650 to 750 swap

Whoa Nellie! STOP and check the wiring.

three yellow wires hook up to your stator wires. brown wire hooks up to 12VDC switched coming off the ignition switch. black goes to ground (there is probably a connector for it near the rear brake switch) and the white goes to a Y where one leg hooks to the starter solenoid on the lug where the hot cable from the battery connects and the other leg hooks to the fuse box main fuse.

Once you have the wires correct and they probably are not, run the bike up to 4K rpm and check the output of the reg/rec by placing multimeter lead son the battery terminals. You should see 14.5 VDC at 4K rpm.

If the wires aren't hooked up wrong and you get more voltage, the new reg/rec is defective. I woudn't muck around running the bike too much as you will fry ignition components.

Here's the basic concept.


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If it keeps running when you turn off the key, and the lights get brighter, it may be a problem in the kill switch wiring, or your relay wiring. You did disconnect the old ignition wiring before throwing in the relay mod and new wiring, right?

Post edited by: loudhvx, at: 2007/04/16 13:27

Is there anyway the r/r could back feed the coils thru the brown wire? If I put 12vdc to the brown wire ( as a test) with the key off my y/r wire to the relay will be hot. Everything works correctly with the bike not running and the key works when I disconnect the brown from the r/r. I did notice that the 82 750 has a different ignition from the 77 650 could that be it?

Post edited by: zippoman, at: 2007/04/23 22:10

zippoman wrote:

Is there anyway the r/r could back feed the coils thru the brown wire?

Yes, it's possible. But do not run the bike without the brown wire connected unless you also pull off the white wire from the reg/rec.

zippoman wrote:

If I put 12vdc to the brown wire ( as a test) with the key off my y/r wire to the relay will be hot.

This is correct. (with kill switch in the "run" position)

zippoman wrote:

Everything works correctly with the bike not running and the key works when I disconnect the brown from the r/r.

It looks more and more like the reg/rec may have a short in it's detection circuit.

zippoman wrote:

I did notice that the 82 750 has a different ignition from the 77 650 could that be it?

I don't think that should matter much since you replaced the ignition with the Dyna.

I guess I should have said ignition switch, it looks like it has a brown tail by itself off the switch. Can I test for a short in the r/r. Thanks

zippoman wrote:

I guess I should have said ignition switch, it looks like it has a brown tail by itself off the switch. Can I test for a short in the r/r. Thanks

A difference in the ignition switch could be the problem. That's where I would start my troubleshooting.

I just dug out my 750 diagrams.

Are you saying you are using a 750 ignition switch?
If so, the brown wire from the ignition switch is what goes to the brown wire of the reg/rec. It also goes to many other things. The ignition gets its power from the yellow wire coming out of the ignition switch. When the key is off, the brown wire has no connection to the yellow wire. It wouldn't matter if the reg/rec was shorted, in that case. The ignition should shut off when the key is off.

The brown wire and the yellow wire get their power from either of the two white wires going to the switch. The white wires are hot from the main fuse. When the key is off, all wires are unconnected, in the ignition switch.

If you are using the 650 ignition switch, the brown wire feeds the ignition through the kill switch. In that case, then the reg/rec needs to be looked at (along with other wiring possibilities).

Even though it's possible reg/rec is shorted, I wouldn't think it would be likely that the brown connection is internally shorted to the white. A lot of things would have to go wrong (assuming it was wired internally, correctly, in the first place). However, if the ground connection on the reg/rec was not good, it may be possible. Check the ground wire from the reg/rec to the battery to make sure it's not broken. The ground wire to the reg/rec does handle significant current.

To test the reg/rec, disconnect the white and brown wire from the reg/rec. Then run the bike. The white wire on the reg/rec should have 15vDC or higher (possibly much higher). The brown on the reg/rec should have voltage much lower than 15, if any voltage.

Post edited by: loudhvx, at: 2007/04/25 13:13