Shovelhead won't start...electrical?
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3rd Gear
Joined: Mar 2013
Posts: 7
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From: Oregon
Shovelhead won't start...electrical?
To start early 1978 FLH 74ci. point ign.
was running, neg battery post pretty beat up so changed battery.
Now turns over, no start.
getting fuel. plugs are clean and gapped.
no spark, checked resistance at coil (primary and secondary) seems good.
So, next step?
these are my questions that I'm looking for help, please
with ignition on and kill switch on, I should be able to (with multi-meter) check to see if I'm getting 12v to coil?
If not, can I run a wire from baterry pos. to coil and try that? Should the wire come right off battery or be on backside of breaker?
if that works (motor starts), I'll have to trace issue from ign switch, but how will I stop the motor, just pull the wire off the coil?
If I have 12v at coil, then issue down to points?
Hope I'm making sense.....thanks to all who can shed some light.
Ron
was running, neg battery post pretty beat up so changed battery.
Now turns over, no start.
getting fuel. plugs are clean and gapped.
no spark, checked resistance at coil (primary and secondary) seems good.
So, next step?
these are my questions that I'm looking for help, please
with ignition on and kill switch on, I should be able to (with multi-meter) check to see if I'm getting 12v to coil?
If not, can I run a wire from baterry pos. to coil and try that? Should the wire come right off battery or be on backside of breaker?
if that works (motor starts), I'll have to trace issue from ign switch, but how will I stop the motor, just pull the wire off the coil?
If I have 12v at coil, then issue down to points?
Hope I'm making sense.....thanks to all who can shed some light.
Ron
Road Master
Joined: Oct 2012
Posts: 864
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From: Mt. Pleasant SC
Did it run before the Batt change?
Ultimate HDF Member
Joined: Jan 2013
Posts: 5,092
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From: Wenatchee, WA
A coil is composed of a primary and secondary winding. The primary is the fairly coarse winding and it is in the path of the 12volts - ignition points - ground path. You have to have 12 volts across the primary to induce the secondary of the coil. The secondary winding is many (thousands) of very fine windings. When the points close the primary feels the 12volts and a magnetic field radiates out and across the secondary windings, when the points are forced open the field collapses and 20K+ volts are induced in the seconday (magnetic field cutting a conductor), the path to ground is across the spark gap of the plug.
So, remove the plug and ground it. Turn the ignition on and manually open the points - you should get spark, if not either your spark plug is bad or the coil is bad or the primary of the coil is not getting 12volts.
So, remove the plug and ground it. Turn the ignition on and manually open the points - you should get spark, if not either your spark plug is bad or the coil is bad or the primary of the coil is not getting 12volts.
Thread Starter
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3rd Gear
Joined: Mar 2013
Posts: 7
Likes: 0
From: Oregon
Update: She's running.
checked voltage at coil..good.
made sure battery was good and charged.
checked spark at plug..ok but didn't seem that strong.
changed both plug wires....fired right up.
looking at old plug wires, they didn't seem to be seating on plugs that well.
Thanks again to all who posted.
checked voltage at coil..good.
made sure battery was good and charged.
checked spark at plug..ok but didn't seem that strong.
changed both plug wires....fired right up.
looking at old plug wires, they didn't seem to be seating on plugs that well.
Thanks again to all who posted.
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