Topic: My fuses blow...1975 CB550K

[oxidized]

Hi,

Pretty new to SOHC's and motorcycles in general. Just finished a top-end rebuild, everything went together fine. Start it up, sounds good, put in in gear get out of the driveway about 50m and the main 15A fuse blows. Replaced fuse a few times with exact same results. Put in a 20A fuse with same results. Fuse blows right in middle if that matters?

After a search on the forum I tried the "12v light on the fuse clip" method of tracking down a short with no results. Have also tried cleaning all connections in headlight bucket and the electrical connections under the left hand side cover including fuse holder. Electronics on the bike are all stock except for the turn signals.

Admittedly, I'm a noob on wrenching on bikes, but I feel this is problem I should be able to figure out. It's driving me nuts.

Anyways, any input or advice is appreciated as always. Also, if anyone can provide a checklist of stuff I can go through that would be awesome.

Thanks!

[nancy]

Well, this happened to me - I wasn't touching the motor though - I pulled the forks and steering head apart. Fitted new headlamp etc. I got all wiring tested in situ - but when I fired it up and rode down the driveway - it'd blow the 15a. was fine running while still and even as I ran it down the driveway till I started to TURN onto road.
Did this 3 times. Traced it to a faulty earth in the headlamp jungle. I had badly refitted the mass of wires and 1 poorly clamped connector had bare wire showing and was shorting across the mounting nut inside the lamp. I tested this by removing the headlamp lens/front and managed a ride up and down without a fuse blow. Then,..just a matter of patience to check over every conenction in the jungle.
Good luck.

[scottly]

Basically, you are looking for a black wire somewhere, touching a metal part somewhere. You might try turning the handlebars bars back and forth. BTW, the black wire is 12V from the ign sw, and the solid green wire is ground, not like the auto convention where black is ground. Also, that black wire shows up at the kill sw, the oil/neutral lights, the turn-signal switch etc. 

[gravano]

I'm also not very experienced but I had to hunt down some gremlins when my 10A fuse kept blowing. After using the multimeter and finding nothing I realized my headlamp switch (high to low) was loose and every bump I hit was making it go up and down like crazy, blowing the fuse.