• Don't overlook our Welcome Package, it contains many links to important and helpful information about functions at VHT like posting pictures and sending PMs (private messages), as well as finding the parts you need.

    AD

Barn Find Frankenbike - 1968 CB350

Abinaz

Member
Joined
Dec 26, 2022
Total Posts
48
Total likes
30
Location
Clarkdale, AZ, USA
Greetings. Inherited from an old friend this 1968 CB350 that has sat in a barn since 199. It is a bit of a mash-up with parts from multiple years and lots of random or missing fasteners, wiring modifications, and missing/broken parts. I don’t aspire to a full restoration, rather this will be a learning experience with hopefully a cool, old, running, and safe machine to show for it. I’ve posted a couple times regarding this bike but thought it would be good to start a thread wherein everything will be in one place.

4415ED80-E9CF-489C-B4AF-B541D9FC0BC9.jpeg

I have original factory manuals in hand and hopefully you guys watching over my shoulder so here we go!

The engine has good compression, and favorable leak-down results so should run okay. I am planning to rebuild the cam chain tensioner per everything I’ve read on this forum. Not sure yet what else I will do to the motor while I have it out, other than to replace the broken kick start spindle.

I started with carb rebuilds, which I consider the low hanging fruit on this project. They were tragically dirty and gummed up but with some quality time in the ultrasonic cleaner and a rebuild kit they are on the shelf awaiting the day the bike gets reassembled.

What I know so far is a piece is broken off the kick-start spindle allowing the kick-start arm to flop forward to the rear brake pedal, the electric starter does not run, the starter clutch outer ring is broken (per my post from yesterday).
image.jpg
59F12F79-0DEC-4972-A2AB-451DFFBA4F69.jpeg

The PO reported the charging system was not working. I pulled the stator coil today and it appears it is completely shorted with close to zero resistance across the yellow, white, and pink wires. Hmm, could explain why the bike would not charge.

This’ll be interesting! More later…..
 
I'll be curious to see if it's the kickstart shaft that's broken, or the stop on the crankcase.

Also, you may not be aware that carb rebuild kits cannot be trusted to have correctly sized jets and other hard parts, so hopefully you didn't toss that jets and other parts you removed form them. They should be cleaned and re-used whenever possible, as kits' components can't be trusted.
 
When I drained the oil, a small broken piece of steel fell out:
image.jpg
Someone suggested it was from the kick-start spindle and I figured that could explain the forward rotation of the kick-start arm. Any other ideas?

And yes, I’ve kept all the original carb parts!
 
Well it certainly looks like it could be from the kickstart shaft, but it's rare that aluminum wins over steel which is why I wondered. I'd suggest starting with the right crankcase cover to see what you see there before pulling the engine to go into the bottom end. And good for you that you saved the original jets. (y)
 
Good suggestion, thank you. I figured I needed to pull the engine anyway to replace the rubber cam chain tensioner wheel. Do you have other thought about that?
 
Good suggestion, thank you. I figured I needed to pull the engine anyway to replace the rubber cam chain tensioner wheel. Do you have other thought about that?
Yes, I wasn't sure if you meant just the tensioner assembly itself, which is on the back of the cylinders, but since you need to go into the top end then pulling the engine is the only option. And since you plan to do that, you may as well wait until the engine is out (oil drained first, of course) to pull the clutch side and take a look.
 
Yeah, that'll be fun to get running. At least it looks like it's all there.
From all the hex head screws looks like someone's been in that engine before.
Is it the original engine?
 
Unfortunately I really don't know the history of the bike in terms of whether or not the engine has been worked on. But all signs indicate that someone has messed around with it quite a bit as evidenced by all the mangled and/or replaced fasteners, missing washers, swapped out parts, wiring modifications, etc. I do know the engine has good compression and leak-down, so I don't plan to do any more to it than to replace the cam chain tensioner and see what's going on with the floppy kick-start spindle; at least that's the thought process thus far.
 
Why is the the non-hydraulic tensioner preferred and when did they switch? I assume the non-hydraulic cam chain tensioner would be a simple swap out for the original.
 
Why is the the non-hydraulic tensioner preferred and when did they switch? I assume the non-hydraulic cam chain tensioner would be a simple swap out for the original.
It is a simple swap for the later version, and IIRC the reason was the hydraulic version was not very effective at lower rpm. The switch was early, from engine number 1079079 forward.
 
