Topic: A Noob's Build of a '78 CB750k

[Boulevard_beck]

I decided to relocate the ignition key and fabricate a new ignition button and kill-switch holder today. Sorry for the cell phone pics, but that's all I had on me while I worked this afternoon.

I picked up the ignition bracket for $34 and the ignition assembly for $79 at Z1Parts.net. I have a 78, but the ignition is for a stock 76 or earlier, I think. This caused a bit of an electrical issue since my stock ignition assembly has 5 wires and the one from Z1Parts only has 4 wires. Turned out that it's no biggie because two of the wires are brown and basically get crossed anyways. I also cannot lock my steering anymore...but I never did that with my Honda anyways.



I wanted to relocate the ignition to the side of the bike up front, but my frame was too wide and the bracket wouldn't fit properly. So, I ended up putting it near the rear brake switch and right beside my aftermarket external crankcase filter.



In order to do this, I needed to extend out the wiring to reach back the, so I created one with some stock coloured wires, solder, shrink wrap and wire wrap...remembering to cross the brown wires. I zip tied the new length of wire to the frame under the gas tank and hooked everything back up. A quick test and it works perfectly.



The only issue is that my location for placing the ignition didn't fit well with the side cover. After a few minutes with the hacksaw and a hand grinder, I was able to cut out a section of the side cover to make it fit. Kinda brought a tear to my eye, but I'd like to get rid of these plain old black side covers in favour of some nice ones with the "750" emblems next year before i paint it anyways.







Next, the ignition button bracket. The previous one just looked ugly because it had to share space with the ignition itself. With all of this room, I started out by mocking up what it would look like using cardboard. Once I got it all figured out, I stencilled out the shape onto my $5 piece of plastic from Home Depot and cut, drilled and sanded it all out.



After a quick paint job, it's all set to be installed. I hooked up the buttons and installed it. The arcade button has such a huge backing to it that I needed to bend the button bracket a bit to give room, but it all went pretty smoothly.





Here's the end product. Looks a lot better than before, I think.

[Denotslaer]

Great work so far ! Is there any way to shorten the shaft/internals of the arcade starter button . If so that would provide some much needed room . Also , have you considered fabricating a "box" type enclosure for those buttons ? They look as though they are welcoming rain/moisture in their current state ...




DENO

[Boulevard_beck]

With some effort, yes the arcade button could be shortened. I'd have to cut out a section of the middle and glue it back together shorter. Too much work for me, though.

And for the waterproofing, I have some 2" heat shrink tubing that I'll put over the button and wires and wrap it all together...should be good enough. I ride the Honda in nice weather...I have another bike for rain/snow/hail/ect.

[Maksimum Hops]

Just wanted to say I've really enjoyed this thread so far - especially seeing how much work you have gotten done in such a quick time. Also, great quote:

Blinkers not blinking...carbs are your issue.

[fr33man]

Last night I spent some time completing the wiring on my speedo indicator lights. A few of the wires threw me off, so I might post a quick cheat sheet on how I hooked up the Dime City speedo to the OEM wiring and got everything working.

The big achievement was building my own 2 into 1 diode. The OEM indicator cluster had two lights - one for each turn signal. The Dime City speedo only has one turn signal indicator light. So, I needed to connect both signal lights together for the indicator to work regardless of which signal was blinking. The purpose of the 2 into 1 diode is to allow the left and right signal lights to be connected together, without actually "shorting" each other out. The diode only allows power to flow up to the indicator light, not back across to the other signal light...otherwise you'd hit left signal and all four lights would blink.

You can buy a 2 into 1 diode for about $7, but you can just make your own for about $2 in parts and 30 minutes of effort like I did. I simply soldered together two 3 AMP diodes...



And then added some heat shrink wrapping...



And finally heat shrink wrapped the entire thing all into one nice tidy unit.



