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Jeff Policky
Jeff Policky, Motorcycle Mechanic
Category: Motorcycle
Satisfied Customers: 2425
Experience:  Yamaha Gold, Suzuki Gold, Honda Bronze, Polaris Bronze, BRP
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I have a Yamaha 1980 Dt 125 , CDI System no points. One day

Customer Question

I have a Yamaha 1980 Dt 125 , CDI System no points. One day it quit running , I have ck carb, cleand carb, the compression is good , only thing I have discovered is a very low spark , I replaced the main coil , not change ! wont even hardly light up a tester. I have checked all kill switches and kickstand switches all ok .
What unit controls the higher spark , CDI or the lighting coil ?, voltage reg. or rectifier ?
Thank You , Joe Briggs
Submitted: 1 year ago.
Category: Motorcycle
Expert:  Wayne S. replied 1 year ago.
Hi, your spark starts with the CDI unit getting charged by thecoil in the stator or magneto area. Once the CDI is chargedthere is a pulser or pick up coil also near the stator coilthat triggers the CDI to release the voltage to the ignition coiland spark plug. The problem could be any of those componentsor something simple like a spark plug cap or plug.I can try to get some specs for the coils which you can checkwith an multimeter set on ohms.If your bike has a battery it might be using that for powerif it has electric start. Otherwise the magneto flywheelmagnets work on the coils to provide voltage to the CDIEven a rusty flywheel can affect the voltage to the CDI unit.Be back in a few minutes.--
Expert:  Wayne S. replied 1 year ago.
Hi, did you get the bike working?
Customer: replied 1 year ago.
Hello , I discovered the kill switch was shorting out. I read a blog somewhere to ck that out. I also re soldered some wires that were very brittle . The main hot wire from main coil was very brittle att. to a resistor type small fuse box near the battery. But the prob. was the kill switch.
Would not even think of that as it worked like it was new .. ??
Thanks, ***** *****
Expert:  Wayne S. replied 1 year ago.
Glad you found the problem.
Good luck!

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