Topic: 70 mph highway breakdown. Starting places?

[sammermpc]

Cruising down I-95 just north of Providence, RI -- CB500 ('72) engine cuts out entirely. Wasn't changing lanes; nothing. Pulled over pretty quickly: no lights, no electric whatsoever. No horn, starter, etc. Checked the fuse. Looks OK. Changed it anyhow. Still nothing.

So now my bike is sitting in a yard someplace north of Providence and I'm scratching my head. The bike had been running smoothly at high RPMs all weekend. I think the battery is OK -- I saw some sparks will fiddling with the fuse wires. Not sure why -- could be part of problem?

My only thought, is that I was pushing down on the headlight the night prior to adjust the beam, and something worked loose up there, but I don't know enough about the electrics to know what would cause a blackout like that.

Any thoughts on getting started on debugging? Could something serious have blown-out?

[Black 750K8]

If you have a way to check first see if you have battery power 12.6 volts.

[sammermpc]

I'll call the yard tomorrow -- they said they have a guy who does bikes, and have him look. I'd expect to have seen some dim light on the signals or the headlight at a lower voltage. No oil light, neutral light, etc. Just a brick. I'll definitely head back with a multimeter. What're the odds that this is something simple (loose wire), vs. something more serious (I don't even know). I should probably just find a truck and haul it back up to Boston.

[Black 750K8]

It could be just the main battery wire came loose hot or the ground. You have lost main power it will be simple I think. start at the batt. and work your way to the fuse I would suspect a ground.

[seanbarney41]

I'd be checking the key switch out pretty thoroughly

[Black 750K8]

I'd be checking the key switch out pretty thoroughly

Good point

[iron_worker]

If you saw sparks while fiddling with your fuse box wires then start there. Sounds like maybe a solder joint broke on the back of the fuse box. That happened on my bike except it was a brand new (reproduction ... ) fuse box so I had to trace it down. I also saw sparks when I jiggled wires down there which also blew my main fuse at the same time so make sure you have a spare.

IW

[HondaMan]

If you suspect the key, PM me for hotwire instructions that you can do on site to test it. 

Otherwise: check the fuse clip carefully: they are usually in poor shape today. They had a gold-colored Chromate coating years ago, which now has become dark brown and conducts poorly, if at all, at the fuse clips. It then acts like someone snatched the fuse out of it, when it gets hot enough. When it cools down again, it might work somewhat (dim lights, but spark works somewhat). Scrape the fuse clips shiny clean for a short-term fix to get it home.

[sammermpc]

Hmm...the fuse contacts are definitely looking pretty tired. The key switch is where -- where the key actually turns? I'll give that a look. Summarizing:

1) Check out key switch
2) Traceback hot and ground from the battery
3) Brush fuse clip contacts (they corrode)
4) Check solder joints on fuse box

I'll pass this on to the guy on the yard -- I want to save myself a trip back down there, if I have to get it towed back here anyhow. Maybe he can do a quick once-over of the electrical.

[HondaMan]

Hmm...the fuse contacts are definitely looking pretty tired. The key switch is where -- where the key actually turns? I'll give that a look. Summarizing:

1) Check out key switch
2) Traceback hot and ground from the battery
3) Brush fuse clip contacts (they corrode)
4) Check solder joints on fuse box

I'll pass this on to the guy on the yard -- I want to save myself a trip back down there, if I have to get it towed back here anyhow. Maybe he can do a quick once-over of the electrical.

The CB500-4 has only a single fuse: the fuseholders were often replaced with crummy(er) ones by unknowing owners. The replacement versions were often the open-clips-in-nylon-clamshell variety, which fare poorly at 15 amp peak current loads. A modern automotive blade-style fuseholder (get one with YELLOW wires, heavy duty) will go a long way toward improving the reliability long term.

[dave500]

this is a simple blade fuse mod,some of the holders you buy are awkward to insert and remove the fuse.

