Topic: Stator issue

[horrorbiz]

I'm about to start rewiring my bike (1978 CB750K) after most of my wiring harness burned up. Before I start I've been trying to check out what components are okay and what ones need to be replaced or repaired. That said, I'm a noob when it comes to electrical stuff so I'm learning as I go.

I got a multimeter to check things out, my coils and field coil tested with in the right range. On my stator the 3 yellow wires all have continuity however one of them has a very high reading. 1-2 reads about .7, 1-3 or 2-3 reads anywhere from 8 to 20+. I understand that I could be doing something wrong, but everything else I've checked has matched what I'm supposed to get.

My first attempt at finding the problem was removing the shifter cover to see if the wires were okay. They seem fine... My next plan is to take off the stator cover. I took out the outside screws but it's not budging. Do I need to pry it off like I did the starter cover? Or am I missing something? I assume I don't need to under the ones in the center holding the coil?

Any ideas what else I should check in regard to the high reading on that one yellow wire?

Thanks!

[madmtnmotors]

I'm about to start rewiring my bike (1978 CB750K) after most of my wiring harness burned up.

Any ideas what else I should check in regard to the high reading on that one yellow wire?

Thanks!

First:
>Have you resolved the problem that "burned up" most of your harness? How do you "burn up" most of the harness?

Second:
>Use the correct connectors, and splurge for the proper crimp tool. I like Vintage Connections (be sure to get the right size bullet connectors). The connectors from the stator tend to suffer greatly due to the high amp load as well as being exposed to the elements. I usually replace the stator connectors before continuing any troubleshooting, just cut the old ones off as close to the old crimp as possible since there's not a lot of slack in the stator wires. I usually cut the insulator off of the connector first so I can see clearly where I want to cut at the base of the old connector. This only sacrifices about 1/4" of wire. I did a write up about the correct use of the proper crimp tool here:

http://forums.sohc4.net/index.php/topic,148188.msg1688494.html#msg1688494

I also documented some of my work regarding rehabilitation of a stock harness:

http://forums.sohc4.net/index.php/topic,137351.msg1549191.html#msg1549191

Here is a good write up related to charging system diagnosis if you haven't already seen it:

http://forums.sohc4.net/index.php/topic,1012.msg8345.html#msg8345

Third:
>Get the bike wired and running and test the charging system. Static tests of the stator coil are only really good for determining whether the stator has a dead short or not.


All of the links posted here can also be found in my signature below, along with some other potentially helpful links. 

[horrorbiz]

I'm about to start rewiring my bike (1978 CB750K) after most of my wiring harness burned up.

Any ideas what else I should check in regard to the high reading on that one yellow wire?

Thanks!

First:
>Have you resolved the problem that "burned up" most of your harness? How do you "burn up" most of the harness?

Second:
>Use the correct connectors, and splurge for the proper crimp tool. I like Vintage Connections (be sure to get the right size bullet connectors). The connectors from the stator tend to suffer greatly due to the high amp load as well as being exposed to the elements. I usually replace the stator connectors before continuing any troubleshooting, just cut the old ones off as close to the old crimp as possible since there's not a lot of slack in the stator wires. I usually cut the insulator off of the connector first so I can see clearly where I want to cut at the base of the old connector. This only sacrifices about 1/4" of wire. I did a write up about the correct use of the proper crimp tool here:

http://forums.sohc4.net/index.php/topic,148188.msg1688494.html#msg1688494

I also documented some of my work regarding rehabilitation of a stock harness:

http://forums.sohc4.net/index.php/topic,137351.msg1549191.html#msg1549191

Here is a good write up related to charging system diagnosis if you haven't already seen it:

http://forums.sohc4.net/index.php/topic,1012.msg8345.html#msg8345

Third:
>Get the bike wired and running and test the charging system. Static tests of the stator coil are only really good for determining whether the stator has a dead short or not.


All of the links posted here can also be found in my signature below, along with some other potentially helpful links. 

Thanks for all this info! My stock wiring harness had a lot of bad connections and was generally in pretty rough shape. To be honest I wasn't aware enough about it to notice. I was having battery issues and my quick fix was to install a new Reg/Rec combo unit with a new battery. That seemed to solve my problems for a while.

Something caused my Reg/Rec to overheat. (I am sure it could have benefited from a more open air location). The heat from the reg/rec melted the wires around it under the side cover.

I haven't exactly figured out the specific cause, but I imagine it was a combination of things. I'm rewiring the bike from scratch and checking individual components and replacing as needed. I'll be figuring out a better location for the new reg/rec as well.

[horrorbiz]

Update: I removed the yellow wires at the bullet connections behind the shifter cover and checked the wires at the source and they all read normally. So it looks like I'll just need to replace the connecting wires and I'll be good!

[madmtnmotors]

My stock wiring harness had a lot of bad connections and was generally in pretty rough shape. To be honest I wasn't aware enough about it to notice. I was having battery issues and my quick fix was to install a new Reg/Rec combo unit with a new battery. That seemed to solve my problems for a while.

Something caused my Reg/Rec to overheat. (I am sure it could have benefited from a more open air location). The heat from the reg/rec melted the wires around it under the side cover.

I haven't exactly figured out the specific cause, but I imagine it was a combination of things. I'm rewiring the bike from scratch and checking individual components and replacing as needed. I'll be figuring out a better location for the new reg/rec as well.

Update: I removed the yellow wires at the bullet connections behind the shifter cover and checked the wires at the source and they all read normally. So it looks like I'll just need to replace the connecting wires and I'll be good!

Sounds like you are on the right track. The cumulative effects of marginal or corroded electrical connections can eventually add up to excessive heat in various electrical components. The charging system carries the most current and is usually one of the most susceptible.