Topic: Did my Steed have a Myocardial Infarction or a Stroke?

[ChefJoe]

Alright already!!!
Here's my new problem...
Yesterday the 'Ol 750f was running great. I took it for a few spins and then parked it while I finished cleaning out my garage. I pushed it in for the night but this morning I went to start it to ride to work and nothing... no lights, no nothing. I checked my cables; nothing out of the ordinary. Hooked the battery up to the charger and it had juice. The wiring system is pretty rigged (tape, paperclips, etc.  ) but the fuses I saw were good. The previous owner had done some weird things like rig a toggle switch for the ignition- I don't need the key which is good since I lost it
I know absolutely nothing about electrical work so any trouble-shooting tips y'all can give me are greatly appreciated.

[Bob Wessner]

The fuse may look good, but not be, or, maybe bad contacts in the fuse box, OR bad ground connection, maybe it's corroded. I would a least start with these since you had power then all of a sudden it was gone.

[ChefJoe]

Thanks... I'll try those in order. It can't be too difficult.
I

[Geeto67]

rewire your bike. bad wiring will only cause you more problems down the line. find a way to fix the broken leads and get rid of the paper clip wiring.

[frostypuck]

Key switch. Get one. They are about $25, they go bad on these (77/78 750's, 750F's, 550's after '76) bikes like crazy. Now, the p.o. may have cut the harness to wire in the toggle switch. (I have done the toggle switch thing, myself, but I don't cut the harness)
In which case it's probably best to put in a new harness. You can still get brandy-new ones for about $100, may seem expensive, but a lot less than burning your bike down.
Good luck,
Chris in Boston

[78_SaltLick]

Did you try kick starting it?

[Geeto67]

Did you try kick starting it?

if the key switch, the points, or the kill switch is shorted out, all kick starting will do is wear out your knee. All kickstarting does is manually turn the engine over, it does not magically make spark where there is none. If there is enough battery juice to turn the engine then the battery isn't the problem and kickstarting will do nothing.

[eldar]

It could be possble that the toggle just died as well. Since your ignition also turns on the lights, if the toggle is bad, then you will have no lights. Check that first since all you need to do is jumper the connection.

[ChefJoe]

I got it going...
I checked the battery- good, I replaced all the fuses, I bought some terminal spray, sprayed the heck out of everything and put the battery back in. It fired right up.
My starter does not work so I have to kick-start it anyway... that's next on the list. Then re-wiring the thing.
Is there a way to get a replacement key? I can't get under my seat which might pose a problem if Da Man decides to pull me over....My insurance papers are in there! I guess I'll start carrying them in my wallet until I get it fixed.
Next time I have a problem (and I will!), I'll do my best to figure it out before posting such silly questions 
Thanks for the help.

[Jonesy]

Is there a way to get a replacement key? I can't get under my seat which might pose a problem if Da Man decides to pull me over....My insurance papers are in there! I guess I'll start carrying them in my wallet until I get it fixed.

Try out www.hondakeys.com. You'll need the number off the cylinder of the lock.

[ElCheapo]

I say this only because I have seen bikes burn to the ground because of bad wiring. Keep your eyes open on eBay and you could get a complete wiring harness for about $25. Same for the starter. The harness however is more important, the starter most likely wont burn your bike up.

[ChefJoe]

 
Now my blinkers ain't werkin!

[Geeto67]

sounds like either your handlebar control or blinker solenoid.

Wiring harnesses are not hard to come by for these bikes, seriously think about investing in one so you don't go through this every week (once something starts to go in the harness then other things go as well).

When I laid my 75 down last year, the handlebar had pinched some wires and grounded them out, others the triple clamp did the same thing. Go over your existing harness, and find any breaks or questionable connections. Those not held by a connector you should solder and wrap in srink wrap or electrical tape, for ones with a connector take a look at the connection and replace as necessary with water proof connectors.

[ChefJoe]

Doin' it again and it's parked at work next to my freezer dead in the water
How hard is it to replace the harness?
I know NOTHING about that stuff and I might have a hard time tracking down any weirdness.
I poked around with a multi-tester but I'm not sure what to poke to find what is wrong. It's got power in there but when you flip the toggle switch (bypassed ignition switch), none of the lights come on. I rode it to work this morning and it ran fine. When I got on it to go home.... not a damn thing!
I spent over two hours messing with it in the loading dock to no avail.

Oh Steed why hast thou forsaken me?!?!?!?

[KB02]

Unplug your battery... to be on the safe side (no power=no fire)... and then buy a new harness. As long as you take your time it's not that hard to replace.

