The Italian

The Italian

2006 MV Agusta Brutale 910
2006 MV Agusta Brutale 910

First Problem

Recently a buddy of mine picked up a new bike; well new to him. A 2006 MV Agusta Brutale 910. Such a beautiful machine! One of the best looking single-sided swing-arms put on any bike. Sharp angles contrasted by soft curves, tubular trellis frame, and gigantic forks give this bike a look unlike any other I have come across.

Like any Italian, she is a bit temperamental. Ran great for a couple days but then she refused to start. I was not there to try & help out but with a car attached to a brand new battery she finally came back to life.
"Brand new battery & jumped to a car? Does it start if you jump the starter relay? Ok cool... Sounds like the relay is on the way out. I probably have one lying around the garage that will fit."

Turns out that I had a couple of Yamaha relays that looked identical to the one on the MV.  I ran a couple tests with my multi-meter & verified that the relay was the culprit, handed him the spares and we parted ways.  He changed out the part and all seemed good... or was it?

The next day he made it maybe 10 miles down the road before the bike died. Now there was a charging problem! WTF?! We got the bike to my garage to run some tests and why not do some routine maintenance while we were in there? This bike has an alternator?!
In my garage awaiting tests.
In my garage awaiting surgery.

The Revelation

Ok now I am used to permanent magnet charging systems with separate stator and regulator rectifier units.  On an alternator the entire unit needs to be removed to test even the diode pack, and boy is it tight in there. The starter needs to be removed just to be able to get the alternator out. At least the motor did not need to be dropped to get it, which is what it looked like. Before we remove this thing let's do some tests. The main power lead did not have voltage but my experience with alternators is only hypothetical and the terminal reads a good contact to ground. "Let me check out the wiring diagram during the week and we can get back to it next weekend." This wire should have better voltage... so why is it connected to ground?

The following weekend came and we started testing again.  Grounded with no power.
"Tell me again what happened? So it was charging fine until the starter solenoid was changed? Ok. Do you have the old one with you? They look and test the same... except for this!" 
The solenoid also contains a built in fuse that is the main fuse on most Japanese bikes and gets its power from one side of the starter motor circuit.  The Yamaha part pulls power from the opposite pole then the than the MV! Swap the two wires on the starting circuit and voila! We have power! Sooo simple. Yet I overlooked it. I must be a bit out of practice as I don't get to play with electronics that often these days.

KISS it: Keep It Simple Stupid.
The MV Agusta Brutale is fixed and ready to ride!
Fixed and ready to ride!
This post contains affiliate links. :)