I had the same problem for awhile when I still had the stock engine.
Does your neutral light work? If your neutral light works then your neutral switch should work, but you did mention that the solenoid only jumped after you bypassed it.
The click is the starter relay working. The slight hum is the electric starter trying to work. It is possibly just stuck from years of non use and needs a little push.
I solved my problem of this by attaching a 12v charger to the system (sounds really dumb I know, but I didn't know this until after-the-fact). I put the negative lead on ground (such as where the battery negative connects to the frame) and the positive lead on the positive battery terminal. This was purely accidental as I was trying to see if having a full 6v 6A hooked up to the battery would cause the starter to finally work (assuming that my battery wasn't fully charged up enough to power it). I had left the charger on the 12v 2amp setting from charging a 12v battery before. The electric starter worked flawlessly and the engine fired right up!
This gave the system a nice jolt and the starter had plenty of power to free itself up. My lights didn't burn out and were brighter than ever. I didn't try revving the engine.
I have spliced my headlight to be protected by the fuse wire. Well sort of. My setup is a bit different than what you're asking about.
I did it with a Lifan 140 installed - the rectifier is 4 wire instead of 2 wire. I put the yellow engine wire directly into the rectifier (the 4 wire rectifier of the clone engines has an input for the yellow wire - which is supposed to just "T" into the original yellow wire configuration) and the yellow wire of the original wire harness was spliced into the black wire of the key switch. That way whenever I turn on the power, the headlight turns on and is now running on D/C rather than A/C. It is also protected by the fuse now. Don't know how that would be done with the stock 2 wire rectifier, where would the yellow engine wire go?
I'm sure you could splice a fuse into the yellow wire somewhere. That yellow wire goes directly to your left handlebar switch and in turn to the headlight.
Try Ebay for other parts. There are usually people parting out bikes like ours and parts are plentiful. All parts except for a leg shield... I bought the one from DrATV and well, it still has that "in box" bend a bit, which bothers me.
Also cmsnl.com stocks lots of new OEM parts. You could try there as well, but they are located in the Netherlands and can be a bit expensive. http://www.cmsnl.com/honda-c70-passport-1981-usa_model7432/partslist/
www.tenavintage.com has lots of cheap parts also. I think he's a one-man operation in Indonesia, so it might take some time for shipping. But good news, his site offers free shipping and the prices are very good.
Sorry if that seemed a bit confusing. Good luck!
--- In Honda-C70@yahoogroups.com, "j.thewildman" <j.thewildman@...> wrote:
> Howdy everyone. I am new to the group and joined as a recommendation from my friend Tim. I am a long time motorcycle rider and just became the owner of a 1981 Passport. I've been keeping up on the threads and have been doing a little research but wondered about some help if at all possible.
> My problem:
> Electric ignition does not work. My research has brought me to the conclusion that, number one, I have a bad Neutral Safety switch, number 2, the starter solenoid "could" be defective, and number 3, I can't get the starter to turn over. I have tried to bypass the safety switch, (this is how I determined it to be bad), after bypassing the safety switch I could jump the solenoid and could hear a click and some humming. Any suggestions?
> I am also wondering if anybody has spliced a fuse to their headlight to avoid the dreaded "dead battery spike" that kills the headlight? Thoughts, ideas?
> Also, I have already purchased several items from Beatrice Cycle but they didn't have everything I needed. ie. the Neutral Safety switch. I am also looking for a leg shield and some shocks. Any suggestions?
> Thanks for your time,
1970-73 C70 Honda Service Manual: http://tinyurl.com/6ebwtw
1970-73 C70 Troubleshooting Guide:
http://tinyurl.com/6ebwtw (scroll to sec.7.1 page 101.jpg)
1980-83 C70 Honda Service Manual: http://tinyurl.com/hu42c
1980-81 C70 Troubleshooting Guide:
http://tinyurl.com/hu42c (scroll to sec.18-1 page 170.jpg)
1982-83 C70 Troubleshooting Guide:
http://tinyurl.com/hu42c (scroll to sec. 20-28 page 205.jpg)
1980-81 C70 Maintenance Schedule: http://tinyurl.com/z4zn6
1982-83 C70 Maintenance Schedule: http://tinyurl.com/hw35c
More resources for C70 Passports and Cubs: