Hello, John Talley here with Partzilla.com.
Today we're going to be looking at the charging system on our 2009 Yamaha YFZ450R.
We had it out at the track this past weekend, and it couldn't maintain battery voltage.
So, let me go grab a couple of tools, pop that seat, and let's figure out what's going
on.
Alright guys, I know we're talking about electrical here but don't break out in a cold sweat.
I'm not even going to rate this barely just a level one, so it's not going to be that
tough.
Let's go over some of the tools you're going to need to pick this apart.
Really short list.
Gonna need just a Phillips screwdriver, a decent ratchet as always, an extension, a
5mm Allen and a 10mm socket.
Only specialty piece of equipment you're going to need?
A volt/ohm meter.
As far as the parts go, if you would, reference our parts diagrams.
That's going to show you where everything is on the machine and more important the correct
part for your machine.
So, once you've got your parts and your tools together, we can jump over there and I can
show you how to get it done.
Alright so let's get that seat popped off.
When we left the track I knew that we were having a problem with the electrical system,
so I went ahead and disconnected the battery.
I don't know what's going on so I didn't want any problems to occur.
So, let me get this connected back up.
The first thing I want to check is to verify that it is indeed not charging.
We're going to do that by just using a voltmeter going across the terminals with it running.
Another reason why I l disconnected it, it is also my theory that there is probably a
current draw that's killing this battery.
But we'll diagnose that after we figure out this charging issue.
Gonna set our voltage to DC volts.
What we're looking for here is something north of twelve and a half volts.
I know that this battery is charged, so it should be good.
So what do we have?
12.66.
So what I want to do next is start it up and let it idle and what we should be getting
is something around 14 volts.
So let's start her up and see what we've got.
So, she's obviously not charging, I mean it immediately dropped to around 12.25 and I
guarantee you that it's gonna keep going down because it's not charging.
So, the next test we want to do is to look at the resistance on the stator.
Now the stator is basically a three-phase motor running backwards.
It's a three phase generator so you've got three different coils in there that produce
the AC voltage.
So, there's a connection right on the side of the-- behind the side of the frame here--
where you're going to see a plug with three wires on it.
That's the one we're after.
Let's see if we can get it wiggled around and unplug it.
I think the only one I have to push in on is right here, and actually push out on it.
There it comes.
Be glad there's an O-ring right there, look at all that mud.
My son and I were actually at Durhamtown last weekend, hence wise a nice color of red from
the Georgia clay.
What we're going to do is take a measurement across each winding, so A, B, and C if you
wanted to name them.
What we're looking for as a resistance measurement somewhere between .32 and .48 ohms, so it's
not a big measurement.
I don't love this test, but at least it gives you an idea if there's a complete short or
if there's a complete open.
Either one of those we don't want.
So, let's go from here to here.
Alright, .6.
A little on the high side but I can believe it. .5, .6.
.6 So I'm betting the actual stator is in good shape.
Alright, like I said I'm not a huge fan of doing just a resistance check because it's
really not that accurate.
What I like to do is actually take your meter, put it over to AC, and we'll do a measurement
directly across as we did before with the resistance but measuring AC voltage, which
should be in the 35-40 volt range, somewhere in that neighborhood.
Alright, so that verifies it.
Our stator is in good shape, so what I want to do next is pull this front panel and take
a look at the regulator rectifier and see what's going on with it.
Alright, basically what you have here is five wires coming into it.
The ones at the top, there's one red and there's one black.
That's the charging circuit that should be going back to the battery.
So, I want to unplug it and make sure that I see 12 volts.
The other three are actually the ones that are going down to the stator.
So, we're at DC voltage, and we should see the 12.5-ish measurement.
12.7, so that is it.
Alright guys, we've done all the tests that I would normally do.
According to the Yamaha manual, they usually don't recommend the diode test, which I've
done to this one and they look okay but guess what?
It's still not charging.
So what Yamaha says to do is just go ahead and replace it.
So guess what?
That's what we're going to try next.
I usually hate throwing parts at something, but this is what they are telling me to do.
So, I've got the volt/ohm meter hooked up, let's see what happens.
Flip her on, run position, start her up.
Well, lookie there.
Charging right at 13.9 volts and that's what we were looking for.
Turns out Yamaha knew what they were doing after all, huh?
So, let's get this thing put back together.
We can go ahead and leave that plugged in, I'm just gonna move it up and out of the way
to the side a little bit.
There's only a couple of 10mm bolts holding it in, and then she's going to drop right
out of there.
It still really surprised me that the diodes actually tested on this and yet it does not
work.
First time I've run up on that.
That might not be such a good test after all, you know?
Because most of the time those diodes are either open or shorted to ground and that
was not the case on this one.
Alright, let's go ahead and get our front plastic back on.
Probably doing this a little backwards but it'll be okay.
Well alright guys, that wraps this one up.
Well listen, if you need any of the parts for your machine, why don't you come see us
at Partzilla.com and we can get you taken care of.
If you have any questions or comments, leave them in the section below and I'll do my best
to answer them.
Til next time we just wanted to say thanks for shopping with us here at Partzilla and
we will see you in the next video.
have a great day.