Help diagnosing wiring fault - blowing fuses

Hi all, the 7.5 amp fuse keeps blowing on my Aprilia Mojito 125. This connects to the starter and the CDI - when it blows the engine stops and the starter won't work.

To get it home I risked putting a higher rated fuse in, because bike fires are things that happen to other people, right? (In other words I know that was a stupid thing to do).

Anyway, I got it home ok. But as a result of putting the higher fuse in I've found a wire that has melted a bit - at first I was happy because I thought this might've localised the fault. But the wire is the connector for the brake lever switches - the ones that activate the brake lights, and also close the circuit to allow the starter to work.

Since shorting these wires should only result in the brake light coming on (not the starter as you'd have to press the button too), can anyone suggest why the overheating would've localised there? Does it tell me anything useful?

Thanks all

 

(just to add - the problem is intermittent. I initially replaced the blown fuse with the same rated one and hoped that was job done, but after a few miles it blew again. Whatever short there is, is not "always on")

 

Actually no, shorting the brake light wires will not make the brake light come on.
The wires to the brake light are positive fed, one +feed up to the switch, then you close the switch when you press the brake lever and the circuit continues through the switch to the light.
So if the fuse blows when you operate the brake lever, then that points to a live feed going to earth FROM the switch TO the brake light.

Question: have you had the front panel off recently?

I have known people put the panel screw through the wiring for the brake light switch......

 

Thanks for your input Steve, the fuse doesn't blow when I operate the brake lever. It just happens when a fault in a wire somewhere that I haven't found yet gets jolted a certain way. I meant the brake light would activate if those wires shorted to each other, not to ground.

I have had the front panel off several times recently, including today, trying to diagnose this. I did initially replicate the fault - I put a new 7.5a fuse in, started the bike, moved the mass of plugs/wires with my hand a bit, and the fuse blew.

Haven't been able to make it do it again, sods law. Put another fuse in and went around moving/unplugging individual things to try and isolate the issue, but couldn't make it happen again.

 

Probably a short from the wires rubbing together when the steering is turned I've seen it a thousand times. Never easy to fix. You need to find about where they have been squeezed and then remove the tape stuff, then fix it.
Had it on a gold wing at work once....
Part of the reason I went self employed. No way would I do that job again.