Topic: '70 K0 Riding Along Just Quits

[Scootch]

So I'll be riding along or stopped at a light and the bike will just quit. It's as if turned key off. Electrical system seems to go dead. No neutral light. No oil pressure light. No headlight. I replaced the ignition switch with new thinking the original switch was the culprit. On the first ride after that it quit again. If I turn the bike off for 30 sec or a minute things come back to life and the bike will start and run. If it was the kill switch the entire bike wouldn't go dead. I'm not sure if it's heat related. Any ideas??

[ekpent]

Sounds strange.Two other area to check though is the fuse and holder especially if its the original factory just one fuse set-up. I had a K1 that was having a little problem there. Also make sure the mail/female plug for the ignition switch is nice and tight and fitting well.

[bryanj]

Battery leads tight at battery, ground points and solenoid?

[Scootch]

Where is the fuse physically located?

[Scootch]

I will do more wire and connection checking tomorrow...

[Don R]

 Look behind the left side cover. Remove it with care, they are brittle and if the old grommets are still there they are as hard as nails. I start at the bottom one and hold close to the tab, then top right and lastly the left one.

[Kevin D]

make sure the male/female plug for the ignition switch is nice and tight and fitting well

That’s what sunk my CB. My switch/harness plug (the plastic part) was mated fully, but one of the connectors
(the conductor part) was wobbly inside the plug. It got pushed right out the back of the plug and the male and female parts had no penetration, the ends were just touching, most of the time

I had already cleaned and lubed the contacts inside the ign switch.

[Scootch]

Well here is what I found... See attached pic
I found a fuse holder like I have never seen before. I don't know if it was original or not fuse holder contacts are loose and the fuse was blown. Looked like there may have been a tiny whisker of the fuse making contact. The two halves of the fuse holder plug together with the fuse in there as well. I wired in a new modern fuse holder with fuse. Hopefully that will take care of it...

[MauiK3]

It would be good to find an original.

[Scootch]

Is that fuse holder original equipment?

[Don R]

  The originals had a holder for spare fuses built in. I have a couple reproductions on my bikes, one doesn't hold the fuse well due to the rubber being too soft. I plugged a blade fuse in and am waiting for the repro to get old and hard lol.
  And thanks for the report. Often, we never hear what was wrong.

[bryanj]

Original fuse was a clearish plastic cylinder with a clip to fuse in each end that opened longways

[Scootch]

Thank you guys for responding! I appreciate you taking the time to share your knowledge. I feel that feeding back the solution to problems or info on what was found or encountered is the right thing to do.

[bryanj]

Correct, it all adds to the knowledge base

[Prospect]

You can replace the fuse holder with a car type blade fuse. You can buy a fuse holder on Amazon and solder it in. I do it with all my bikes.

[Don R]

https://www.partzilla.com/product/honda/32110-300-000?ref=4290e56e20a27c22d4c599d2c83c54355baf442b

 This is what came in my K0.

[thep1pe]

My 750 did the same as yours. It turned out to be a corroded and broken wire in the wiring loom at the steering header. It was broken due to the hardening of wires and the side to side movements of the steering. Hope this helps.

[Scootch]

Prospect - yes I went to the auto parts store and got a blade fuse holder..

Don R - Thank you!  I did some searching and saw that different places had that type and claiming if was for early CB's.  I may pick one of those up in an attempt to keep the bike more toward original...

[ekpent]

What amp blade fuse are you using in your new rig ?

[Scootch]

What amp blade fuse are you using in your new rig ?

I installed 15 amp.  The wiring diagram calls for 15.  I hope they are equivalent to the 15 amp round glass fuses?

[bryanj]

15amp is 15amp dont matter bout design

[ekpent]

So Scootch since we have you on the line do you have any fun stories or interesting history on that fine looking K0 that you have ? Is it totally restored or a nice cleaned up survivor ?  Glad to see you are out riding it.

[Prospect]

So Scootch since we have you on the line do you have any fun stories or interesting history on that fine looking K0 that you have ? Is it totally restored or a nice cleaned up survivor ?  Glad to see you are out riding it.

Yes, I'd love to hear as well.  Always interesting to hear.

[Scootch]

So Scootch since we have you on the line do you have any fun stories or interesting history on that fine looking K0 that you have ? Is it totally restored or a nice cleaned up survivor ?  Glad to see you are out riding it.

Yes, I'd love to hear as well.  Always interesting to hear.

OK...  Here are most of the high points… I had lusted after a CB750 for many years. I was 17 when they came out in '69. I owned a CL350 Scrambler at that time but was blown away with the enormity and the sound of the CB750. I have never forgotten that sound. 1970 was the year I graduated from HS. Thus the special significance of the '70 CB to me. This machine was located in Arizona and obtained from the son of the original owner with ~4300 miles on the clock. The gentleman that located it brought it back to Florida and performed a refurbishment on everything except the deep entrails of the motor. Some of the parts are original and have been re-chromed. Many parts are new old stock from Honda. The fenders are original  re-chromed. The painted parts were purchased as a set from Yamiya. The rims are new from DID. 98% of the hardware is new from Honda. Wiring harnesses are new. Seat is new. Pipes are HM300’s. Last fall I was in Florida and came across the gentleman that had it. At that point I couldn’t resist any longer and 52 years later I had my CB750. I have spent the past couple months getting acquainted with it and learning about it. I have had to troubleshoot and repair a couple things and I changed the front and rear sprockets. I learned how to sync the carbs. I am pretty familiar with the type of carbs bcz I’ve had other bikes with similar. I have been watching plenty of CB750 videos on YouTube. I hope I don’t get bit with something major in the motor but if need be I will rebuild it in my basement. I plan on riding it – and have been. It is not going to sit on display. It is a blast to ride and it causes a stir everywhere. I enjoy seeing the look on people’s faces – even on those people who are not necessarily cycle enthusiasts. People just seem to know that there is something special about the bike… and there is!!

[ekpent]

Thanks and great story,glad you found a nice one. They are definitely conversation starters for sure whether around a simple gas stop or a show or something else. Lots of people have a memory of owning or knowing somebody or just have a soft spot for them in general. Even the tough older gritty Harley riders seem to have a little story on them when they were younger just starting out riders. Enjoy !! --  Eric