WR450 lighting/charging issues

Long story, happy ending. Not the Asian massage parlor kind of happy ending though, but close.

Note:US WR models only.

I was having a real hard time tracking down why my WR lights were super dim, and why the battery kept going dead. There was only 3 volts going to the taillight, and the headlight would start off pretty bright after a full battery charge but gradually dim. Also, it wouldn't get brighter as the bike revved.

Checked and cleaned all the connectors I could find. Checked all the ground connections. Did all the checks of the reg/rec and AC magneto as per manual. The output voltage of the r/r was only 12.4 or so, actually it was only battery voltage. The AC mag ohmed out fine. Bad r/r, according to the manual.

Got a used one from ebay, hooked it up. No better. Stumped. 2 bad r/r?

Here's the deal. Behind the headlight shroud there is a 6 pin multiplug wrapped in elec tape. Peeled off the tape and pulled the plastic cap off. There is a 6 pin metal jumper to connect all the leads together, and apparently ALL the lighting/charging juice runs through it. The jumper replaces the multi-switch on non-US WRs which control the lights. It is NOT in the schematic.


Cleaned the jumper (a little corroded, gets a lot of water but very little ventilation) and the plug. Used dielectric grease and wrapped it all back up in a double layer of electrician's tape.

Problem solved. The lights are way brighter than I ever remember, and the output from the (original) r/r is bang on spec.

Moral-when the manual's first step for diagnosing elec faults is

'check: couplers and leads connection-rust/dust/looseness/short circuit-repair or replace'

they mean it. Even if it's not depicted in the wiring diagram.

Hope this helps someone, and saves them buying parts unnecessarily.

ps regulator/rectifier for sale. Works fine. Only used for testing purposes...

with mine the tail light gets its power directly from the headlight feed in the headlight plug...that took 3 hours of chasing through the frame...

I know this is a semi old post but I think this is the issue I have been searching for on my bike. I also have a dim headlight and poor to no charging capacity on my 04 450 and always felt it was a poor connection issue but couldn't find the problem. When this problem first arose on my bike last season it was near dark and I popped the headlight off and fooled with the connection a bit and the headlight brightened. I got home that night but the problem came back soon after. It makes sense that my problem would be in this same connection, its 11pm here now but tomorrow evening I'll check this out and post my findings.

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