EVO wont' fire normally

[panacea]

Mike, on a 1989 flhtc, with Axtell 97" big bore kit,10-1 pistons ,560 cam,S&S cases,S&S reed valve breather,HI-4 ign. custom port and floed heads. When trying to start the engine, she'll turn over fine, but won't fire untill I release the starter button, then just as the button is released she'll catch. have you run into this before? Thanks for your time! Mike

[Mike]

Yep! It's a voltage drop problem at the coil. You can check this with a volt meter on the +side of the coil. If the voltage drops below 7 when cranking the bike will not fire. It needs 9 or more.

Heavier starter cables (Terry products), direct ground from starter motor mounting bolt to battery ground (requires purchase of an additional Terry cable) and a new H-D AGM battery will typically solve the problem.

Another trick is to wire the run switch to kill the coil voltage while cranking but still allow cranking and then switch-on while cranking, after the motor gets kind of a run-on (less voltage drop once turning).