Bike dies when revved and headlights on

[shnibop]

So, I hate for this to be my first post (been lurking for a long time), but here's my problem:

First off, the bike is a stock 1971 CB450 on which everything worked mechanically and electrical wise.

I decided to try some clubman type bars, so I pulled the switches and controls from the factory bars. Installed the clubmans and controls back onto the bike, started it, let it idle to warm up, gave it a bit of gas at which point the tach/speedo lights lit up crazy bright and went out (not the neutral/turn signal indicator lights however). Later I noticed the taillight (the "low" light, not the bright light that comes on when you apply the brakes) also had burned out. I don't recall if this happened when I had the headlight switched on or not.

At this point the bike would run, idle and rev just fine with and without the headlight on.

After looking through a wiring diagram I determined that the gauge lights and that low brake light were on the same "circuit" (not sure if that's the correct term). Brown/white wires from the tach/speedo go to the light switch as well as the ignition switch (TL1), from the ignition switch (TL2) a brown wire runs to the "low" taillight. So I dug through the wiring and found the Br/W and G wire at the speedo light socket exposed and poorly wrapped up by the previous owner.

I unplugged the tach/speedo lights from the main harness within the headlight bucket, replaced the taillight bulb with a new one and started the bike. Now for some reason, with the light switch OFF, the taillight comes on as soon as the bike is started and will dim and brighten as the engine is revved. I flipped the light switch to the L and H positions and give the throttle a healthy rev and the engine dies almost immediately.

I opened up the start/kill/headlight switch and everything seems in order there, although there was a repair made to the kill switch wires. Headlight switch internals and wiring looked unmolested.

Anyone have any suggestions on what to check next? Could there be an issue with my ignition switch? I'm no expert when it comes to electrical gremlins but I'm not entirely useless. I completely rewired a 1967 Plymouth Valiant from scratch using only a wiring diagram, everything worked fine for years afterwards.

Help...

 

[mydlyfkryzis]

You need to get a Schematic. Somehow, you have connected the unregulated output of the alternator to the lights.

On some years, there is a white a yellow wire that go to the light switch on the right pod. The 2 wires are on the AC side of the alternator and are connected to the charging coils in the alternator. When disconnected, only 4 of the six coils generate.When connected together, all six are used to increase the output.

It sounds like you may of connected these to another part of the electrical system, so your lights are now receiving unregulated AC voltage from the alternator.

You may also have a short to ground on these wires. RECHECK YOUR WIRING CAREFULLY!!! Don't want to burn out any more lights ...

Here's a chematic to give you at least some idea of where the alternator wiring goes...

This is a simplified schematic. On a stock wiring, the white and yellow from the alternator go to the handlebar pod first.

 

[shnibop]

Ok, well I cannot confirm 100% that you are correct at this point, but you are definitely on to something...

When pulling all the wires out of the handle bars, I took note of the fact that all the wires being unplugged from the switch sides matched up to a wire of the same color on the main harness side (except in turns out that not all the wires match up!). When I was plugging everything back in, I had this white/yellow wire that I assumed went to the headlight because I had matched the white wire coming from the headlight switch to the white wire coming from the harness. That was my mistake! How in the hell I overlooked that time and again is beyond me, but as soon as I read your reply to my post, a light went off in my head (no pun intended) and I realized what I had done. At least this all seems to make sense to me, maybe I'm wrong again.

Basically, I had the white wire coming from the alternator going to the low beam wire on the headlight switch, which sent unregulated voltage to the gauge lights (via brown/white wire), as well as the ignition switch (via brown/white wire) which sent that voltage to the taillight (via brown wire), all this occurring at the turn of the ignition switch to the ON position. Which explains why the taillight comes on as soon as the key is turned.

Anyway, I'll give everything a go again tomorrow and report back.

 

[hexinduction]

I know this is old as sin (almost...I guess I sinned before this post) but did OP ever figure out if that was the issue? I have a similar problem, that I swore was a grounding issue, but all my grounds are solid...