Topic: Neurtal light doesn't come on - CB750 K1 ( no safety unit or clutch switch)

[mycb750k6]

I'm going to start a new thread since I've read every other neutral switch post here and don't have a clue. Most problems relate to the neutral light staying on, dim or some grounding, switch problem.

My problem is my light won't come on. So I've checked the following:
I'm in neutral
The bulb is good.
The green/red wire from the switch under the engine to the bulb is good. Grounding the switch wire to the frame light's up the neutral.
The switch is good -> grounding the switch produced continuity. Removing the switch and the testing continuity by pressing the ball in with a meter checks. I did the same test on a spare K0 neutral switch I had lying around with the same result.
I read about O-ring problems but when I put my O-ring back in the groove and slid the switch in, it went in all the way smoothly.

Now, I've never had this bike or engine running and when I got it the neutral wire that goes to the switch was bolted to the frame along with other ingenious enhancements but I've taken the wiring back to bone stock in every detail. But the point is the PO was fiddling with this problem for some reason. And he now appears to be on some type of hallucinogen so is incoherent and I can't ask him.

Boy I hope this thread doesn't die as I'd like a neutral light. The only thing I haven't checked is the tranny selector mechanism but I have moved it into first and second and back to neutral with ease.

[mystic_1]

Grounding the switch wire to the frame light's up the neutral.

That's good, proves that the wiring and connections upstream from there are good.

Here's what I would do, remove the neutral switch (or use a spare), reattach the wire to it, and ground the switch body to the frame of the bike.  Light should go on.  Press in on the ball of the switch, light should go out.

If that works as expected, peer up into the hole for the neutral switch and make sure you can see the depression on the shift drum, and that it isn't damaged or mucked up in any way.

If that looks good, next test I would do would be to reinstall the switch but not all the way, leave off the mounting clamp and don't push the switch all the way into the hole.  Now shift the bike in and out of neutral while observing the light, any activity?  Experiment with various depths of the switch, at some point you should find a spot where the light behaves normally.  If you do, that means that for whatever reason the switch is "too deep" when fully mounted, so the ball never springs up enough to light up the light.  Why this might be, is a mystery to me.

hth

mystic_1

[mycb750k6]

"Here's what I would do, remove the neutral switch (or use a spare), reattach the wire to it, and ground the switch body to the frame of the bike.  Light should go on.  Press in on the ball of the switch, light should go out."

This is the only thing I didn't try and once it's light out I will.

When I pulled the switch from the K0 carcus, I saw the indent clearly in the switch cavity but didn't check my K1. It's tight down there. What problems am I looking at if I don't see that indent?

"If that works as expected, peer up into the hole for the neutral switch and make sure you can see the depression on the shift drum, and that it isn't damaged or mucked up in any way."

And if I can't or it it appears damaged - game over??

[mystic_1]

Hard for me to come up with a scenario where shift action works properly but the indent is not present.  Could be full of crud I suppose but then I'd expect you to be seeing other problems if that much junk is present.  Really I expect that the drum is fine, just don't know what else to suggest. 

mystic_1

[mycb750k6]

OK I will try your suggestions in a couple of hours. Thanks.

[mycb750k6]

Mystic,
OK so I pulled the switch out and tested as you suggested and both switches tested OK. So I got a mirror and light and looked up the hole and there was no hole for the ball showing so even though  the rear wheel could spin, it wasn't in neutral (I guess ) So I pulled the tranny cover and shifted it until I could see the indentation for the ball up inside the hole. Once I had that, I reinstalled the switch and it worked. And you do have to put the O-ring in first.

As always, thanks for the help!!!!

[mystic_1]

Cool, glad it's working for you now.  Sounds to me like the transmission was in a "false neutral" position, i.e. partially shifted between gears.  Sound right to you?

mystic_1

[mycb750k6]

Yes that's what I think as well. And as much trouble as these sometimes are to get into neutral, I'm not surprised. In reality, it probably would have sorted itself out once I started it. But if I'd waited, I wouldn't have a leaky oil ring to worry about. . Well, if it does leak, I know how to fix it pretty easily. Besides, this one was kinda fun.