Why is the the non-hydraulic tensioner preferred and when did they switch? I assume the non-hydraulic cam chain tensioner would be a simple swap out for the original.
In theory, it worked the same way as a hydraulic lifter, a plunger behind the tensioner arm with oil behind it. Movement in the tensioner arm ,from slack in the chin, would allow the plunger to advance to take up the slack. Trouble was, the oil could sometimes drain back into the sump at night and when it was started the the next time the cam chain would be loose until enough oil had worked its way up there to displace the air behind the plunger. If I remember correctly, one of Honda's first attempts to solve the issue was to replace the bleeder bolt on the top of the housing with one having a tiny hole in it, to continually bleed any any trapped air behind the plunger as the engine ran, probably not the best solution since it robbed oil from that small trickle of oil that fed the top end.
 
Greetings. Inherited from an old friend this 1968 CB350 that has sat in a barn since 199. It is a bit of a mash-up with parts from multiple years and lots of random or missing fasteners, wiring modifications, and missing/broken parts. I don’t aspire to a full restoration, rather this will be a learning experience with hopefully a cool, old, running, and safe machine to show for it. I’ve posted a couple times regarding this bike but thought it would be good to start a thread wherein everything will be in one place.

View attachment 26354

I have original factory manuals in hand and hopefully you guys watching over my shoulder so here we go!

The engine has good compression, and favorable leak-down results so should run okay. I am planning to rebuild the cam chain tensioner per everything I’ve read on this forum. Not sure yet what else I will do to the motor while I have it out, other than to replace the broken kick start spindle.

I started with carb rebuilds, which I consider the low hanging fruit on this project. They were tragically dirty and gummed up but with some quality time in the ultrasonic cleaner and a rebuild kit they are on the shelf awaiting the day the bike gets reassembled.

What I know so far is a piece is broken off the kick-start spindle allowing the kick-start arm to flop forward to the rear brake pedal, the electric starter does not run, the starter clutch outer ring is broken (per my post from yesterday).
View attachment 26356
View attachment 26355

The PO reported the charging system was not working. I pulled the stator coil today and it appears it is completely shorted with close to zero resistance across the yellow, white, and pink wires. Hmm, could explain why the bike would not charge.

This’ll be interesting! More later…..

How is it possible to mount the timing cover like that? Please rectify immediately my OCD is kicking in :)
 
I think I figured it out. The stator mounting screws are not installed in the correct positions.
 
Last edited:
How is it possible to mount the timing cover like that? Please rectify immediately my OCD is kicking in :)
Yes it’s rather nutty. A PO had apparently pulled the stator and upon re-fastening it opted to use only one screw and that screw was in the threaded hole at the 12:00 position, precluding proper orientation of the cover which normally uses that hole. Like a lot of things on this bike, I don’t understand why things were done the way they were.
 
When I drained the oil, a small broken piece of steel fell out:
View attachment 26357
Someone suggested it was from the kick-start spindle and I figured that could explain the forward rotation of the kick-start arm. Any other ideas?

And yes, I’ve kept all the original carb parts!
Early CB350s had some kickstarter issues, the early design didn't work too well. Hopefully, that's all that's broke, We had to replace the crankcase halves on a few of them back then.
 
Upon pulling the clutch side cover, I confirmed that the small lug to which the spring is clipped on the kickstart spindle was indeed broken off so for sure kickstart spindle replacement is on the to do list.

I had planned to split the case to replace the cam chain tensioner rollers based on multiple recommendations to do so here on VHT, but I had no way of knowing whether or not they had already been replaced. To be sure, a PO had replaced the cross-slot screws with hex bolts hinting that at least some engine work had been done and I hated the thought of tearing apart an engine that didn't need to be torn apart. But I lucked out I guess you could say. Upon inspection of the oil screen, I found many chunks of rubber that almost certainly came from the cam chain tensioner rollers. Here is a sampling:IMG_3427.JPG
So now I have at least a couple reasons to take this engine apart! The motor is now sitting on the workbench and I will be slowly and carefully dismantling it and assessing condition as I go. Will keep you posted!
 
Monday update. Top end is removed and an interesting finding is that a PO did in fact replace the cam chain tensioner rollers as they are intact, so the rubber roller chunks I pulled out of the oil strainer (see previous post) must have been from a since-replaced set of rollers.
72204398529__7CDC8716-AB88-4A91-882C-AA80A0693126.JPG
IMG_3483.JPG
IMG_3484.JPG
 
Interesting... Champion plugs, battery bolts used to hold the points plate, and both valve springs on the right cylinder are upside down along with that ugly looking right piston. These poor engines suffer so much more at the hands of the lesser informed than we sometimes realize.
 
Your powers of observation are impressive! Can you elaborate as to what's ugly with the right piston? This is the first time I've ever seen a piston so don't know what is normal.
 
