Hi guys, thought I'd start a thread on this, as my previous one was really more about a flat spot which is now cured. I believe I have a failed reg as it was charging near 18volts at peak rpm. Alternator checked out with exactly 0.5ohms between yellows..As research suggests I should replace it with a unit from a 2002 yamaha R6.

I have dug around and not really found an answer:

The reg that I have now has a black wire going to the rear coil bracket, clearly an earth. Why doesn't the R6 unit?
The bracket my reg was bolted to is insulated from the frame by rubber grommets, so would I need to earth the body of the new R6 reg to the frame?
See pic I made



Any ideas?
Cheers

Hmm, no I wouldn't worry about that. Green wire will be ground enough for it I'd of thought.. I'd try and get the R/R as flat as possible on the bracket though to try and sap some heat from it when running, or it'll fry again - unless it's a MOSFET type.

Your "original" rectifier must not be an original Honda one, mines gone now, but I'm pretty sure it didn't have an extra wire to ground either.

Having had a look at a few wiring diagrams, it appears that the reg/rec with black wire might come from the NC21. However, the black wire in this case appears to go to the starter button and kill switch circuit, emerging as a grey wire that goes to all four coils. If your bike is an NC24, then this black wire would seem superfluous, however the exact nature of it is unclear. I suspect that it is used to isolate the coils on the NC21, but whether or not it is providing a feed or return path is unclear to me.

The R6 unit and those on most other bikes I've ever looked at have been earthed through the negative pin rather than have a separate one for the chassis of the unit.

You guys rock! Thanks that clears it up then, It may have been from a 21, as a few other things seemed 21 ish too, like the main jets and so on. Previous owner must not have known about 400greybike haha.

R6 reg is on its way, but I have a weird short somewhere causing the instrument lights and front indicators to come on when I pull brakes... so am going to clean and check the entire harness before starting her up again... actually need a new battery too come to think of it.

Again thanks you guys are awesome!

Eben007 wrote:You guys rock! Thanks that clears it up then, It may have been from a 21, as a few other things seemed 21 ish too, like the main jets and so on. Previous owner must not have known about 400greybike haha.

R6 reg is on its way, but I have a weird short somewhere causing the instrument lights and front indicators to come on when I pull brakes... so am going to clean and check the entire harness before starting her up again... actually need a new battery too come to think of it.

Again thanks you guys are awesome!

bad earth somewhere..

Neo yes thinking the same thing... its starting to boggle me a bit now. I've stripped bare 80 % of the harness now and still not found anything..

When I plug out either of the brake switches the problem is gone. When I plug out the plug from the clutch side switchgear the problem is gone. When I measure the indicator plugs to earth they all read a short to earth.. but they work fine? It's fkn weird. I shall push on. On the bright side got my R6 reg. But I'm gonna fix this short first as I'm scared it's gonna help fry my brand new reg...

Thanks Neo!

Got the R6 reg wired in soldered on spade females and heat shrunk everything nice and tidy. Also ordered a small LED voltmeter to keep an eye on the battery I still need to buy... pulled through the wires for that so long.

I'm still stumped at this short though. It's as if the park light setting turns on when I pull or step on either brake.
The front indicators come on with the park setting right?

So logic says it's a short between the brake light wires and the park switch wires. But they all check out. The previous owner disconnected the park bulb wires to install some LED lights on the bike, but never got around to it. I cannot find the source of these wires and I'm starting to think they may be taped up together somewhere.

Could anybody with a 24 check for me and let me know where these 2 wires are originating? I stripped back the 3 wires going to the main headlamp bulb but they don't seem to run together...

Thanks all
cheers

There's a wiring diagram for your bike lurking on this forum, it should appear on a search. Should help you...

Hey speedy, found it! seems like as standard there is no park bulb in the headlight... talked to my dad, who is a electronic engineer, and he figures the brake light earth can't handle the current draw and is searching the circuit for the easiest spot to pull earth from, most probably the park lights or the park light switch.

I will try put in a new earth to the rear light cluster and see if it helps, then at least i'll know what line the short is on...
I'll let you guys know thanks
cheers

Sorted... I was really hoping it would be something really complicated because I really like to consider myself not too stupid.

Well turns out I am. And it wasn't.

The previous guy said he redid the wiring. And I can see it now everything's stripped back. All the wires and connections are spotless.

But he did mess up. He put a single element bulb in the brake cluster where there should have been a double. The single pin on the bulb was bridging the 2 pins in the socket. Shorting it.

Man I feel stupid. At least now if anybody has similar issues, my ignorance might save them from ripping a miles worth of tape off their harness.