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1971 CB350 . . . 40 year hibernation

stl360+450

Veteran Member
Joined
Aug 6, 2021
Total Posts
2,789
Total likes
288
Location
St. Louis, Missouri, USA
Two of my friends reached out to me in November 2019 about an old Honda in the wife's parents' shed. They sent a couple of pictures of what looked like a CB350, buried amidtst a wide array of items one typically finds in a shed forty years after move-in. Fast forward two and a half years to last week and I checked in about the status of the bike. There is a title, but (a) it was never transferred from the previous owner and (b) the VIN on the title shows CL, while the VIN plate on the frame shows CB. The numbers on the title and frame match otherwise. It has what appears to be a CB seat and tank, but has high pipes. I understand it was a fairly common mod for CB owners to adopt high pipes back in the day and the title was issued several years after manufacture, so my guess is that someone incorrectly titled it as a CL after a sale due to the high pipes. The last registration seems to be 1979. The current owner recalled that the timing was off way back when and that it was never fixed. That's how it ended up in the shed. The exhaust was not on the bike, nor were the covers for the rotor, points, and valve adjustment. The frame welds for the left foot peg support failed at some point in the past. The rear brake linkage is very bent. It is also missing lots of little things, like the spacer for the rear axle, center stand, air boxes and side covers, rotor/points covers, engine mounting bolts/brackets, etc. The motor turns easily and currently has plugs in it, so I was hearing some oil sloshing around as I turned it over by hand while also feeling some yet to be measured level of compression.

The husband and I disassembled the bike enough for me to load it in my . . . VW Golf. It's now home and I am hoping that the current owners will complete the title transfer if I cover the fees (including late fees), which would then allow for a legal sale to me. If I end up taking this project on, it will probably sit on the back burner for a little while.

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If only that bike could talk, the interesting tales it would have I'm quite sure. Lots of things to look at right away like the extensions on the front fender mounts and the trials tire on the rear tells me someone rode it in the dirt and from the broken footpeg mount, probably pretty hard. That's definitely a long term project. I'm honestly quite surprised the engine isn't stuck after sitting for who knows how long with no exhaust on it. It has a CL front fender and left passenger peg so that aligns with the title. At least if the points were replaced the terminals were attached properly, LOL
 
And you know that somewhere in that shed there's a box with most of those missing parts, because somebody took them off trying to fix it. You may never find it but they never threw anything away so it's still somewhere within 100 feet of where you found the bike.
 
And you know that somewhere in that shed there's a box with most of those missing parts, because somebody took them off trying to fix it. You may never find it but they never threw anything away so it's still somewhere within 100 feet of where you found the bike.

I was given a bucket of loose parts and the opportunity to check the shed, but with the amount of things in the way, I gave up fairly easily.
 
If only that bike could talk, the interesting tales it would have I'm quite sure.

For sure. It's a shame that the current owner never even got it registered. He hung out in a lawn chair as we took the bike apart for the ride home and seemed to enjoy watching us work despite not being healthy enough to get involved.
 
I'm sure this 350 will be similar to my CB350K1, a project for when my other projects are finished. The PO is a Norton guy and had this 350 as a daily rider until it needed an overhaul, so he rebuilt the engine (suspect work BTW, it doesn't turn over) and was going to finish the bike when his Norton blew up and he needed money. I got lucky and found it just as he listed it at HT, and I bought it knowing I didn't have the time to get into it for a while. It'll give you something to do down the road and even if you don't keep it, the upside will be a little profit if you just do the basics to make it functional and safe once finished.
 
It looks a lot better than what I started with. And if the Hig CL Pipes are in good shape than you have something very desirable.
 
It looks a lot better than what I started with. And if the Hig CL Pipes are in good shape than you have something very desirable.

Thanks for the encouragement. The exhaust seems to be in pretty decent shape. The headers are in similar condition, mostly clean with some scratches and a little rust.


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I see a run of telltale rust pinholes along the bottom of the lower muffler that should get looked at, at least from the vantage point of that picture immediately above. Hopefully it's just the outer shell and not rusted/loose internals.
 
I see a run of telltale rust pinholes along the bottom of the lower muffler that should get looked at, at least from the vantage point of that picture immediately above. Hopefully it's just the outer shell and not rusted/loose internals.

There was some surface rust on that edge and the side lighting from a basement window gave it the appearance of pinholes. I cleaned it up just a little with steel wool for the picture below. Insides don't rattle, but I haven't shined a light inside yet.


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Thanks for sharing this. I'm looking forward to following the thread! (If you end up owning it, that is. I had to wait almost a year to get the title on my 350F sorted out...)
 
Thanks for sharing this. I'm looking forward to following the thread! (If you end up owning it, that is. I had to wait almost a year to get the title on my 350F sorted out...)

Thanks. I'm hoping the title will get sorted, but not holding my breath. If it doesn't work out, I will look to move the motor, exhaust, and other serviceable parts on to those who can use them.
 
In California it's often easier to just say the title has been lost. If the bike is out of the system's records - usually after 10 years of complete inactivity - you have to produce a bill of sale and have the seller sign off that the title is lost (there's form for that, of course).
 
I decided to have a look inside the carbs this morning. They don't look too bad aside from the weird dried up residue - not sure what that is from. The chrome on the tops, however, has seen better days.

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Just my $.02 but the Chrome Tops have nothing to do with the Carbs ability to perform and are available from several sources as replacement and decent prices.
Many here have also either Painted or Powder Coated them.

It all about the insides and adjustments that matters.
 
Just my $.02 but the Chrome Tops have nothing to do with the Carbs ability to perform and are available from several sources as replacement and decent prices.
Many here have also either Painted or Powder Coated them.

It all about the insides and adjustments that matters.

Agreed. The 350 carbs seem like they should clean up okay and I'll be fine with painted (or maybe powder coated or replated) tops. I gave up on those 360 carbs based on the slides. They were completely frozen by corrosion as that bike had been sitting outside for quite some time. (The tank, exhaust, and seat pan were all rusted to the point of structural failure.)
 
That's definitely the hard way to get a bike home. Best part was it needed to be disassembled anyway, so you got a head start.
 
That's definitely the hard way to get a bike home. Best part was it needed to be disassembled anyway, so you got a head start.

The 360 was my first shot at reanimating an old bike, so it took me several hours over the course of a week to break it down sufficiently for the trip home. With the current 350 it took less than two hours, although it barely fit into my Golf.
 
The 360 was my first shot at reanimating an old bike, so it took me several hours over the course of a week to break it down sufficiently for the trip home. With the current 350 it took less than two hours, although it barely fit into my Golf.

Clearly you need a small pickup. :) But you're gaining disassembly skills in the process. Taking one apart is always easier than putting it back together.
 
Just my $.02 but the Chrome Tops have nothing to do with the Carbs ability to perform and are available from several sources as replacement and decent prices.
Many here have also either Painted or Powder Coated them.

It all about the insides and adjustments that matters.

Well, if corrosion gets bad enough you may end up with holes or the spot weld up top coming off. That holds the small barrel the slide spring sits on


Sent from my iPhone using Tapatalk
 
My friend's parents are going to try to sort out the title, but I don't expect to hear anything for a couple of weeks. The VIN makes the bike a CB350K3.

The welds supporting the left side of the "step bar" rusted through and broke off of the frame, so I am brainstorming about how to proceed. One option would be to try to repair the welds, but I am also considering clamp-on pegs. Does anyone have experience with pegs similar to those shown below? Are they secure enough to support the rider's weight while standing? If I use something like this, I will also be looking for a solution for the side stand, which also attaches to the step bar.

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My friend's parents are going to try to sort out the title, but I don't expect to hear anything for a couple of weeks. The VIN makes the bike a CB350K3.

The welds supporting the left side of the "step bar" rusted through and broke off of the frame, so I am brainstorming about how to proceed. One option would be to try to repair the welds, but I am also considering clamp-on pegs. Does anyone have experience with pegs similar to those shown below? Are they secure enough to support the rider's weight while standing? If I use something like this, I will also be looking for a solution for the side stand, which also attaches to the step bar.

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No way. I think those are just a foot rest for extending your legs forewards on a crash bar. I could see those being the cause of a serious crash if you trusted your weight on them. I think you should find a welder to repair the mounts on the frame for the original foot rest bar.
 
The pegs in the picture are foot rest pegs, definitely not up to any hard use.
Best option is to repair the frame section, there's a good chance the frame is weaken by rust if the bracket rotted off. May be a crashed/broken frame you can cut the section out of. Or make the box section and have it welded in, doesn't have to be a box but could be a solid bar with some machine work done for fit.
 
No way. I think those are just a foot rest for extending your legs forewards on a crash bar. I could see those being the cause of a serious crash if you trusted your weight on them. I think you should find a welder to repair the mounts on the frame for the original foot rest bar.

I was skeptical and definitely don't want to end up riding Flintstone's style. I was surprised to see even highway pegs that don't have any sort of through bolt to prevent rotation.

The pegs in the picture are foot rest pegs, definitely not up to any hard use.
Best option is to repair the frame section, there's a good chance the frame is weaken by rust if the bracket rotted off. May be a crashed/broken frame you can cut the section out of. Or make the box section and have it welded in, doesn't have to be a box but could be a solid bar with some machine work done for fit.

I am definitely planning to give the frame a more careful inspection. For whatever reason, the rust seems very localized at first glance. I was wondering if it might be smart to have a solid plug welded into a portion of the lower frame and then add a suitable support for the step bar.
 
I was skeptical and definitely don't want to end up riding Flintstone's style. I was surprised to see even highway pegs that don't have any sort of through bolt to prevent rotation.



I am definitely planning to give the frame a more careful inspection. For whatever reason, the rust seems very localized at first glance. I was wondering if it might be smart to have a solid plug welded into a portion of the lower frame and then add a suitable support for the step bar.
It might be the best route. I would be flipping the frame upside down, stripping all the paint off and then start tapping with a punch and tap hammer to find any weak sections. You'll see the difference between a solid section and weak by the denting, really weak the punch will go thru.
 
It might be the best route. I would be flipping the frame upside down, stripping all the paint off and then start tapping with a punch and tap hammer to find any weak sections. You'll see the difference between a solid section and weak by the denting, really weak the punch will go thru.

I think Tom was correct when he observed that this bike was ridden hard at some point in reference to the broken step bar. The frame tube feels solid, but it looks like someone may have already done some patchwork welding on it. My guess is that it was broken and "repaired", but not protected from rusting afterwards.

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The fork top bridge also appears to be damaged, but I think I'd like to switch over to a 360 triple tree and fork tubes, anyways.

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Some bikes just end up with the wrong owners. That poor bike looks to have led a pretty rough life the further you get into it.
 
Some bikes just end up with the wrong owners. That poor bike looks to have led a pretty rough life the further you get into it.

And here's today's installment. The tank looks worse to me outside than inside, but neither is good.

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The PO didn't seem to know how to use the lock tabs on the rear sprocket (36T).

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There is damage to the right side head cover. I'm glad it's not an integrated part of the head.

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One of the center stand brackets is bent.

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And I don't know *what* happened to produce this damage.

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On the plus side, the carbs are cleaning up okay. The bowls have substantial corrosion and the overflow tubes appear to be cracked - hopefully I can seal them up with solder.

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That brake pedal and rod look rough. Pedal looks to have been bent in a right side crash, but explaining the bent rod is a more difficult guess. If there was rear brake backing plate damage or evidence that the torque strap bolt came loose at one point then the rod could have gotten bent when the backing plate rotated but who knows for sure? You should be able to pick up a used right cam bearing/head cover, here's one on eBay that looks okay

https://www.ebay.com/itm/2752803250...D%3D|ampid:PL_CLK|clp:2047675&epid=1611832243
 
For some reason, 'reply with quote' didn't seem to work just now. Thanks for the eBay link, Tom. It's good to know these covers are not yet unobtanium.

I have a good rapport with the owner of the local motorcycle salvage and I'm hoping I can go up there with a list at some point this summer and make a bundle deal. They've been pretty fair with me so far. Originally I was thinking of buying a parts bike from them, but I'm also considering some mix and match, e.g., 360 forks and triple tree. I prefer the forks with the internal springs - I guess those already appear on the later 350s?
 
Once the 350 went to the clamp-type top bridge the fork springs are internal, but the other advantage of the 360 forks is chromed tubes all the way to the top.
 
The step/peg bar is also damaged. I will need a replacement step bar before the frame can be repaired. The mounting box on the right side is intact, so, after cleaning up the frame, my basic plan for a repair would be: (1) rig up a small plate for the left side that has a nut welded into it, (2) bolt the plate onto the step bar, (3) mount the step bar to the bike using the right side bolts, (4) put the left side of the step bar in position to tack weld the plate to the frame, (5) remove step bar and weld the plate securely to the frame.

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Guess what's laying on a shelf in the garage, all clean and PC'd, looking for a good home? PM your address and I'll get it out to you BUT it'll be a few days before that can happen since my daughter tested positive Friday and I have to quarantine. No one else has tested positive yet or have any symptoms.
 
Guess what's laying on a shelf in the garage, all clean and PC'd, looking for a good home? PM your address and I'll get it out to you BUT it'll be a few days before that can happen since my daughter tested positive Friday and I have to quarantine. No one else has tested positive yet or have any symptoms.

Thanks, Jim! I hope you'll allow me to pay something for the part in addition to shipping.
 
In the spirit of getting way ahead of oneself, I am thinking about a starter plug for this CB350. I found a Cappellini plug on eBay. Are there other options?

I have the Common Motor Plug for my 450. My only complaint is that it's a brass-ish color, which doesn't blend in very well.
 
