This was an update session more than a hands on wrenching session, but it turned out to be one of the more significant ones in this whole build. The key problem finally got solved, the tank came off the bike for the first time, and the CB750F gas tank hole turned out to be a lot worse than what I had been picturing in my head for the last several episodes.
Table of Contents
The Key Problem Is Finally Solved
After the lead on duplicate keys went quiet, my dad started looking into another option, the actual solution turned out to be a company called Cycle Keys Online
. It is a small operation where you send the guy the key number and he cuts a new key from an aftermarket blank to match. My dad ordered three keys for about ten bucks each, and shipping is free if you order three or more, so thirty bucks total for three working keys. Worth knowing about if you are dealing with a similar lost key situation on an old bike, since they cover more than just vintage Hondas.
With a working key in hand, the gas cap finally came off, which meant the tank could come off the frame for the first time since this bike arrived in my garage.
What the CB750F Gas Tank Hole Actually Looks Like
I knew there was a problem here. I had put my finger through it weeks ago and felt how big it was. What I was not prepared for was how it looked once the tank was actually off the bike and I rolled it over to get a real look underneath.
The rust that had been kind of bridging over the hole, holding itself together by nothing more than corrosion and luck, fell apart the moment I moved the tank. What is left is a hole that runs about eight inches long, rough and speckled along the edges, with loose rust still rattling around inside the tank itself.
I sent Jeff a photo with a tape measure stretched across the hole so he could see the actual scale of what he is dealing with before committing to anything further. He did not seem fazed by it at all. His read was that as long as we cut out all the compromised metal and patch around it properly, this is still a workable repair. So the plan with Jeff is still on. I just need to get a time scheduled now that the tank is actually off and ready to travel.
What the Inside of the Tank Looks Like
The side walls inside the tank are actually in great shape, which was a relief. The damage is concentrated where gas had apparently been sitting in a pool for a long time, since the bike had been stored on its side stand for years. That pooled fuel ate through the metal in one concentrated area rather than the whole tank corroding evenly. There is some residue on the opposite side too, likely from evaporation over the decades, but nothing that looks like it will fight back during cleanup once the hole itself is patched.
A Decision on the Tank’s Cosmetics
Here is something I have been wrestling with. The outside of the tank has some bubbling where rust has formed under the paint, along with flaking near one of the decals. There is also a small dent that looks cosmetic rather than structural, probably from something leaning against the bike during all those years in storage.
My instinct is to clean it up as best as I can and possibly clear coat over it for some protection, rather than fully repainting. Part of that is practical. The decals on this tank, the Super Sport graphics and pinstriping, run close to two hundred dollars for a full set, and I am not interested in spending that kind of money just to end up with a tank that looks too fresh compared to the rest of the bike. The bigger part of it is philosophical. This bike has patina, and I would rather the tank look aged and consistent with everything else than have one shiny panel that makes the rest of the build look rougher by comparison. A pinstripe with some age on it beats no pinstripe at all in my book.
The CB750F Rear Fork Came Off Clean
This is the part of the update I have genuinely been dreading since my dad first raised the concern about loose bearings packed in grease. The good news, and it is genuinely good news, is that this rear fork does not use that setup at all. There is a grease fitting instead, which means I just need to pick up a grease gun and regrease it during reassembly. No nightmare scenario with loose bearings trying to escape into the ether while I fight to get everything back together.
Getting it off the bike was not a one person job, though. My dad stood on one side with a breaker bar while I worked the other side with mine, and together we cracked the retaining nut free. Once that let go, the rear fork pulled out without much additional drama. There is grime from decades of flung chain oil to deal with and some rust at the ends, but nothing that looks beyond what the rust reformer and a fresh coat of satin black cannot handle. That rust reformer treatment worked well enough on the rear caliper torque link that I am planning to use the same approach here.
A New Workbench Is Coming
Not everything this episode was about the bike directly. The lift has become my default workbench by necessity, and it has gotten cluttered to the point of feeling claustrophobic. Every supply run for the bike somehow results in more stuff piling up in the one usable workspace I have.
My dad came through with a scrap plywood top for a proper workbench, about two feet wide and seven feet long, which gives me enough room to finally mount a vise and maybe a benchtop drill press down the line. Building the base and getting it set up is the next non bike task on my list, and I am hoping it also solves some of my lighting and camera angle problems since I will not be stuck working in the one dim spot between ceiling light runs anymore.
Where the CB750F Stands Now
The tank is off. The rear fork is off. The rear brake caliper situation is still on hold since that piston refuses to budge, and that is staying parked until it can get the heat treatment at Jeff’s place alongside the tank repair.
Looking ahead, the trunk is coming off next, along with the tool tray and the battery box. After that it is the wiring harness and what I believe are the ignition coils, which should bring me down to a bare frame from the neck back. Once that happens I can really go through and address every rust spot on the frame itself before starting to put pieces back on in reverse order.
The front end is the next major phase after that. I am already a little concerned about surface rust on the fork tubes, since pitting there can either chew up fork seals or let oil seep through if it goes deep enough. The good news on the brake front is that the front bleeder valve moved easily, which gives me some hope the front brake will not turn into the same fight the rear one has been. If it does seize up similarly, the front caliper is apparently shared with the K model, which makes parts easier to source than anything specific to the F.
Ride With Me
If you want to see how the gas tank hole turns out once Jeff gets his hands on it, subscribe to the WaltInPA YouTube channel so you catch that episode the moment it goes up. If you know someone restoring an old bike who is dealing with a similarly rough gas tank or a lost key situation, send this one their way. And if you want to follow along with the rest of this CB750F Restoration as it moves toward the front end, come hang out in the WaltInPA Discord where the community has already helped solve more than one problem on this build.
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