My suggestion - Use a nice new role of masking tape and a Sharpie Marker. Make all ends that you know where they go. Oce it's all in place, the you can simply remove the tape and plug in the wires (no nessassarily in that order).

[ChefJoe]

I guess you gotta do what you gotta do...
Any advice on how to talk the wifey into the idea of a new bike? I'm sure some of you fellas have had to do it at some point
Then I could make ye olde 750f into the Cafe bike I've dreamed of

[Geeto67]

Why woudl you get rid of a bike that for about $20 in supplies from home depot you could rewire yourself. A clean used harness off of ebay is a heck of a lot cheaper than a new bike. If you get the correct harness for your bike rewiring it is as simple as matching the color coded wires together and slipping it into the back of the headlight and factory attach points. With all the parts in hand swapping a harness takes about 3 hours including putting the bike on the mainstand, pulling the headlight and test rides when you are done. YOu are too far away from me otherwise I would come over and do it for ya just so you can learn. Seriously if you can fit the round peg in the round hole and match up colors you can do this, its just tedious work and you have to psych yourself up to do it.

Someone here can give you a wiring color diagram for your bike that should help.

Anybody here close to ChefJoe who can go over and help him sort this out. Wiring problems are usually no good to diagnose unless you can see them.   

[ChefJoe]

 
I'm NOT gonna get rid of it... just add to the stable! I love this bike.
Thanks for the encouragement, though. I must admit that all those wires intimidate me but I'm up for the challenge!
... shoot... if there is anyone near to help, I'd be happy to cook them dinner and buy the beer.
I'm a pro at that!
Is there a way anyone could email me a color diagram of the wiring?
Thanks Geeto67!

[ChefJoe]

Would this work?

http://cgi.ebay.com/ebaymotors/SOHC-CB750-Complete-wire-harness-wiring-elec-No-Res_W0QQitemZ4575144895QQcategoryZ35594QQssPageNameZWDVWQQrdZ1QQcmdZViewItem

[ChefJoe]

Is this one better?

http://cgi.ebay.com/ebaymotors/Honda-CB750-CB-750-Wiring-Harness-No-Reserve_W0QQitemZ4574387797QQcategoryZ10066QQssPageNameZWDVWQQrdZ1QQcmdZViewItem

[Geeto67]

The first link is a butchered harness. I don't like the look of randon 3m connectos on the headlight piece plus he said that the turn signals were clipped as is the headlight. for 99 cents you could use ti to replace the butchered wires in your harness, but rather than do that just get one that is in good shape. The second link looks a heck of a lot better so you could go with that. However there seem to be 7 other bidders so there might be a bid war that will drive up the price. (try sniping). The other thing I don;t like is that they never tell you if the harness is a cb750K or a cb750F. If I recall correctly the f harness is slightly different althought I can't remember what. It might just be that the F taillight wires are longer to accomidate the tail section. From the looks of his other parts I'd say that harness is a K bike. Maybe someone can chime in here and state the difference between a K and F harness. Otherwise I say go for it.


The best way to replace a harness is to start from the rear, lay out the new harness next to the old one, and as you unclip and remove the old working back to front you clip into and install in the clips the new. Sace the big headlight bucket  jumble for last becauseit makes it easier to hold. 

[ChefJoe]

OK, I'm pretty embarrased, but It's running now.
Turns out it was a fuse They looked fine at first but upon closer inspection... bad.
I'll be replacing the harness ASAP, but at least it's running!
Is the main fuse a 15 amp fuse?

[Geeto67]

OK, I'm pretty embarrased, but It's running now.
Turns out it was a fuse They looked fine at first but upon closer inspection... bad.
I'll be replacing the harness ASAP, but at least it's running!
Is the main fuse a 15 amp fuse?

Yeah the main fuse is a 15 amp one. Personally on a butchered 750 you'll probably blow fuses once a week if your wiring is as bad as you say it is. Even the most finely tuned cb750 will pop at least one fuse in the course of a year if it is ridden regularly. I usually run a 17 to 20 amp fuse in there under the assumption that whatever is causing it to pop will burn out and smoke and save me the time to diagnose it (just kidding, sorta). Actually I get about 2 years out of a 17 or 20 amp fuse and it has not had any adverse effects on my bike to date (and I've taken some long trips on that sucker). IF you are popping a fuse you definatly have a short somewhere and I would go over your harness and find out what is shorting out.

[ChefJoe]

Thanks Geeto!!!
I'll be doing the harness thing soon... and  tires, paint, etc.
Some dumb questions from me coming soon... y'all have been warned!