Are the frames a weak spot on these bikes? Buying a bike, better check the frame

[jeepnjohn]

I have in the last 6 months purchased 4 cl350s and 1 cb 350 (5 total) Two were designated to be projects and the others are parts bikes to support these projects. Thus far, I have stripped down 3 of these bikes and found all of these frames to have rusted holes or kinda rusted cracks in the lower portion of the frame between the front motor mounts and ahead of the foot peg cross bar mounts.

While a couple of these bikes have had a hard life, the ones I chose for projects were kept inside and looked to be like decent restoration projects.

Furthermore, I know of other bikes that were advertised that the sellers came right out and stated the frames were broken/junk.

Not sure what I am going to find on my remaining two frames.

One of the three frames above was going to be one of my projects as it was a titled bike. Projects sort of on hold till I get this sorted and determine how to proceed. The holes on this one dont look to bad and I am thinking about getting it welded up, but I need to look a little closer and ream the holes out to evaluate how weak or bad it could be. Now to me, it looks like the engine provides some structural support in this area but I want the bike to be 1) structurally sound, and 2 look good.


For all of you with loads of experience on these bikes, is this a major issue to be aware of on these bikes?

Based on my sample size, I would certainly be advising anyone who is looking to restore or purchase one of these bikes to look closely at the frame. In order to see this, you are going to have to get down on the ground and look at the underneath of the frame in this area.

 

[ballbearian]

Interesting. I haven't had problems in those areas (yet). Any mouse nests in the headstock?

Mousetown, my own 73 CL350 (vintagehondatwins.com)

 

[bilbikek411]

I have in the last 6 months purchased 4 cl350s and 1 cb 350 (5 total) Two were designated to be projects and the others are parts bikes to support these projects. Thus far, I have stripped down 3 of these bikes and found all of these frames to have rusted holes or kinda rusted cracks in the lower portion of the frame between the front motor mounts and ahead of the foot peg cross bar mounts.

While a couple of these bikes have had a hard life, the ones I chose for projects were kept inside and looked to be like decent restoration projects.

Furthermore, I know of other bikes that were advertised that the sellers came right out and stated the frames were broken/junk.

Not sure what I am going to find on my remaining two frames.

One of the three frames above was going to be one of my projects as it was a titled bike. Projects sort of on hold till I get this sorted and determine how to proceed. The holes on this one dont look to bad and I am thinking about getting it welded up, but I need to look a little closer and ream the holes out to evaluate how weak or bad it could be. Now to me, it looks like the engine provides some structural support in this area but I want the bike to be 1) structurally sound, and 2 look good.


For all of you with loads of experience on these bikes, is this a major issue to be aware of on these bikes?

Based on my sample size, I would certainly be advising anyone who is looking to restore or purchase one of these bikes to look closely at the frame. In order to see this, you are going to have to get down on the ground and look at the underneath of the frame in this area.

I previously hadn't known these 350,etc. frames to rust-out in those areas,until I read Tom's 'mousetown' thread with his CL350 frame.

 

[ancientdad]

I don't know if any of us can be considered more knowledgeable on the aging of these frames because we're basically all in uncharted territory here based on the sheer age of them. As we've said here many times before, I don't think Soichiro Honda ever imagined these bikes would still be around and in high demand 50 years after being built and sold, and regardless the care that was given these bikes over the decades (short of full-time indoor storage), we're talking about simple inexpensive bikes built for the masses at the time. Look how quickly the frames on passenger cars and trucks rust through when exposed to a decade of northern winters with salt on the roads, they don't fare any better. With no way to be sure of where a bike came from and how it was treated previously, it's just a crapshoot when you're buying a 50 year old machine.

 

[jeepnjohn]

Interesting. I haven't had problems in those areas (yet). Any mouse nests in the headstock?

Mousetown, my own 73 CL350 (vintagehondatwins.com)

I saw that post, LOL. No mice nests in these. at least not yet. I live out in the country and the prefer to go into my boats and chew up the air cleaners in my cars.

Once I was getting ready for a fishing trip and had the cover off of my 175 mercury and saw one run down the intake. I left it open all night long thinking he would come out. The next day I went to the boat landing and backed my boat into the lake. Started right up like it normally does, good running motor. WHile idling, I heard it cough a little and then I saw a chewed up mouse come out of the exhaust area of the propeller. Motor seemed to run odd after that. Took it into the marina for a quick check prior to leaving on my fishing trip and they put the boat in their pool, and when they started it, they found about a dime size hole in the block of my engine. Ruined the motor. When I told them the story, they did not believe me. I told them I wouldn't have beleived it either, but I saw it with my own eyes.

