Okay first of all my bike is a 2000 Honda CBR600F4 with the F4i dash conversion done on it as well as fairing and split seat conversion.

It has:

-new battery
-new rectifier
-new thermosensor (appropriate one from 900RR)

I just had the engine out and replaced the shift shaft, forks, drum, and gears. After putting it all back together while I was bleeding the coolant the rad fan was working perfectly fine it came on and brought back down the temp and turned off all on its own 3 or 4 times. So I figured alright perfect the system is good.

I was in the city the other day and the rad fan failed to turn on at 107 C so I checked the fuse and it was blown (10A) so I put in a 20A, blew that one as soon as I turned the key, same with the 25A and 30A I put in trying afterwards just to see how much amperage was really going through this circuit lol.

So now I'm at a loss I can't figure out why its blowing fuses as soon as I turn the key. I snooped around in the harness right by the battery a bit where the full-size 30A fuse is and found some corrosion on one of those pins but I cleaned it all up and its all good now but its still blowing the fuses as soon as I turn the key.

Any advice would be greatly appreciated.

 

Check the bikes grounds and wiring harness, sounds like something is shorting out. I would start at the fan and work my way back to the battery.

 

^ This.

Let's see pics of the bike too. ;-)

 

Sigh thats what I was figuring... that sucks cuz I inspected the whole harness while I had the engine out and wasn't able to find any rubbed wires or anything wrong with the harness. Guess I'll have to look at as much of it as I can with the engine in now.

Here's a couple pics, thanks guys.

http://www.redline-shift.ca/2000cbr600f4/photo10.JPG
http://www.redline-shift.ca/2000cbr600f4/photo11.JPG

 

A couple of things, never replace a fuse with a higher-rated one.
If a fuse blows, there's a short to ground. Replacing with a larger one will
exagerate the potential damage and/or fire risk. This is not a good thing.

First thing to try, pull the wire's off the thermo-couple to the fan.
If that's where the issue started, see if the short is in the fan/sensor.
If it still blows...then start tracing the entire circuit that the fuse regulates.
Trace the wire from the fuse, inspecting it for frays, warped/melted insulation,
same thing for any connectors you encounter.

Good news is it isn't the 30amp main fuse, you're only tracing a single path.
It's tedious and frustrating, but not really that hard. Just keep plenty of spare
(properly rated) fuses on hand, to check any potential flaws that turn up.

Good luck, Ern

 

I should have explained that too then. When I put the 30A fuse in and turned the key it actually did blow the full-size 30A fuse at the battery connection area which is what made me look in there for corrosion, so I do have to look at more of the harness now correct? sounds like a fun time lol

just for the record too I wouldn't leave a higher rated fuse in there I was just doin it in hopes of finding some more hints or hearing or seeing where the hell the short is going on.

thanks for the advice i'll get to work lol

 

well if it makes your feel better the fan is on its own fuse, so if that's the only one blowing than you can eliminate a lot of the bike right there.