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Very weak spark?


SlowMoe

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Can't get her to crank, there is a spark but it is very weak.

The last time I rode it, it ran fine, a couple times it acted like it wanted to die for a few seconds then went back to normal. Saved up for a couple weeks, and now nothing but a very weak spark in both sides.

 

Coil?

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  • 2 weeks later...

First off, the Banshee has pretty weak spark in general.  The pickup gap affects only timing and pickup intensity to trip the triggers in the CDI.  It will not affect spark energy.  As well, rust on the flywheel will generally not affect spark energy.  The magnets in the flywheel are what generate inductive energy through the ignition coil.  If the magnets are damaged, that will affect voltage output. 

 

The easiest way to troubleshoot these issues is with an oscilloscope.  You would be looking for AC voltage from the ignition coil around 50-100V and approx 1V from the pickup coil.  The wave frequency is dependent on RPM so most basic meters will not detect it accurately as they are tuned for 60hz AC. 

 

Once you have that established, you can examine the wave forms on the primary side of the coil which will again be around 50-100V.  DO NOT connect any meter to the secondary or you will fry it. 

 

The secondary should be checked with a ohm meter.  Common issues are plug caps, and wire lead terminations. 

 

Another common issue is the use of resistor plugs WITH the resistor plug caps.  These two resistors will work to reduce spark energy so use a non-resistor plug if you use factory spec resistor caps. 

 

 

Brandon

Mull Engineering

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I really have had issues with dirty flywheel and excessive pickup gap effecting spark but maybe in theory it shouldnt but real life... it does and will either foul plugs or not rev like it should. Just my experience fwiw

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