In March I bought a 1978 CB750 F SS resto-mod on Bring A Trailer fundamentally on a whim as a birthday present to myself. One of those really getting old fart birthdays where you are looking for lost youth. I was sitting at my computer at lunchtime and put in a last minute bid. I won. You can all see the bike, the associated youtube video and what I paid for it here:
https://bringatrailer.com/listing/1978-honda-modified-cb750f-super-sport/. Hold the potential laughter and beatings in writing to me. I have no previous experience with 750 SOHCs - ownership, technical, etc. but always liked them since I was a kid. I am a hands on guy with various cars and do HDPEs and have ridden cycles since a kid with a new '69 Mini Trail. Last bike was a 1981 GPz 550 which I sold in 2008. Trial by fire.
The cosmetics of the bike are what I wanted / want - a clean UJM SOHC resto mod. My gut and the photos told me this was a bike that was not in good enough shape or all parts in place to restore as a stock bike. OK by me, I did not want that. But, I was thinking it would be running and I would replace all the rubber and other stuff. The bike was delivered at night, after rolling out of the truck, I tried to start it, cranked over, but did not start. Exchanged emails with UMS and tried again a couple of days later. No spark at #4 spark plug, pulled the fuse box cover, main fuse distressed by not severed, looked at wiring and green wire in main harness and connector fried. Still turned over. So the main cause appears to be due to electrical / wiring system issues. The main fuse was / is distressed (but not blown). The green wire in the main wiring harness under tank and to the rectifier overheated and the insulation has melted and melted the connector(s) and black wrap of the harness. I am convinced the bike was delivered in this state, I would have smelled the burning insulation and connectors. The last email from UMS is a disgrace. Can send to those interested.
I have purchased all new wiring, harness, connectors etc. as plug and play and plan to install. I have quickly become a major customer for the major CB750 online parts suppliers - thanks to Parts N More, Vintage CB750 - these guys deliver.
However, I need to get to root cause so that I do not repeat the issue. I need to do some more research before making rambling requests for help from you experienced folks, but if any quick thoughts feel free to let me know. This thread is the start of that process.
I am replacing all rubber hoses and related gaskets. I have the battery box, oil tank and chain guard out for access and powder coating.
I have received feedback on how to replace the braided oil lines to and from the engine from the oil tank. Thanks, guys.
I will now be getting into more details.