[PeWe]

Try this interactive circuit diagram that will make things easier to understand.
http://oldmanhonda.com/MC/wiring500.html

I have had similar for many years ago in my CB750. Short circuit in the wires from the handle bar controls, wire-handlebar. Main fuse blew.

[bjatwood]

this is a simple blade fuse mod,some of the holders you buy are awkward to insert and remove the fuse.

Pretty nifty idea right there Dave!

[HondaMan]

this is a simple blade fuse mod,some of the holders you buy are awkward to insert and remove the fuse.

Dave: That's actually an EXCELLENT idea on the early bikes with one fuse!

I have recently bought 3 of the "professional" fuseholders for a single blade fuse, only to discover that all 3 of them twist their contacts sideways in their holders and cause only one edge of the blades to make contact. The fuses get so hot that they then melt the plastic holders, and eventually the fuse. I had bought them for their little waterproof cap covers, but I have done the same thing you did just now on my own bike to solve it.

Good job!

[sammermpc]

Great, thanks for all the advice!

So, an update -- so I called the yard today and didn't get ahold of the right person. They called me back today, saying that it was 'all good' and that there was a problem with the 'wire switch' that someone had fixed. The person on the phone wasn't the mechanic, who'd left, and I couldn't get any more details.

I'm damn curious to know what they did, though, because she said the bill is $175.00. I hope nothing crazy. Then again, I hope I'm not being charged almost $200 for loose wire that I would've found in a minute. We'll see this weekend when I have time to get down there and pick it up.

[Jerry Rxman Griffin aka MuthaF'er]

This is why you work on your own bike or find a friend to help you.

[Nic]

This is why you work on your own bike or find a friend to help you.

Exactly.

[Untold]

Does that include the tow?

[goldarrow]

probably $150 for storage $5 for the fuse, and $20 for labor   

[Black 750K8]

probably $150 for storage $5 for the fuse, and $20 for labor   

$150 labor $20 fuse $5 beer. $50 any more questions. 

[bjatwood]

This is why you work on your own bike or find a friend to help you.

+1,000,000 These old bikes are pretty straightforward to work on IMO. 
And when you get stumped, this site will and can handle all situations!

[Untold]

This was extenuating circumstances. He was standing on the side of the highway an hour from home and gave me a call, but I could only be of limited help over the phone, and he had no tools.  Hence the tow.

 Then I think it was probably easier to see if they could sort it out so it could be ridden back home, rather than have to go pick it up with a truck. But I'd certainly question what they did.  If that was total price for tow/storage/labor, then not a crazy price to pay considering the circumstances at the time. 

[sammermpc]

Heh, yeah. Untold tried to help me out -- but twilight on a narrow shoulder on the side of I-95 didn't seem the time to really get into it. I poked around for a bit, but nothing came up.

Does that include the tow?

Nope, that's not including the towing. That was another $75, which considering that it was a big ol' flatbed and the guy dropped me off at the bus station (I had to get back for work Monday), seems pretty reasonable.

Altogether, I'm looking at something like $250. So yeah, I'm guessing it was ~$150 to tuck a loose wire back in that I didn't catch. I'd almost prefer that, rather than finding some janky fix that does cost that much. I'd rather just spend some time and go through the entire electrical.

Yeah, I could've had them store the bike in their yard, and rent a truck to drive down on Saturday and haul it back -- would've been cheaper. This way, I get to ride back at least .

Also, I'm definitely going to add a flashlight to my roadkit. That, and maybe one of these little pocket multimeters (http://www.adafruit.com/products/850). I'll definitely try that fuse replacement too: seems like a good idea.

[Untold]

Headlamp > flashlight

[sammermpc]

Just a quick update -- I got the bike back. Rode it up from Providence last week. Wires to the ignition had cracked -- they must have been pretty bad, or maybe a PO had done a poor soldering job. The shop spliced in a new length of cable, but I need to go over the whole. This weekend, maybe.