Fuse burnout on revving

[Arclight88]

Motorcycle has been running fine. Went out this morning, started OK, reved motor to about 5000, then back to idle, reved back to about 3500, and 30-amp fuse blew. Replaced it, started up again, idled for 5 minutes, reved it to about 3000, fuse blew.

Walked away, came back 4-hours later, replaced fuse, started, idled for a few moments, reved it slowly to about 2600, fuse blew.

I wonder if the voltage regulator has gone bad and is allowing to much juice in the circuit as the engine revs.

Has anyone had a similar experience?

 

[Arclight88]

Update: I could not leave it alone. I went out to the garage, put in a new fuse, set the engine run switch to 'run', and turned on the key. The fuse burned out immediately on turning the key. I think this means that I have a short in the ignition circuit (key switch, starter solenoid, or associated wiring).

Any other thoughts would be appreciated.

 

[xschris]

Your main fuse should only be 20amp all others 10amp using higher than recommended could cause damage to parts by sending to much power.

 

[drewpy]

which model?

could be rectifier earthing out. get a multimeter and check out the ohms rating as per manual.
its a process of elimination, slow and laborious.

 

[Arclight88]

which model?

could be rectifier earthing out. get a multimeter and check out the ohms rating as per manual.
its a process of elimination, slow and laborious.

Chris: Thanks for that, I replace with a 20-amp.


Searched on something like 'Fuse blows when I turn key" and found this thread http://www.fixya.com/motorcycles/t2640509-main_fuse_blows_when_ignition_key

Sounds like a hard short between the main fuse and auxiliary fuses. disconnect the positive battery terminal and measure it with an ohm meter (red probe on positive battery lead, black probe on frame)

I tried this with a new fuse, and when I turned the key, resistance dropped from infinity to 0.03 ohms. Fair enough.

So where to start. Whilst I was rebuilding carbs, I also replaced the brushes on the starter motor, which, by the way, makes the start work ever so well. When I reinstalled the starter motor, I noticed that there is barely enough room between the starter motor lead attachment bolt and the engine case. I wondered then if there should not be some kind of insulator between that bolt and the case. I will check there first.

 

[Arclight88]

Chris: Thanks for that, I replace with a 20-amp.


Searched on something like 'Fuse blows when I turn key" and found this thread http://www.fixya.com/motorcycles/t2640509-main_fuse_blows_when_ignition_key

Sounds like a hard short between the main fuse and auxiliary fuses. disconnect the positive battery terminal and measure it with an ohm meter (red probe on positive battery lead, black probe on frame)

I tried this with a new fuse, and when I turned the key, resistance dropped from infinity to 0.03 ohms. Fair enough.

So where to start. Whilst I was rebuilding carbs, I also replaced the brushes on the starter motor, which, by the way, makes the start work ever so well. When I reinstalled the starter motor, I noticed that there is barely enough room between the starter motor lead attachment bolt and the engine case. I wondered then if there should not be some kind of insulator between that bolt and the case. I will check there first.

Well, the insulator on the starter motor connection was intact. I made some adjustments to ease the wiring strain, but this did not fix the problem.

Found another good site on 'how to' troubleshoot electric faults http://w6rec.com/duane/bmw/electrical.htm

Using the Ohmeter method of tracing from the fuse, I found a frayed wire 2 inches back from the Neutral Switch connection that was grounding to the motor. Replaced that segment of wire and she's running again!

Good article.

Thanks, all.

 

[xschris]

Its always the simple things

 

[OleDoc]

Its always the simple things

Aint that the truth