In the spirit of getting way ahead of oneself, I am thinking about a starter plug for this CB350. I found a Cappellini plug on eBay. Are there other options?

I have the Common Motor Plug for my 450. My only complaint is that it's a brass-ish color, which doesn't blend in very well.

The CMC "plug" is nothing but an auto parts store universal freeze plug, not sure I'd ever trust one to stand up properly under exposure to oil but not too much would get up in that corner anyway, and yes they do not look the part at all. AND they're overpriced, compare at the auto parts stores, you can get one for $5 to $6.

I bought one from SpeedMotoCo and it wasn't cheap ($34.95 when I bought it for my 450 in 2017) but it fits well, has an o-ring groove with o-ring and a center "shaft" machined into it that fits in the boss in the cover where the starter shaft would line up (that keep the slip-on starter sprocket from coming off the shaft) so it isn't going anywhere once installed.
 
I bought one from SpeedMotoCo and it wasn't cheap ($34.95 when I bought it for my 450 in 2017) but it fits well, has an o-ring groove with o-ring and a center "shaft" machined into it that fits in the boss in the cover where the starter shaft would line up (that keep the slip-on starter sprocket from coming off the shaft) so it isn't going anywhere once installed.

That looks great. I think my 450 wants one of those, too.
 
That looks great. I think my 450 wants one of those, too.

Full disclosure, the o-ring they sent with it was a tad too fat and it nicked it while putting it in the hole the first time, so I went to the nice o-ring selection box my father left me and found one that fit better but was a tad small so it seeped a tiny bit. I ended up using a little Hondabond around the outer edge in the starter hole after a quick wipe down with a rag with carb cleaner on it (without disassembling) and that took care of it. Still looks much better and you know it isn't going anywhere because of the design.
 
I don't have an engine hanger, so the motor is sitting on a wood frame right now, but I'd like to check the compression. The motor turns over easily by hand and I was thinking of wiring up the starter solenoid and checking compression that way, assuming the starter works.

Does this sound reasonable?
 
Yeah, just make sure the engine is reasonably secure and you can just jump straight to the starter motor terminal. A good pair of jumper cables to a car battery would do it fine, connect the positive to the starter motor post so you don't arc it up at the threads and use the negative end to touch one of the rear motor mounts to complete the ground.
 
I doubt anyone who reads this thread from the start will be surprised by what I discovered today: the exhaust valves seem to be stuck. I tried getting the electric start to turn the motor over to no avail, then found I could easily kick it over. This was confirmed by the 0psi reading on the compression gauge for each cylinder.

I then used my fancy $10 Android borescope to take pictures of the valves, combined below. (Top Left: right intake, Top Right: left intake, Bottom Left: right exhaust, Bottom Right: left exhaust.)

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There was an NGK B8ES plug over the left cylinder and a Champion J8(?) over the right.

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At this point, I'm not sure if I should be rooting for or against the completion of the title paperwork.
 
Well that's ugly, especially the incorrect plug. The PO must have just grabbed whatever he had laying around, like a lawn mower plug... and since the valves were stuck it's possible one or more of them are bent too. Pretty impressive pics for a $10 borescope
 
Well that's ugly, especially the incorrect plug. The PO must have just grabbed whatever he had laying around, like a lawn mower plug... and since the valves were stuck it's possible one or more of them are bent too. Pretty impressive pics for a $10 borescope

The borescope pictures come out as only 640x480, whereas my phone made that collage at 1024x1024. It wasn't as useful in the cylinder for taking a picture, but if the pistons were holed or something major was wrong, I would be able to tell.

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It looks like it takes better pictures than my HF inspection camera which my father bought for me as a Christmas present years back. For a $10 investment I might just snag one of them

Edit: and I've now exceeded my entire post total in almost 4 years at that other forum
 
I doubt anyone who reads this thread from the start will be surprised by what I discovered today: the exhaust valves seem to be stuck. I tried getting the electric start to turn the motor over to no avail, then found I could easily kick it over. This was confirmed by the 0psi reading on the compression gauge for each cylinder.

I then used my fancy $10 Android borescope to take pictures of the valves, combined below. (Top Left: right intake, Top Right: left intake, Bottom Left: right exhaust, Bottom Right: left exhaust.)



There was an NGK B8ES plug over the left cylinder and a Champion J8(?) over the right.



At this point, I'm not sure if I should be rooting for or against the completion of the title paperwork.


I was wondering what other mysteries might be found. This is quite the learning opportunity.

I can see that you are not in a hurry for the title but I see it as a real challenge.

Have you tried the valve adjusters? Maybe spray something on the valve stems and some gentle tapping to see if they'll close.
 
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