650 to 750 swap

Ive put a 82 750 engine into my 77 650 and got a r/r for for the 750. Seems straight forword but Im blowing my main fuse At 4000 rpm. It seems like when the regulator kicks in it blows the fuse, it will idle all day and be fine. Any ideas? Thanks

Being that your 650 had a seperate regulator and rectifier and the 750's had a combined unit, are you certain that you have all the proper wires connected?

The '77 KZ650 used a YB10L-A2 battery = Capacity (Amp. Hours)11 and a 1.1 amp charging current
The '82 KZ750 used a YB12A-A battery = Capacity (Amp. Hours) 1.2 and a 1.2 charging current.
Along with those minor differences, the positive and negative terminals are on opposite sides also.

The '82 KZ750's also had an IC igniter.
Not that it truely relates to the charging system, but it is an electrical component.
Did you wire that in as well?

It could even be that the 30 year old wiring on your bike simply can't handle the newer charging system, either that or there's possibly a short somewhere.

I used a dyna ignition insteed of a igniter, Im still useing the same battery as before. Its blowing the fuse when it gets to 14vdc, if it is a short wouldnt it blow at other times? btw it wasnt doing this before the swap.

If it actually is a short causing the problem but only at higher rpm's, my guess would be that at higher rpm's/speed, vibration is what is forcing that wire (or wires) to ground out and pop the main fuse.


One thing I can suggest (unless you've already done so), is to swap over to an AGC or ATO (blade) type fuse box and new wiring to it.
The old style glass tube fuses and crappy fuse boxes on these old KZ's are notorious for literally melting.
Good idea to swap over BEFORE this possible happens to your bike too.
Plus the blade type fuses are more readably available than the glass fuses.

Is it a used 750 reg/rec that you put in? Maybe it is defective.

Another possibility is that the connections to the brown wire on the reg/rec are faulty. That would make the regulator stop working... which is not a problem until the engine revs up and there is too much power coming from the alternator.

Another possibility is that the wiring is not correct.
I assume you connected the regulator in where the old rectifier used to be. But you need the brown wire from the old regulator to connect to the new reg/rec (assuming you have a Kawasaki reg/rec). (The old black and green regulator connections will do nothing on a 750-type regulator).

Does your new reg/rec have 5 or 6 wires?

I got the r/r from Jeff @ Z1, its 5 wire to the plug 3 yellow,a brown and a black with a white off the r/r. I have changed my fuses to the blade type and checked all my connections in the harness.

I Think it's something in the wire set up for the three phase charging system the 77's have. It's more than switching some parts. I've changed bottom ends a couple of times and always change out the stators and not mess with the wireing.
Mark

zippoman wrote:

I got the r/r from Jeff @ Z1, its 5 wire to the plug 3 yellow,a brown and a black with a white off the r/r. I have changed my fuses to the blade type and checked all my connections in the harness.

EDIT: It's a 6 wire reg/rec, then.

On the new reg/rec the three yellow wires are the 3-phase ac wires from the alternator and the white and black go to the battery.

The brown wire goes to the brown wire that went to the old regulator.

The green wire that went from the old regulator to the old alternator won't be connected to the 750 motor. The black wire that went to the old regulator is just a ground and you won't need it..

As for the main fuse blowing; main fuses can blow from over-current, or can melt from excess heat due to a bad connection. Follow the advice of replacing the fuse block if the wires look melted or burned around the fuse holders.

The Dyna S uses about twice the power of the original igntion, so it may be using an extra 3 amps. If you are running 3-ohm coils, that's an extra 2.5 amps. This extra current shouldn't be enough to blow a solid 20-amp fuse, but could exacerbate an existing bad connection at the fuse, causing it to melt.

Post edited by: loudhvx, at: 2007/04/14 13:21

ok, so I just take the brown and black straight to the battery, where does the white wire go to? Thanks

zippoman wrote:

ok, so I just take the brown and black straight to the battery, where does the white wire go to? Thanks

For some reason I thought you had a 5-wire reg/rec, but it is actually a 6-wire.
zippoman wrote:

I got the r/r from Jeff @ Z1, its 5 wire to the plug 3 yellow,a brown and a black with a white off the r/r. I have changed my fuses to the blade type and checked all my connections in the harness.

I read that to mean 3 yellow wires, a brown wire, and a black wire with a white stripe.

Since it appears you have a 6-wire reg/rec, the information is different. The white wire would be the positive output wire to the battery, the black wire is the ground, and the brown wire goes to the brown wire that went to the old '77 regulator.

I'll edit the earlier post to avoid confusion.

The brown wire is the sense line for the regulator. Make sure it has the same voltage as the battery's positive post when the ignition is on and when the bike is running. It should be within a half volt or so. If not, then the fuse connections are dirty, or the ignition switch connections are dirty, or the wiring and connectors are bad somewhere. You can fix all that, upgrading the wires a size larger, or you can do the relay-powered ignition-coil mod. That would take some of the load off the main fuse and divert it through the relay instead. The details are on Wiredgeorge's website.

Post edited by: loudhvx, at: 2007/04/14 13:28

Ok. hooked it up and seemed to work till I turned the key off. The bike stayed running and lights got bright, ki;;ed it with the kill switch.I can unplug either the brown or black from the r/r and the key works. Ive done the coil mod so I guess thats why the kill switch works,any Ideas?

zippoman wrote:

Ok. hooked it up and seemed to work till I turned the key off. The bike stayed running and lights got bright, ki;;ed it with the kill switch.I can unplug either the brown or black from the r/r and the key works. Ive done the coil mod so I guess thats why the kill switch works,any Ideas?

Something is definitely wired wrong. The key switch powers the kill switch, so either switch should kill the relay. Don't run it till it's figured out. You can burn the entire system with those conditions (key off and kill switch on).