Hello all,

I'm pretty new to Harley motorcycles, but have been working on Hondas for a few years, so I decided to grab a 72 Ironhead Sportster a learn a few things. Everything has been pretty straightforward on this bike and I was really surprised by the lack of fragility on most of the parts on the bike.. Anyways I have recently encountered some trouble areas.

Here is what I have run into and my theory on the issue. I would really appreciate any input, feedback or validation of what I'm thinking.

Issue:
Breaker trips after the bike runs awhile (the breaker leading directly from the starter) The breaker will trip every time after the key is turned, until the bike sits awhile

Troubleshooting:
Checked all wires for damaged housing, checked all wiring for proper hookup (the bike was pre-owned and rebuilt) Re-wired the bike COMPLETELY and correctly; Note: some components are excluded, by that I mean most. The bike no longer has any indicator lights, turn signals, or gauges. I also "re-polarized" the generator after altering the electrical system. So currently all wiring is proper and correct as far as the wires being in the right place and in excellent condition.

Thoughts on a solution:
I saw some sparks come from the rear brake light switch, I'm assuming this fella is the culprit BUT since I rewired the bike with less components, originally I thought this would "lighten the load" on any circuit breaker issues.. But can the lack of components reduce resistance resulting in higher voltage? If this is the case maybe all the extra voltage is knocking out the weakest link of the system, which I assume to be that switch...

Allright, what are you guys thinking?

 

I don't think reducing the load will have that effect. You must have a bad switch or maybe a short.

 

Fuses blow when the power shorts to ground. Something is shorting out wire component. Might be a bad spot in the insulation of some wire that takes the heat/vibration to short out