It has a lot of galling on it (partial seizure marks), could be from running the engine at high rpm on the road for a long time with a low oil level, or it could be from poor oiling to the crankshaft passages due to gunk buildup caused by poor maintenance over the years (there's a recent, very involved discussion about crankshaft cleaning going on right now). Here's what used pistons in serviceable condition should look like.

20161016_173616.jpg
 
It has a lot of galling on it (partial seizure marks), could be from running the engine at high rpm on the road for a long time with a low oil level, or it could be from poor oiling to the crankshaft passages due to gunk buildup caused by poor maintenance over the years (there's a recent, very involved discussion about crankshaft cleaning going on right now). Here's what used pistons in serviceable condition should look like.

View attachment 27006
Thanks. Do you recommend I replace the pistons?
 
Thanks. Do you recommend I replace the pistons?
Just based on seeing that one piston that is fully exposed to view, absolutely. You'll need to take the cylinders and head to a good machinist to have measured and inspected so you'll know what size of oversized pistons to buy and whether or not the head will need the valve seats cut and the valve guides replaced.
 
It has a lot of galling on it (partial seizure marks), could be from running the engine at high rpm on the road for a long time with a low oil level, or it could be from poor oiling to the crankshaft passages due to gunk buildup caused by poor maintenance over the years (there's a recent, very involved discussion about crankshaft cleaning going on right now). Here's what used pistons in serviceable condition should look like.

View attachment 27006
Thanks. Do you recommend I replace the pistons?
 
Thanks. Do you recommend I replace the pistons?
I guess you missed this (below) in my reply above.

Thanks. Do you recommend I replace the pistons?
Just based on seeing that one piston that is fully exposed to view, absolutely. You'll need to take the cylinders and head to a good machinist to have measured and inspected so you'll know what size of oversized pistons to buy and whether or not the head will need the valve seats cut and the valve guides replaced.
 
I guess you missed this (below) in my reply above.


Just based on seeing that one piston that is fully exposed to view, absolutely. You'll need to take the cylinders and head to a good machinist to have measured and inspected so you'll know what size of oversized pistons to buy and whether or not the head will need the valve seats cut and the valve guides replaced.
Thanks. Do you or any other member have recommendations for a shop that does quality cylinder/head work? I’m in Northern Arizona where resources are limited so expect I’ll need to ship my engine components somewhere for work.
 
I'd suggest Chris Schumann for the head work - https://www.facebook.com/p/Schumann-Motor-Works-100054197273586/

Can't speak to getting the cylinders bored, Jim (LDR) may have a recommendation
Plus 1 on having Chris do the head.
You're located out in the pucker brush of AZ so finding a local solution for the cylinders is questionable. Looks like a possibility at Flagstaff Engine and Machine but they may not be equipped for the small bore of a 350 which is the 1st question to ask any shop. PHX may have better options but that's a 2 hour drive at least for you.
I used Tom's Performance here in Vancouver https://tomsperformancemachine.com/ so that would be an option for shipping the Cylinder and pistons to.
A machine shop that does VW air cooled engines on a regular basis is something to explore.
 
Belated Happy Thanksgiving everyone and thanks for the suggestions on machine shops. I reached out to Mike Nixon at motorcycleproject.com and he offers cylinder boring service as well as head reconditioning. He is only an hour away so next week I plan to drive over the hill to Prescott, AZ to talk with him and check out his machine shop. He is very approachable, pricing seems very competitive with other more distant options, the convenience is compelling, he definitely seems to know what he is doing, and his turn-around time is about 3-4 weeks. All good in my book!

In the meantime, I am thankful I was able to split the crankcase this morning and get at the busted kickstart spindle you've heard me going on about.
IMG_3501.JPG
IMG_3507.JPG
IMG_3508.JPG
IMG_3509.JPG
Found lots of sludge and more chunks of past cam-chain tensioner rollers.

And here is the broken kick-start spindle:
IMG_3510.JPG
I understand this (above) is the original design for the kickstart assembly and that the newer ones look like this (below, image found online):
IMG_3506.JPG
So the question for any experts out there is: Would the newer version work in my 1968 crankcase?
 
I dunno about that, but seems splines are always getting wrecked, so if you found a cheap one with bad splines and a good collar, maybe make a good one from that and yours.
 
