1971 CB350 . . . 40 year hibernation

I invested the time to improve the gauge orientation this morning. The M8x16 gauge bracket bolts were upped to M8x25 with a nylon spacer to raise the gauges above the raised section in the middle of the bracket. I just had to make a trip to Home Depot to get the bolts and figure out what kind of spacers were available. There is still a slight rotation outwards, but this seems acceptable.

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I was looking at the photo I posted of the tank previously and learned that the e-clip on the cap hinge had left the building. I replaced it with a 1/8" clip from Home Depot. I bought a pack of two and thought I lost one in the first five seconds. I'm terrible with those small clips.

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I spent about 30 minutes doing these tasks and then decided the yard has been neglected a bit too much recently and spent a couple of hours mowing, pulling weeds, etc.
Nice move on the bracket mounts - I’ve been trying to figure a way to do something similar with the GL and had this elaborate bracket idea in my head. A set of spacers would work as well.

I hear you on those eclips - if I ever move shops, there’s going to be about 200 of those littered underneath rolling cabinets.
 
I hear you on those eclips - if I ever move shops, there’s going to be about 200 of those littered underneath rolling cabinets.
I lose them with such high probability that I may try to come over and harvest some from beneath your rolling cabinets!

I just gambled $20 on a special tool "Ultimate e-clip tool" for 1.5–5mm clips. Hoping it will help.
 
I lose them with such high probability that I may try to come over and harvest some from beneath your rolling cabinets!

I just gambled $20 on a special tool "Ultimate e-clip tool" for 1.5–5mm clips. Hoping it will help.
Have at it! No telling what a magnet fished back there might find.
 
The project has been moving along, but will be on pause until the second week of July. Over the last week or so, I've added the chain, sprocket cover, shift linkage, clutch cable, throttle cable, grips + throttle tube, air boxes, covers, and battery.

I was planning to install CB headers today that I will use for initial tuning and discovered that the used exhaust pipe joints I bought on eBay do not match up with the head. The studs measure roughly 61mm center to center, but the holes on the collar are about 58.5mm center to center. Comparing with a stock photo from CMSNL, the correct parts should have eight fins on top and bottom, but the ones I have only have seven — maybe they belong to a CB175? It's disappointing because they were listed as CB/CL350 parts by the seller.

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I still need to connect the horn and flasher relay to the main harness, add the tank, and install the exhaust, but once I have all the parts it won't take long.
 
E-Clips and Snap Rings( both Inside and Outside) have a Right Side OUT.

They are formed by Stamping which leaves one edge rounded over and the bottom Squared.
If you place the Rounded edge against the Pressure side they can come off.
You need to have the Squared off edge against the Pressure to insure maximum surface area for holding pressure.
 
It's disappointing because they were listed as CB/CL350 parts by the seller.
You know eBay sellers don't always know for sure what they have... even by part number sometimes, and way more often by just description. To be fair, at first glance they do look the same.
 
You know eBay sellers don't always know for sure what they have... even by part number sometimes, and way more often by just description. To be fair, at first glance they do look the same.
True. I've had mostly good experiences with the seller (one of the big ones that we would all recognize), but I should have done more checking when I ordered, or at least when I received the parts. I have had them in my possession for almost a year and took it for granted that they would fit when the time came. That's on me.
 
True. I've had mostly good experiences with the seller (one of the big ones that we would all recognize), but I should have done more checking when I ordered, or at least when I received the parts. I have had them in my possession for almost a year and took it for granted that they would fit when the time came. That's on me.
If you can figure out what they belong to, someone here may well need them and you can at least get some of your money back.
 
The project has been moving along, but will be on pause until the second week of July. Over the last week or so, I've added the chain, sprocket cover, shift linkage, clutch cable, throttle cable, grips + throttle tube, air boxes, covers, and battery.

I was planning to install CB headers today that I will use for initial tuning and discovered that the used exhaust pipe joints I bought on eBay do not match up with the head. The studs measure roughly 61mm center to center, but the holes on the collar are about 58.5mm center to center. Comparing with a stock photo from CMSNL, the correct parts should have eight fins on top and bottom, but the ones I have only have seven — maybe they belong to a CB175? It's disappointing because they were listed as CB/CL350 parts by the seller.

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I still need to connect the horn and flasher relay to the main harness, add the tank, and install the exhaust, but once I have all the parts it won't take long.
Right number fins and bolt center spacing for a 305. Let me look, I think I may have an extra 350 set, because I later welded a cracked set that got replaced on Charles 350.
 
Right number fins and bolt center spacing for a 305. Let me look, I think I may have an extra 350 set, because I later welded a cracked set that got replaced on Charles 350.
Thanks, Tom. I'm glad to see you with some shop bandwidth!

I tried to do a little eBay sleuthing and, based on one photo of 305 joints with a ruler in the background, I think my mystery pipe joints are too small for the 305's. My current guess is that the mystery parts could fit a variety of 175's, 350F/400F, and 550 models that seem to share this part.

I ordered and received used replacements for the 350T, but am currently out of town, which is why the project is on pause for the next week. So, please don't go to any trouble scrounging around for your spares, although the thought is very much appreciated!
 
Thanks, Tom. I'm glad to see you with some shop bandwidth!

I tried to do a little eBay sleuthing and, based on one photo of 305 joints with a ruler in the background, I think my mystery pipe joints are too small for the 305's. My current guess is that the mystery parts could fit a variety of 175's, 350F/400F, and 550 models that seem to share this part.

I ordered and received used replacements for the 350T, but am currently out of town, which is why the project is on pause for the next week. So, please don't go to any trouble scrounging around for your spares, although the thought is very much appreciated!
I'm pretty sure those are 305's because I did measure the bolt centers on my Dream and they are 56.5 ish. Glad you found some 350 flanges. I'd love to find something to contribute to your project.
 
I'm pretty sure those are 305's because I did measure the bolt centers on my Dream and they are 56.5 ish.
I had some extra information when ruling out the 305's that I hadn't shared previously for lack of the right picture. The mystery joints have a recess on the back side that the 305 joints don't seem to possess. My best guess is still the common joints used on 175's, 350F/400F, and 550 models.

mystery joints:
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eBay picture of CB77 joints:
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I'd love to find something to contribute to your project.
I would be hard pressed to identify any current VHT project that is lacking a contribution from the @ballbearian. Among many other things along the way, I really appreciate the moniker Silver Surfer that you applied to this project.
 
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I returned from a trip earlier this week and got back to work on the project. I finished wiring the horn and flasher relay, which allowed me to install the tank and fuel lines.

I also received the 350T exhaust joints (collars) along with a variety of fasteners. I had intended to use a CB exhaust initially, but have not sourced CB headers. I did order an aftermarket set from Thailand, but found they are not a direct replacement and then decided to install the CL exhaust straightaway. This led to two [related] issues.
  1. The lower exhaust bracket that mounts at the swingarm does not fit between the CB side covers and the exhaust.
  2. The clearance between the upper exhaust and the left side cover is essentially zero. I want to correct this before I attempt to start the bike – I don't want to melt the cover.
At least it looks like a complete motorcycle now, although there are still a few other little things to be done.

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Looks good!
Yes, you'll need a CL cover to go behind those pipes. It has a "dent" molded in to clear the exhaust.
Wow – I never realized that! I guess the left side cover was always covered by the exhaust in pictures and I never looked closely at the related sections of the parts fiche. Thank you!

Is there any consensus on the aftermarket covers out of Minnesota?

 
I would have mentioned it but I actually thought you knew already. Yes, special shape of the CL left cover because of the pipes.
Is there any consensus on the aftermarket covers out of Minnesota?
I'm sure you'd rather get them directly from the (likely) source, because they look the same as the ones sold by RetroCB. Scroll the page to see the CL left sidecover

 
I would have mentioned it but I actually thought you knew already. Yes, special shape of the CL left cover because of the pipes.
I appreciate the benefit of the doubt even if I didn't deserve it. I should've figured this out a year or more ago, but it never occurred to me that the covers would be different.
 
Wow – I never realized that! I guess the left side cover was always covered by the exhaust in pictures and I never looked closely at the related sections of the parts fiche. Thank you!

Is there any consensus on the aftermarket covers out of Minnesota?


I bought plastic things this seller had made for a Honda CH250 scooter, a few years ago. Those were very good. He was slow to get things out to be delivered, but a very decent seller of decent things. If you look at the other items from this seller you'll see that he seems to have access to scanning and reproducing plastic parts.
 
I bought plastic things this seller had made for a Honda CH250 scooter, a few years ago. Those were very good. He was slow to get things out to be delivered, but a very decent seller of decent things.
Thanks for the report, Bob. Jim has generously donated one of his spare covers to the cause, but this is good info for the future.
 
I really like the reversal of the light and dark areas with the paint, it makes the structure of the 350 stand out in a different way, yet still seems true to it's vintage look.

eBay picture of CB77 joints:
I only really know the CA77 versions of the 305 but mine aren't like these ebay ones and use the split collars with the recessed groove for them on the backside.
 
I really like the reversal of the light and dark areas with the paint, it makes the structure of the 350 stand out in a different way, yet still seems true to it's vintage look.
It combines features of all three of 350 models in one bike.
Yep, it's kinda like an SL350K0 with black CL exhaust and oversized CB gas tank for more fire road range.

Thanks, all. Honestly, there's a lot of similarity to the story told in the song 'One Piece at a Time' written by Wayne Kemp and made famous by Johnny Cash and the Tennessee Three. I identify with the lyric: "I'll have the only one there is around." I really liked and was definitely influenced by the SL450 project that was shared and discussed on the forum (here) a while back as well as Richard's SL175 look alike project (here), but I allowed the inherited and readily obtainable parts to dictate the direction the project went.
 
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Well... I started the bike this morning. I don't think it went super well and I will try to lay everything out to see what my next step(s) should be.

It took several kicks to get to a point where I heard some popping sounds of ignition and from there it took two or three more kicks and a small amount of throttle to keep the motor running. There was an unfamiliar clanking sound that seemed to emanate from the high pipes — I had the impression that one of the heat shields was rattling. The thought also crossed my mind that something could be rusted out inside one of the mufflers and clanking around with each cycle of the motor. I put my left hand on the long heat shield in the front and the noise seemed quieter, so I shut down the motor and checked the bolts on all three heat shields. I found a few that were loose enough to allow unwanted vibration of the shields and tightened them. (Side note: I think the threads were a little tight after the shop painted the exhaust and I had tightened everything gently during installation. I should have cleaned the threads with a tap first.) I then started the bike again (first or second kick, I think) and was surprised to still hear the clanking sound. I shut it off and removed the long heat shield. Started it and still heard the sound. I felt the pressure at the end of the pipes, but my memory is conflicted here. One of the pipes had more pressure, but I'm not 100% sure which. I would say 60/40 it was the right (upper) pipe. Shut it off. The pipes were warm at this point, but not so hot that I couldn't rest my hand on them. I would guess that the motor ran for a total of less than two minutes, maybe less than one minute. I didn't record any video (or audio) while the motor was running.

My next step was to remove the alternator cover and turn the motor over by hand. I found that there is an substantial click occurring inside the motor at two points in the cam cycle. The "first" click occurs as the full advance mark nears the timing mark for the right cylinder. At this point, only the left exhaust valve is closed. The "second" click occurs 180° later on the crank, which I believe is the compression stroke on the left cylinder. Again, the click is heard just as the full advance mark reaches the timing mark. At this point only the right intake valve is open. The next two 180° turns on the crank are quiet and then the whole thing repeats.



At this point, I began worrying about valve guides slipping, but thought the cam chain tensioner might also be a possible culprit. I turned the crank to 90° after TDC on the left compression stroke and reset the cam chain tensioner. I didn't hear the distinctive pop when the bolt was loosened, so I figured the plunger was either stuck or already adjusted properly. I went back to the crank and nothing had changed. I decided to turn the crank back around to 90° after TDC on the left compression stroke and removed the tensioner. I was surprised to find that the plunger was still recessed slightly in the casing, yet the roller body was also slightly recessed in the cylinder when gently held against the chain. When I released tension on the holder bolt, the plunger sprung out as expected.

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I thought maybe the tensioner was the source of the noise and the last thing I did was turn the motor over slowly with the tensioner removed. The same two clicks occur at the same two points in the cycle. I don't recall hearing these noises when I set the valves and timing, but that was quite a while ago at this point. I'm mentally preparing myself to pull the motor, but thought I should pause and gather thoughts here. Thanks in advance for any advice.
 
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My first thought was that the timing between the crank shaft and the cam is one link off, and you're hearing a piston hitting the edge of a valve. Your experiences with the tensioner sort of support the idea, and turning the engine without the tensioner in place makes the situation even more suspicious. I've had a similar experience with a CB450 and it took some careful work to synchronize everything. Maybe someone with 350 experience can give you some guidance.
 
Oh Bother! I would use stronger language but not in open forum, so darn close. I was thinking cam chain timing off as well but hate to say it out loud, If it is hopefully no damage has been done.
 
I'm wondering if the snap noise is the cam jumping forward as a valve closes because the tensioner hadn't correctly tensioned the chain. If you watch the advancer during rotation you'd be able to tell. Or, and this would be worse, one of the cam sprocket bolts is cracked or broken and the sprocket is moving during rotation. Or maybe, though I've never personally head what one sounds like, a cracked valve spring?

Oh, and I'd be very cautious turning the engine without the tensioner.
 
Thanks for the ideas so far. I documented the cam timing here and it looks okay to me, but I guess it's possible it jumped if the tensioner wasn't properly set. I suppose it's also possible that I didn't account for the timing mark on the Rick's stator properly, but I did mark the cover using the original stator before installing the replacement.

The ticks both occur just before the full advance mark passes the timing mark, which is roughly 30° before TDC. I would expect that should eliminate piston and valve contact, especially since one tick is on the left compression stroke with both valves closed on that cylinder. I can remove the plugs and watch/listen for contact, so I will do this tomorrow.

