Author Topic: 1973 CB500 Neutral Light (Read 1950 times)

Nomad · « **on:** February 17, 2019, 09:10:17 AM »

I'm new to the forum and recently purchased a 1973 CB500 Four. The two prior owners were not able to get the bike running, but fortunately in 2 days time I found the issues and the bike runs great. The only issue I am having is the neutral light in not lighting up. The bike starts fine, so I checked the bulb and it is fine, then traced the wiring to the neutral switch and the ground which appear fine. I removed the neutral switch and it is clean where the green/red wire connects. I searched this forum and found a prior thread with this exact issue, and the solution was cleaning the wiring connection points, but that is not the solution in my case. I've read if the neutral switch itself is bad, the bike will not start but don't know if that is true however my bike starts fine. I've tried to locate a photo of a 1973 CB500 neutral switch online, but haven't found one yet. The other version of switches I have seen have a gold point sticking out at the bottom and mine does not. I've included a photo of my neutral switch. Any thoughts or suggestions are greatly appreciated!

Deltarider · « **Reply #1 on:** February 17, 2019, 09:33:01 AM »

That's not the neutral indicator switch, I'm afraid. It's the oil pressure switch.

bryanj · « **Reply #2 on:** February 17, 2019, 09:33:09 AM »

That is the oil pressure switch NOT the neutral switch! Neutral switch consists of two parts, a a static switch bolted to the crankase in front of the oil pump and a rotating part attached to the end of the selector drum by a crosspoint screw. Either or both parts can go bad. I have some NOS ones BUT they are not cheap and in UK.

Nomad · « **Reply #3 on:** February 17, 2019, 09:49:32 AM »

I told you I was new to this! I will track down the correct switch and post what I find out.

Deltarider · « **Reply #4 on:** February 17, 2019, 10:00:05 AM »

Lightgreen/red wire (LG/R) goes to the neutral switch and blue/red (B/R) goes to the oil pressure switch. Your model CB500 did not have an arrangement to prevent starting when in gear.

Nomad · « **Reply #5 on:** February 17, 2019, 10:55:43 AM »

I found where the switch connects and cleaned the connecting points and have continuity. I did not pull the switch out yet (didn't see an easy way to remove it). What position should the bent gold arm be in? Does the black round piece with the screw in the middle rotate and make contact with the bent gold arm?

bryanj · « **Reply #6 on:** February 17, 2019, 01:47:16 PM »

To put it in Queens english that static part is bent to buggery! The retaining screw for the static part is the crosspoint just below the wire, the copper "tang" is not supposed to have a hole in it but a raised dimple and it is supposed to bend back towards the crankcasr and connect with the brass strip on the rotating part which has a "tang" on the back that fits in a groove in the steel shaft, this frequentlu breaks off meaning the copper contact is not in the correct place.

Hope all that makes sense, like i said i have NOS of both parts if you want to pm me for a price

Nomad · « **Reply #7 on:** February 17, 2019, 02:24:40 PM »

Thank you for this information. So it looks as though I need the part pictured below. I think I would like to start with that rather than purchasing both parts of the switch.

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Nomad · « **Reply #8 on:** February 17, 2019, 03:45:02 PM »

I bent and positioned the copper arm where it is now making contact when the bike shifts in neutral and the light is coming on. I may try it this way and see how long it lasts.

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Nomad · « **Reply #9 on:** March 13, 2019, 09:13:35 AM »

Neutral light is still working with the modification I made.

Edub · « **Reply #10 on:** December 29, 2022, 11:32:03 PM »

I know this is a really old post but I'm looking for info on this topic? Are you still around? I'm trying to get my 1973 CB500K2 neutral light to work more reliably. I don't even know how to access the switch.

bryanj · « **Reply #11 on:** December 30, 2022, 12:00:46 AM »

Remove the sprocket cover, the one the clutch cable goes into and its in there under all the accumulated grease and crap

dave500 · « **Reply #12 on:** December 30, 2022, 03:17:11 PM »

the little plastic rotating switch has a little index key inside that aligns on the shift drum,it can be easily broken when removing or replacing it,its pretty brittle take care with it.

bryanj · « **Reply #13 on:** December 31, 2022, 12:23:11 AM »

I no longer have any of the static switches available but a uk member has had just the contact part made, needs shaping and attaching of course.
I do have a very limited number of the rotor part BUT i am in UK so shipping is a big part

newday777 · « **Reply #14 on:** December 31, 2022, 03:05:07 AM »

Quote from: Edub on December 29, 2022, 11:32:03 PM

I know this is a really old post but I'm looking for info on this topic? Are you still around? I'm trying to get my 1973 CB500K2 neutral light to work more reliably. I don't even know how to access the switch.

Welcome aboard Edub
Be sure to post back a reply of your findings and the fix you end up with.
Also go to the new members section and introduce yourself and your bike. Pictures are always good.

Edub · « **Reply #15 on:** January 06, 2023, 10:13:11 PM »

Newday, Bryanj, Dave,

thanks for the responses. I think what you're saying is it's under the left side crank case cover. Can I take that off easily and not expect some spring or gasket or something to get screwed up? I mean, is taking that off, cleaning it and putting it back, a couple hour job that I can do and drive the bike the next day? or am I likely to screw something up and need to buy a new part before I can ride the bike again?

I'm pretty handy, I've rebuilt the carbs, installed a center stand, set valves, etc.

dave500 · « **Reply #16 on:** January 07, 2023, 12:17:09 AM »

yeah that left cover comes off easy no nasty surprises,only thing is youll have to back off the clutch cable on the 500s,then re adjust it on assembly,no biggie,kill two birds and get all the years of crap build up from behind it at the same time.

bryanj · « **Reply #17 on:** January 07, 2023, 12:34:23 AM »

Only thing you might find is the clutch pushrod broken which can happen if the chain is loose.
Also there is a ball bearing inside the clutch adjuster mechanism which can fall out.
There is no gasket and shouldnt be any oil but normally loads of old dry grease and sh!te to clean out.
Sometimes the footrest has been bent a bit and needs loosening to remove cover but if all is as original shouldnt.
Replace switch when ll crews undo nd you hve new parts is less than 1 hour, faff about trying to make old bent switch work when screws are tight and awkward needing impact driver up to 5 hours

dave500 · « **Reply #18 on:** January 07, 2023, 12:44:43 AM »

you make it sound hard,itll be done slowly in coupla hours.

bryanj · « **Reply #19 on:** January 07, 2023, 03:40:53 AM »

Dave, i can do them in 15 minseven if they need "adjusting" but the poster does not sound too mechanicaly/electricaly minded so just being realistic

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Author Topic: 1973 CB500 Neutral Light (Read 1950 times)