Happy New Year everyone. The '68 is now stripped down to the bare frame. Head and cylinders are sent off and awaiting machining. Time to focus on getting the frame sorted. I've got a powder coating option nearby and will be going that route, but first there is a repair to the foot rest bar brackets on the frame that will need to be taken care of. The parts diagram seems to indicate the four bolts that hold the foot rest bar onto the frame get screwed into threaded brackets welded onto the frame. In my case, there were loose nuts and washers inside the little mounting brackets which just had clearance holes for the 8mm bolts.
IMG_3662.JPG
IMG_3663.JPG
IMG_3664.JPGIMG_3665.JPG
As you can see, the brackets are a mess. And getting the foot rest bar off without being able to get a wrench on the loose nuts was a *****, and reassembly might be even harder. I've got access to a skilled and well equipped welder so that will help. But I wonder if any of you have seen this kind of mess before and if you have any recommendations on the best way to repair these mounting points. I'm thinking some kind of nut plate could be tacked on to the backside of the existing damaged brackets, or perhaps the mounts should be cut off and new mounts fabricated and welded on. Any thoughts and ideas would be more than welcome. Thanks!
 
I think I figured it out. The stator mounting screws are not installed in the correct positions.
I just got to the bottom of the rotated alternator cover issue that was giving Ausman1000 OCD fits. I've been focusing on other things like getting the frame and other parts prepped for powder coating and cleaning up engine parts and just got to the crankcase left side cover where I discovered that two of the six threaded mounting bosses inside the cover (three for the stator, three for the alternator cover) were broken off! Has anyone seen this before or have any thoughts as to how this could happen? Guess I'll be looking for a new side cover.IMG_3743.JPG

72774963391__DC8E1315-C51E-4874-9FE1-059B8310B31C.JPG
72774965849__1F884524-06E1-4BC7-B1D4-7CCD4BF0E6A0.JPG
 
I just got to the bottom of the rotated alternator cover issue that was giving Ausman1000 OCD fits. I've been focusing on other things like getting the frame and other parts prepped for powder coating and cleaning up engine parts and just got to the crankcase left side cover where I discovered that two of the six threaded mounting bosses inside the cover (three for the stator, three for the alternator cover) were broken off! Has anyone seen this before or have any thoughts as to how this could happen? Guess I'll be looking for a new side cover.View attachment 28873

View attachment 28874
View attachment 28875
Yes, fascinating indeed :rolleyes:

Big thank you to Abinaz for putting my OCD fits to rest today?? :rolleyes:

Last time I bother to comment on your thread.

Is there a negative like button somewhere?
 
Last edited:
A public apology to ausman1000 for my comment re: OCD fits. That was insensitive of me. I should rather have commented on ausman1000's astute observation of a rotated alternator cover from a marginal photograph. Cheers.
 
A public apology to ausman1000 for my comment re: OCD fits. That was insensitive of me. I should rather have commented on ausman1000's astute observation of a rotated alternator cover from a marginal photograph. Cheers.
All is good. I came home from work a little grumpy last night and over reacted. Carry on with an interesting thread.
 
The latest unfortunate discovery is that the seat pan is absolutely toast! The seat definitely needed new foam and cover as original foam had partially turned to dust and the cover was ripped. Upon removing these, I discovered the seat pan was badly rusted and had ben taco-ed somehow:IMG_3788.JPGIMG_3789.JPGIMG_3790.JPG
 
Good news is my welder did a good job fixing the messed up footrest bar brackets and the frame and associated black bits are now at the powder coater:
IMG_3791.JPGIMG_3792.JPG

I also took the tank over to the powder coater to to see about getting it sandblasted and we brainstormed how to reproduce the original two-tone paint job. For a very reasonable price, he would sandblast and base coat the entire tank so that all I would need to do is mask and paint the other color. I am thinking of base coating the entire tank white, then I would only have to paint the top half of the tank blue. Is there any reason why this approach might not work? And a related question, for the original two tone blue and white paint scheme, I assume the entire underside of the tank was white? Can anyone confirm this? And finally does anyone have a paint code for the 1968 blue color?

Other updates, I had Mike Nixon rebuild the head as the valves were receded and the guides were loose. Also the head was bored .25 over and we found NOS Honda oversize pistons. I really enjoyed working with Mike as he is another wealth of knowledge and conveniently only an hour away. So now I can begin engine reassembly!
 
Good news is my welder did a good job fixing the messed up footrest bar brackets and the frame and associated black bits are now at the powder coater:
Looks good. VHT member @ballbearian just went through the same process on a frame that was bent a bit in the area as well.

 
The latest unfortunate discovery is that the seat pan is absolutely toast! The seat definitely needed new foam and cover as original foam had partially turned to dust and the cover was ripped. Upon removing these, I discovered the seat pan was badly rusted and had ben taco-ed somehow:
Those are typical stress fractures and an excellent candidate for repair, IMO. Jeez, that's just surface rust. Reinforce and weld.
Nice welds on the frame, by the way.
 
Good idea. I'll take the seat pan over to the welder and see what he thinks. I've been electrolytically de-rusting the tank in a big plastic bin and I think the seat pan will fit in there. You might have just saved me some money so thank you for the suggestion!
 
Back
Top Bottom