Then, I hooked up the two leads to each of the turn signal light power wires, and the single lead to the speedo indicator light and it works like a charm! Saved myself a couple bucks and about a week of shipping cost/time to Canada.

great info - just what i was looking for - ill do the same in a few hours =))

[onetruepunk87]

I'm working on a '77 CB750k, just wanted to thank you for posting your "cheat sheet," it really helped me out installing my mini gauges.

[VTNick7]

Great little cheat sheet! I am having trouble with my new gauges and will use this thread this weekend when I can tackle that again.

[NP3]

I will second everyone's sentiment that the speedo wiring cheat sheet is very helpful.

I just want to point out that the oil light wiring may be a little off.  The red wire coming out of the new speedo should go to a power source (any black) and the red/black wire should go to the oil pressure switch (blue/red).  The oil light wiring is similar to the neutral light, which you have correct.

I have yet to wire up my speedo, but the above seems correct based on the stock wiring diagram.

[Prez1967]

Just read this entire thread.  Excellent work!!! Hows it been running since? Anything new?

I recently bought a '78 just like yours and even though it ran fine coming home, I am in the process of digging into the different systems and rebuilding/restoring where possible.

Very inspiring to see someone with very little experience getting so deep into this stuff!

[Boulevard_beck]

Just read this entire thread.  Excellent work!!! Hows it been running since? Anything new?

I recently bought a '78 just like yours and even though it ran fine coming home, I am in the process of digging into the different systems and rebuilding/restoring where possible.

Very inspiring to see someone with very little experience getting so deep into this stuff!

Thanks for the comment. The bike is still running really well, except for the accelerator pump that I never got around to fixing. I put a few thousand miles on it last summer, but then I bought a new motorcycle. Unfortunately with a family and kids and a new bike, the Honda gets the short end of the stick.

My new Ural however gets a lot of time on the road
http://youtu.be/N-nbw0a1RuU

[Restoration Fan]

I have to say I enjoyed the heck out of this thread.  Loved all the photos and explanations and especially enjoyed the sense of humor.

Just purchased a 78 750K for my son to rebuild as his senior project in high school.  We have been watching YouTube videos, reading threads on forums and speaking to local restoration specialists (a quick word of thanks to Atlanta Motorcyle Works in Woodstock, GA for being willing to let us look at restored 78 750K and answering the questions of people who just walked in off the street that they had never met.  They run a very impressive shop and I figure we'll be giving them some business when we get to the carb synching stage.)

Just wanted you to know that now, even a couple of years after you posted this, other people are finding it helpful and enjoying the posts!

[juan_carlito]

Found this thread while looking for info on the dime city cycles mini speedo . . . must say after a quick scroll through I will definitely be coming back to read everything and grab some info!! Solid work. And a fellow Canadian as well makes it even better!

[RandyBMC]

I wanted to thank you for the cheat sheet on the DCC speedo wiring.  I have a simple question though.  When you are taking the orange and blue from the wiring harness on the handlebar switch, they would normally go to the turn signal.  Are you using the supply wire (solid orange and solid blue) to the turn signal to power it from the handlebar switch, then jumping that to continue to the indicator? 

So you have to add an additional solid orange/blue?

Thanks!  If anyone knows the answer, since this is an old thread, I would appreciate the help.  I'm using a two wire bullet turn signal from DCC.

[calj737]

I wanted to thank you for the cheat sheet on the DCC speedo wiring.  I have a simple question though.  When you are taking the orange and blue from the wiring harness on the handlebar switch, they would normally go to the turn signal.  Are you using the supply wire (solid orange and solid blue) to the turn signal to power it from the handlebar switch, then jumping that to continue to the indicator? 

So you have to add an additional solid orange/blue?

Thanks!  If anyone knows the answer, since this is an old thread, I would appreciate the help.  I'm using a two wire bullet turn signal from DCC.

Yes, and you need to add a diode inline to prevent power from the left side bleeding to the right and vice-versa. Else, all 4 indicators ignite with either side switch.