I'm wondering if the snap noise is the cam jumping forward as a valve closes because the tensioner hadn't correctly tensioned the chain. If you watch the advancer during rotation you'd be able to tell.
I'd like to do any conceivable diagnostic tests before pulling the motor, so this is a great suggestion. I'll try to see if there is a corresponding jump of the advancer. I suppose I could also watch the chain since the tensioner is currently off. I'll hold off on reinstalling the tensioner until after trying the above.

Crossing my fingers that the sprocket/bolts and valve/springs are okay, but I suppose I could pull out my cheapo endoscope to look at the valve springs.

I'd be very cautious turning the engine without the tensioner.
For sure. I'm turning very slowly in small increments and by hand, of course.
 
Crisis hopefully averted... it seems that the noise was coming from the cam chain due to incorrect tensioner installation. Repeating a picture from above, notice that I held the tensioner in place with a wrench to show its position when it meets the chain. My mistake was allowing the cam tensioner to fall outwards when installing the holder and the tensioner was apparently ending up below the plunger (push bar). So, when I released the holder bolt, nothing could move.

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The suggestion from @ancientdad really helped me narrow it down. The two snaps coincided with moments when the cam would roll/jump forward on its own, which I was able to observe by watching the advancer bolt. I looked in the sparkplug holes after each snap and did not see anything untowards happening inside. The piston tops are very clean still with the machinists Sharpie marks for orientation and cylinder. At that point, I reinstalled the tensioner and, again, failed to hear any movement when I released the holder bolt. The snaps were still present, so I removed the tensioner holder again with a suspicion that the tensioner was wedged under the plunger. That turned out to be the case and I was very careful to avoid that when reinstalling the holder for the third time. I then turned the motor over a couple more times and the snapping sounds were gone.

I had read in the manual yesterday that a loose cam chain will cause excessive engine noise (see excerpt below), but I doubt that it would be as excessive as what I was hearing in this case. It's too bad I didn't record it, but I suppose I could do without ever hearing it again. I don't like to push my luck too much and it's going to be a hot day, so I will wait to start it again on another day.

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That was one thing I didn't anticipate, but I can absolutely see how it could happen. Glad you figured it out, and even more glad nothing bad happened along the way. With that much slack in the cam chain, I'm amazed it didn't do something ugly while running initially.
 
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That was one thing I didn't anticipate, but I can absolutely see how it could happen. Glad you figured it out, and even more glad nothing bad happened along the way. with that much slack in the cam chain, I'm amazed it didn't do something ugly while running initially.
I hesitate to criticize the design, but I found it a bit awkward to install the holder and make sure the push bar engaged the tensioner. My mistake was assuming everything would automatically line up as I installed the holder.

I checked one valve clearance yesterday as part of my diagnostic work, but I think I should probably recheck clearances and timing before starting.
 
The goal for this morning was to restart the motor. The first order of business was to make sure that the cam timing had not been altered due to the tensioner shenanigans. I removed the left spark plug and rotor cover and turned the motor around to the TL mark, carefully watching the piston rise with a flashlight. The cam timing checked out, so I decided to trust my earlier valve adjustments, having verified one the day before and having confirmed that each valve was "loose" when it was supposed to be during diagnostic work over the last two days. I moved on to timing and found the left cylinder to have slightly retarded timing, which I then corrected. I moved on to the right cylinder, which also had retarded timing. I believe I may be using the same brand (or non-brand as it were) of points that @Violet is using on her SL350. I barely managed to achieve acceptable timing and point gap with the adjustment range they have. If timing becomes an issue at any point, I will upgrade.

The motor started up and sounded okay. I didn't run it much longer than the video below shows. The next step will involve fine-tuning the clutch adjustment as well as both drum brakes for a first test ride. Maybe tomorrow.


Oh. And I guess I need to oil or otherwise improve the function of the tach.
 
Sounds pretty good, though the off-idle response seems a bit flat but it could have just been because it wasn't fully warmed up. Glad there were no ill effects from the tensioner snafu. I'm sure you already ruled out the cable causing the tach issues, looks more like it needs internal lubing.
 
You're in that moment when everything says test run, but somehow you know you could have forgotten a critical thing that will bring down the house of cards.

That's when I take a very slow ride up and down the road, maybe into second gear, and stop a lot to test the brakes. We'll get to higher rpms soon enough.
 
That's when I take a very slow ride up and down the road, maybe into second gear, and stop a lot to test the brakes. We'll get to higher rpms soon enough.
I am fairly conservative when putting a rebuilt bike back on the road. I have a salvage title, but no registration, so I'll just be going up and down a block or two for the time being. The speed limit is 30 mph. If I get really crazy, I may circumnavigate the block. The goal will be to work out bugs in preparation for a state inspection to convert the salvage title to a standard title for registration purposes.
 
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