CB750K4 New project

[Rob62]

Just found this which may help....migt be useful to other non-electricians too
http://vsource.org/VFR-RVF_files/HondaWireColors.htm

[BigAl (Alan)]

Not sure which diagram your using? but the latest Clymer manual with colour coded wiring takes a lot of work out of the fault finding job.
I have attached an image of your spare RED spade connector, it has no function on the K4 bike

Alan

[Rob62]

Bloody hell! Just been studying the wiring diagram and noticed that the fuse box shows three different rated fuses, 7amp, 15amp and 5amp. However the haynes manual describes the fuse box as; “containing 2 spare 15amp fuses and the 15amp fuse necessary to protect the equipment” I read this earlier and assumed that only one position in the fuse box was live (the bottom position) and the other two above it were for spare fuses... but the usa k4 diagram says otherwise? Any help greatly received.

[Rob62]

Thanks Al, thats looks like a different (better) diagram to the one I have, found on the internet....

[Rob62]

So, inbetween visits from my kids i spent another couple of hours in the garage. Last night i did a bit of research on the wiring and found a few alternative wiring diagrams for the usa models....there seems to be a few versions out there which adds to the uncertainty....however. I now have working correctly; tail light, brake light, neutral light, oil light, headlamp, high beam, indicator buzzer, indicator relay but still the indicators do not work. They are new pattern items with two wires from each stem, i have them connected to light blue and green RH and orange and green LH, front and rear. The green earths on the healdlamp bowl are currently disconnected?...I believe the original indicators would have had a single wire through the stem (for the light blue and orange) and utilize the earths in the headlamp bowl?  I’ll persevere and get there in the end..

[Rob62]

Another sunny summer day spent in the garage..... getting a bit cheesed off spending all my spare time working on the bike, still its gotta be done.
Fitted the exhaust today, bit of a struggle but ok in the end. Still need to finish off a few bits, fit the chain, rear brake linkage, bleed the front brakes, fit the clocks, sort out the annoying leaky oil tube and one of the carb float bowls has a slight leak......  but she runs !! and sounds ok, no burning oil or nasty rattles (just normal sohc noises). Needs the carbs balancing but started up 2nd kick. Ended the day on a high.





https://m.youtube.com/watch?v=e0POPnciudA

[Spitfire]

Looking good, no scratch that looking great, I'd stop and admire it if I saw it parked up.

Cheers

Dennis

[JamesH]

Great work Rob, looking really good.

[Rob62]

Thanks chaps, i’m quite happy... although it certainly is nowhere near one of your top restos’s James.. The handlebars, mirrors, mudguards, headlamp brackets, wheels, lights are all original chrome and pitted but in keeping with the age. The tank is scratched here and there but again in keeping. So its a mixture of original patina and diy restoration. Still cost a few bob though 😳

[hairygit]

You may not think it's up to James' standard of restoration, but you have a good looking bike to enjoy the summer with. (That said, it's pi%*ing down here in Devon right now)

[Rob62]

Cheers HG, its baking hot here and has been for weeks now, once she’s mot’d it’ll start raining no doubt

[JamesH]

You may not think it's up to James' standard of restoration, but you have a good looking bike to enjoy the summer with. (That said, it's pi%*ing down here in Devon right now)

It’s all relative and Hairy’s exactly right - at the end of the day you saved another 750 and have a superb bike to enjoy the summer on. Enjoy and be proud of your work. It’s bloody hard work restoring these 750’s...but very rewarding..

[Green1]

Looks great.
Nothing wrong with a few scratches it shows its been used and enjoyed.
My bikes had enough people around them today so I'm sure yours would.

[Rob62]

Another frustrating day with no progress..... My original target for having this bike completed was the mallory festival on the 7th july, however despite having the bike built and running by the evening of the 5th, she developed a misfire which turned out to be the ht leads melting. I’ve never seen this before but as they are 45 years old i decided to draw a line under the problem and order some new ones. I took the NSR to mallory and then had a week in henly on thames sampling the local beer.... So today i set about replacing the old coils. They are from wemoto, i have used wemoto coils on other projects with no problems.. The first thing is to attach the correct connections onto the low tension wires. Assumption #1 that the black lead will be the power lead (b and w) and the yellow lead will be the points lead (yellow or blue)... both new coils had one yellow lead and one black lead with spade connectors... So when i make all the connections and then switch on the ignition and turn on the run switch she immediately blows the main fuse. I have double checked that the new connectors are on correctly i.e. black to black/white on each coil and yellow to yellow on one, yellow to blue on the other. Any ideas what would cause the fuse to blow? Would having the power wires (b/w) mixed up with the point wires (yellow or blue) cause a short?.... i need an auto electrician.. any help greatfully received... running out of fuses.

[K2-K6]

Not sure if it'll cause a dead short but at least protected by the fuse.

The points wires run straight to earth via the points back plate with the points closed. It's a bit reverse logic as you are switching the earth line when you'd normally, in a conventional circuit,  expect to be turning the power line on and off.

So the setup is,  positive to the coils via ignition circuit,  earth's switched by points.

Hopefully someone can shed some light on the wemoto wire colouring for you. But you've only got one other configuration you can go with, maybe switch over connection and try with new fuse.