Topic: Headlight Draws Current When Off

[750man]

I have a 1975 CB750 K5. When I run it with the headlight fuse in but the headlights off it takes a while for the bike to start and warm up when driving. If I take the headlight fuse out it starts perfectly and runs more smoothly. I really like the better performance without the headlight fuse but there are times when I need the headlight. How can I fix this? Is the possibly a short somewhere?

[750man]

Any ideas on how I can fix this?

[grumburg]

Had a similar problem with my 550 last year. When I took it apart, the wiring harness was held together with duct tape and wire nuts. (70s ape hanger installation and apparently bad drugs). Got everything repaired and worked great. Would sit and idle and when you rode 50 feet would burn out the fuse. Removed headlight (twice) , replaced fuse, checked everything. Fuse box was hot. Turned out when I pushed headlight back in, had a connector with about 1/8th inch of bare wire that would touch the back on headlight and short out.

[csendker]

I had a problem with my fuse block.  It ended up being:

1) dirty/corroded fuse contacts
2) an auto fuse (1-1/4" which is too long) jammed in, decreasing the contact surface area, which heated up the fuse ends

I cleaned everything up to be nice & shiney and replaced the fuses with the proper 1" long ones.  Problem solved for me. 

Additionally, I bought some real replacement bullet connectors for any existing connectors that the PO had hacked up.

I also had a crappy negative wire.  I replaced this with a new one and cleaned up the negative wire ground connection.  You may want to make sure the ground is good & clean even if your wire is OK.  A poor ground will be the cause of many headaches.

You can check for a short by looking for a trickle amp draw between the negative post of your battery and the ground on your frame.  When everything is 'OFF', there should be no current flowing.  If you find a trickle, then you likely have a short somewhere.