Topic: Engine Cut-off Switch Malfunction?

[benaneely]

I recently got what I thought was a great old 1972 CB750. It still is a great bike, I just having been riding it because I can't get the engine cut-off switch to work reliably (and haven't had the time to look at it in detail). When I first got the bike, you could move the switch around and eventually could start the engine, sometimes even in the off position. Then it stopped all together. After making sure the battery was fully charged, and shorting the solenoid to the starter to get it started and run for a bit, the switch worked semi-reliably for a bit longer. Again though, after sitting for a period of time, the only way to start the bike is with a screwdriver on the solenoid.

Have any of you ever run into this problem? Is it definitely my R/H switch assembly or could it be somewhere before the solenoid or even with the starter? Thanks for any suggestions, I would love to get back on the bike, and will definitely post a picture soon.

[bryanj]

Go into the headlamp and connect a black wire to the black/white in the loom where the switch connections are.
This will bypass the kill switch to tell you if it is that causing the problem

[Patrick]

If you can start it by jumping the solenoid it doesn't sound like the kill switch to me. When the kill switch is engaged (disengaged?) the plugs don't spark. Jumping the solenoid would not bring the spark back, it would only make the starter turn. That sounds more like a starter button contact issue to me. If it works after wiggling the kill switch, though, that could also be an issue.

If it were my bike I would take the right hand switch apart and clean it. The electrical contacts do become corroded over time. On a K2 the switch is relatively easy to clean.

Patrick

[benaneely]

Will do. I took it apart at the beginning to do just that and was somewhat daunted by the kill switch assembly. Will give it a try and post. Thanks.

[754]

There is another way to start it,
there is a lever above the right footpeg, swing it out and  push it down with your foot, and it will start!!

It is the way mine starts most of the time..

But there is another way, push start it..!!   

[Patrick]

You are, of course, quite right, 754. If he does have an issue with the kill switch, though, he might as well clean off the starter button contact when he's in there. I like my starter.

[754]

I cant even remember what it feels like to Estart a 750..

 bet it has been about 20 years for me...

 never missed it either..




Now in the case of this thread though, if it kickstarts, then the problem may be in an area other than the kill switch..

[benaneely]

I got out to work on the bike yesterday, and figure what happened might help with the troubleshooting. After I got the bike started by shorting the solenoid out, and let the bike warm up, the starter button worked (repeatedly). Additionally, while the engine was running, the engine cut-off switch definitely worked to kill the engine. So what would warming the engine have to do with the starter button working? The bike has been in a garage, and granted it is SC, so its a bit humid, but could moisture really be the issue? Thanks for the hint on kick starting. I am sure once I get the bike tuned up (been sitting too long), that will start it no prob, and I have used it before. Let me know if any of you have any new ideas given the new info.