An Electrical Problem


I posted this just before the migration to the new site. It appears to have been lost in the changeover (which I was warned would probably happen) I am reposting. Hope thats OK.

The Bike: A 2004 WR450F which has an aftermarket Acerbis headlight unit on it. This was on the bike when I bought it and it has two 35 watt household type halogen bulbs in it. The type you can buy at any Home Depot for your overhead light fixtures. I rode the bike like this for two years and never had a problem with the lights.

The Problem: Early last season I started to blow headlights. I replaced them and then discovered during the next ride that they were blown again. I replaced them again and started the bike and tried to figure things out before I went on the trail.

They would brighten as I revved the bike and then dim on throttle back....they have always behaved like this and would normally reach a point of max brightness and all would be well. I kept revving the bike this time I noticed that they kept getting brighter and brighter until they blew...the same thing would happen to my tail light. Apart from this the bike would run exactly as it always did...very well. I finished the season riding with no lights...the police where I ride thankfully cut off road vehicles a lot of slack...I have to ride on the highway to get to the trails.

So my quest for information is in two parts.

Question #1 -My thinking is that my regulator/rectifier is toast. Does this make sense? Do they just stop working properly? Can anyone think of another reason for the problem??

Going on the assumption that it was a regulator/rectifier issue I traced the wiring harness for it, and it disappers completely between the rads and almost appears to go right into the middle of the frame upright (where the oil dipstick is). It disappears so completely that I am unable to see the two multipin connectors that I understand are on the end of the harness and that snap into the main harness I presume. I have looked at a new reulator unit (I was told it was for a 2004), and the harness is only about 20 inches long..which corresponds exactly to where it gets buried in the rats nest of wiring/cabeling between the rads.

SO....Question #2...does the harness in fact end at this location with two multipins and they are just out of sight?? and is it necessary to pull the rads off in order to hook up a new one?

I am trying to avoid pursuing the wrong solution to the problem and also avoid pulling the rads if I don't have to.

Thanks guys for any and all assistance...much appreciated.

Well, that's too bad nobody replied to this. I have the exact same problem with my 2006 which is the same bike. Front and rear light will go brighter and brighter as i rev the bike up. Then, they will blow.

-On top of that, i noticed couple of weeks ago that my batterie was always low. My starter would not work due to low amps. I recharged the batterie twice already but then is only good for couple of hours.

-When i put the multimeter on the batterie, ''with the bike running idle'', i only get 8 to 9 volts. When the bike is rev up, the voltage does not go to 12 volt (like its supposed too).

-When coupled with my truck with booster cable, the starter works as advertise and all my lights, flashers, odometer, horn works too.

So, now hopefully someone will help or say something, i would thing that there is something wrong with either the Magneto or the voltage regulator / rectifier.

Is there a way to find which one is at fault ????

I'd start at the voltage regulator (replace with same unit which is currently installed either aftermarket or oem). Re start the bike then check voltage at the battery.

Generally when this condition exist, it'll also take out (cook) the battery so be expected to have to replace that too.

If that still doesn't solve the issue, then you'll be looking at a stator replacement.

Thats what i wanna do but i dont know anybody here with a WR 450. I dont wanna buy one for nothing. Are you AVS tech RS25 ??

Check your manual for how to test this but I'm sure it's the regulator and I'd replace the battery as well. They don't like over-voltage for too long.

Microfiche may show the location better as to how to get at it.


Thats what i wanna do but i dont know anybody here with a WR 450. I dont wanna buy one for nothing. Are you AVS tech RS25 ??

Nope, AVN in charge of 1AMS Engine Bay test facility. Send me your address and I'll see about sending you out a good oem voltage regulator. If it fixes the issue, then we'll work out a price for the unit. I've got 2, one that came with my bike, and another which has 1hr worth of riding. In my situation, it was the stator which was bad.. not the volt regulator.

Is your electrical system stock? or is there a Tusk/BajaDesigns dual sport kit on it?

EDIT: Reading fail... I see you mention having horn etc... so I'll run a really good assumption that you're in fact running a dual sport kit, which would also indicate that you'll need to replace your voltage regulator with the matching one from the kit. Chances are, the your stator was modified (floating ground), so you'll need to do a aftermarket unit. On your bike the volt regulator is located on the LH side of the frame near the steering tube and it should be painfully obvious if it's OEM or not.

Edited by rs25
Well, that's too bad nobody replied to this. I have the exact same problem with my 2006 which is the same bike. Front and rear light will go brighter and brighter as i rev the bike up. Then, they will blow.

Actually the perceived lack of reply may be a further holdover from my originally posting this during the software changeover...because the problem was solved.

To up date things...I changed my regulator/rectifier..(.easy job..but you will have to pull at least one rad)

and all my problems disappeared. sure sounds like you have the same problem I did. Once I put in the new reg/rect it also started better. You may find your other annoying electrical issues will be resolved when you make the change.

I see your in Ontario like should be able to order the part from the US for about $35-40 less than getting it from an Omtario dealer...worth it if you can get a decent shipping arrangement.

Right on travertt,

I will try with the new Rectifier / regulator and see from there. I hope thats the problem.

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