Several small technical questions...

[Needforsteve]

Hello CBer's!

So I've gotten my '81 Custom to school and have begun to disassemble it. I've got the airbox and carbs off, I've pulled the battery box out and the guage pod is off. What I'm wondering are these things...

Concerning wiring; I plan to rewire/build my own harness since the stock harness has shorts in several places and has been hacked into more than I'm comfortable with. I plan to relocate and replace the stock fuse block with a blade fuse panel. Anyway, What's worrying me is the charging/ignition system. I've got a Clymer manual with a great diagram, but my eyes still go all swimmy when I think about how the charging/ignition wiring is going to have to be organized to run. Does anyone know of any specific diagrams or write-ups for rewiring, specifically, the charging and ignition systems?

For the battery box; I plan to locate the fuse block and new ignition switch down around the battery area, probably behind them. Does anyone know of any good ideas on how to mount these? I'm thinking a metal project box from Radioshack but I'm looking for other ideas...

Also, the guage pod. Mine doesn't resemble any other '81C guage pod I've seen. Those have all been Speedo/Tach with a vertical row of warning lights between them. Mine has Speedo/Tach with 4 seperate warning lights in a square, just above the odo/trip. What year bike is my guage pod from?

[TOOLS1]

If you go to this thread, there is a simplified DOHC wiring diagram posted there. http://honda-cb750-s.456789.n3.nabble.com/1980-Honda-CB750F-The-Honey-Badger-Bobber-Project-td3835481.html
As for a place to mount your wiring, I would suggest an ammo can.
TOOLS

[LukeM]

Picture of the current gauge cluster, please?  images.google.com may be of some help determining what you have, and/or what you need.

Luke M

[Needforsteve]

@TOOLS that's the business man, thanks! Finally a nice diagram not drawn like a dang cartoon!

...and I actually really like that ammo can idea too, but I wonder if a standard .30cal can would fit in the battery box area? Are there ammo cans smaller than that?


That's how the guages I have look. I'm deleting them anyway in favor of a single speedo, but knowing what they're from might help if anyone could use them. That picture says '79.

My plans for the moment are to wire it bare-bones like that diagram, with Hi/Lo beam headlight (can that be switched with a simple SPDT toggle switch?), rear running light, brake light circuit and a turn signal circuit. Ah, and a plate light in case my plate bracket winds up too far from the taillight. Anything else I should think of wiring-wise?

[Re-run]

Single unit huh. that would clean things nicely. You have a couple options. You can find a unit from another bike, or by an electronic unit.

Getting one from another bike has the issue of not matching the speedo drive unit. This will throw off the speed reading the new speedo would give you.

An electronic unit uses a sensor that mounts to the bike. Accurate but can be expensive.

[Truck]

You can find stock speedo on ebay kinda cheap. You'd just need to fab up a bracket to hold it.

[shinyribs]

Don't forget the starter button and the charging circuit. :)

I'd really love to see what your existing gauges look like. Sounds interesting.

[Needforsteve]

Oh starting and charging are in the diagram, the other stuff is what all lights I'm including. The picture posted above is what they look like, just without the plug cut off.

I believe the stock speedometer ratio should be 2240:60, so I'll be buying something that will work with a stock-style cable. I don't care much for the big black plastic pod, and I like the idea of less in my field of view over the bars...

[shinyribs]

Yeah, you're correct on that speedo ratio. Even my '96 F3 front end on my '80 still uses that same ratio.

And I misunderstood your gauge description. I thought you had only one clock- speedo and tach combo.

[Needforsteve]

More questions! Can you tell I'm new to two wheels?

Anyway, here she in at the present;


I'm planning on using the tank that was on it (which I believe to be a 750K tank), but I'm still split on the seat. I could put a low, long cafe style seat on, but I want to be able to ride this bike to the beach. That's a 120~ mile trip from where I live, so I don't know how a cafe style seat would do for comfort. Any experience with this?

I'm also split on whether to run a bobbed rear fender or just replace the rear fender mounts with a grab bar and hang the light and plate behind the seat. So many choices!

...Also, anyone ever use Radioshack project boxes for ignition/wiring boxes? Alternatives smaller than an Ammo can?

[shinyribs]

You can hide oodles of wiring in your headlight bucket like the factory does. Plus it puts most all of your connectors at a very easily accessible spot for unexpected roadside repairs.

Have you considered running F body parts? IMO, they're pretty sporty looking and those seats are eternally comfortable.  

[Needforsteve]

Those F seats do look nifty  I won't be running side panels though, I have another idea for those.

I don't plan to have any excess wiring in the headlight bucket though, Excepting perhaps housing the Turn Signal flasher. I've already pulled the stock harness and am wiring the bike for minimal waste, so the only real bunch of wiring will be at the plugs by the battery for the rectifier/spark units. The new fuse box will be in this location also, so I'd like to close that up in something, possibly the same enclosure as the ignition.

[shinyribs]

Tha F tails look cool shortened, too. But the F tanks look so unfinished without side panels.

[Needforsteve]

There's a couple F seats with the fairings on the 'bay for $90~ or so. Tempting!

[Needforsteve]

So I've split the harness open and am, going by the diagram, pulling all the accessory wiring out. Not looking too bad so far.

Starting the bike with a screwdriver for however long it's been being done has melted the connector at the starter relay to the relay housing, so I'm gonna have to replace the pigtail connector at the relay. Does anyone know where I can purchase a duplicate of that plug? or will a new relay come with a plug to be spliced in?

Also, I'm gonna need a couple engine mounting bolts. I'm missing one of the long ones across the bottom, as well as some of the sub-frame bolts at the front by the head pipes. Anyone know a source? Google is useless in looking for these...

[TOOLS1]

Which connector are you needing? As for the motor mount bolts, just use 10mm, or 3/8 threaded rod. I like to use it with an acorn nut on each end. Looks really cool.
TOOLS

[Needforsteve]

It's the 4-wire connector than plugs into the top of the Starter Relay, by the 30A main fuse. Would a standard 4-wire connector from VintageCB750 do the job? I can't get the plug out of the connection at the Starter Relay so I can't look and compare.

10-4 on the threaded rod

[TOOLS1]

You should be able to get the correct connector from vintagecb750. However if they do not have it, there are several sites online that sell motorcycle wiring, and connectors. Also if you are careful you can remove the terminals from the connector, and install them into the new one. However if they are bad, you will need the special wiring crimpers to install them.
TOOLS

[Needforsteve]

Gotcha. I'll check Vintage CB750 again.

Dug into the carbs today, replacing gaskets and cleaning jets. Gotta order a new pilot screw and carb float, someone had broken the #4 pilot screw completely off.

I picked up my fuse block today for the new harness, and looked at ignition switches available at Advance. Will a 15A switch suffice or should I be looking for a 30A switch to match the main fuse rating?