it and connection it to a cdi unit(there is no cdi unit in the original 6v cm 125):
1. How many ignition coils should i have? ( them having 2 or 1 spark plug wires, them being 6v or 12v, them having 1 or 2 condensers)
2. What parts should i change (fix a 12v stator and change other parts inside the flywheel?)
3. Should I change the ignition type (keep the point ignition to switch to a electronic one?)
4. If changed to a electronic ignition (what things to fix and what things to remove?)
5. How the ignition should work and should be connected ( from the stator all the way to the spark plugs)

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Sensei
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You have asked a lot, so it may take a few replies to answer all your questions........

#1 IF you only have one points assembly, you only need 1 condenser and 1 dual output (two plug wires) coil....
All should allow for the battery voltage, so 12 V battery, 12V rated coil

#5 The ignition circuit is thus : Battery positive through main fuse TO ignition (key) switch.... ALL these wires should be Red.....

FROM ignition switch, "switched power" wires are BLACK..... One of these Black wires goes to your "kill switch" and emerges as a Black with white stripe wire which goes to the coil Black/white wire (coil positive)..... The other small gauge coil wire should be BLUE, and goes to the points and condenser.... "Can" of the condenser is grounded to points plate, as is the non moving contact of the points...... When points close, it completes the circuit (The ground-path through engine and frame carrying it back to battery negative)... The coils are now getting current flow and inducing an amplified current in the coil secondary..... When the points re-open, a surge occurs in both coil primary and secondary windings.....The secondary discharges its surge by firing the sparkplugs..... The condenser serves to mediate the primary surge by storing the energy, which it discharges as the points re-close the next time......
 

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Discussion Starter · #3 ·
#1 IF you only have one points assembly, you only need 1 condenser and 1 dual output (two plug wires) coil....
All should allow for the battery voltage, so 12 V battery, 12V rated coil
I attached an image of the breaker and the condenser on the post. Can you tell me if I should add 1 coil and 1 condenser for that.. And please check this image out im confused ?
 

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Sensei
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You can do that, but it isn't necessary, or as efficient (or as inexpensive)....
Your re-charging system is currently (at best) barely sufficient to charge your battery if at all.......
IF you change to running the two separate coils wired in parallel, you will be drawing 57.6 Watts of power instead of the 28.8 Watts the single dual plug coil would require (If I remember the rules for parallel resistance, and Ohms Law correctly).....Your battery would die in a short amount of time......

Whatever you do, you WILL NEED to upgrade the charging system (alternator, rectifier and regulator) to provide adequate recharging current......
 
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