 

[ballbearian]

I don't know if any of us can be considered more knowledgeable on the aging of these frames because we're basically all in uncharted territory here based on the sheer age of them. As we've said here many times before, I don't think Soichiro Honda ever imagined these bikes would still be around and in high demand 50 years after being built and sold, and regardless the care that was given these bikes over the decades (short of full-time indoor storage), we're talking about simple inexpensive bikes built for the masses at the time. Look how quickly the frames on passenger cars and trucks rust through when exposed to a decade of northern winters with salt on the roads, they don't fare any better. With no way to be sure of where a bike came from and how it was treated previously, it's just a crapshoot when you're buying a 50 year old machine.

Yes on the unknowns. Stress cracks would be a different concern than damage from elements or impacts. I would like to see pics if possible.

 

[jeepnjohn]

I don't know if any of us can be considered more knowledgeable on the aging of these frames because we're basically all in uncharted territory here based on the sheer age of them. As we've said here many times before, I don't think Soichiro Honda ever imagined these bikes would still be around and in high demand 50 years after being built and sold, and regardless the care that was given these bikes over the decades (short of full-time indoor storage), we're talking about simple inexpensive bikes built for the masses at the time. Look how quickly the frames on passenger cars and trucks rust through when exposed to a decade of northern winters with salt on the roads, they don't fare any better. With no way to be sure of where a bike came from and how it was treated previously, it's just a crapshoot when you're buying a 50 year old machine.

One observation, is that I saw some scrapes on the bottoms of these frames similar to what you might see on an enduro. No I have seen an option for a skid plate, but I have never seen one on a bike, maybe that was not an option in the US. From what I have seen, a skid plate may have helped in this area.

 

[jeepnjohn]

I will get some pictures posted.

 

[ballbearian]

I saw that post, LOL. No mice nests in these. at least not yet. I live out in the country and the prefer to go into my boats and chew up the air cleaners in my cars.

Once I was getting ready for a fishing trip and had the cover off of my 175 mercury and saw one run down the intake. I left it open all night long thinking he would come out. The next day I went to the boat landing and backed my boat into the lake. Started right up like it normally does, good running motor. WHile idling, I heard it cough a little and then I saw a chewed up mouse come out of the exhaust area of the propeller. Motor seemed to run odd after that. Took it into the marina for a quick check prior to leaving on my fishing trip and they put the boat in their pool, and when they started it, they found about a dime size hole in the block of my engine. Ruined the motor. When I told them the story, they did not believe me. I told them I wouldn't have beleived it either, but I saw it with my own eyes.

Wow, reminds me of those karate guys who break cinder blocks with their head.

 

[stl360+450]

My current CB350 project started with a damaged frame that I have decided not to use. Although it was a CB, it was made up as a CL and I suspect that one of the POs abused it on trails. The step bar was mangled and had been welded to the frame on the kickstand side. The center stand was absent and the lower frame tubes were bent slightly, as if they landed on rocks frequently. No skid plate. I suspect that many of these CLs were used that way for the reason that AD mentioned. They were relatively inexpensive and, as we all know around here, are a blast to ride.

 

[Cycleranger]

Living in the south where it's generally drier and they don't salt the roads I haven't had any issues with frame rust on any of the bikes I've purchased. I did have to replace the rims on my CJ360 due to rust but the frame was fine.

I don't think Hondas are any more prone to frame rust than any other bikes from that time period.
They all have drain holes in the bottom of the frame that can get clogged and allow moisture to accumulate.
In the north I know that water freezing in the frame can make the tubes split, as well as rust.

I think it's mostly dependent on where the bike lived its life, how it was ridden, and how it was stored the determines that condition of the frame now.

 

[ballbearian]

My current CB350 project started with a damaged frame that I have decided not to use. Although it was a CB, it was made up as a CL and I suspect that one of the POs abused it on trails. The step bar was mangled and had been welded to the frame on the kickstand side. The center stand was absent and the lower frame tubes were bent slightly, as if they landed on rocks frequently. No skid plate. I suspect that many of these CLs were used that way for the reason that AD mentioned. They were relatively inexpensive and, as we all know around here, are a blast to ride.

Correct word choice, man-gled, by man, not the frame's fault. Just guessing, but I doubt as many CL450's were thrown over rocks and logs.

 

[ancientdad]

Just guessing, but I doubt as many CL450's were thrown over rocks and logs.

Uh, yup. I took mine off road once during high school, as long as you were on the throttle and blasting debris behind you it handled okay... the second you let off it wallowed around like a pig in slop. A 425 lb steel and aluminum pig. The scrambler bars could have been a foot wider and it would not have helped at all.

 

[ballbearian]

My current CB350 project started with a damaged frame that I have decided not to use. Although it was a CB, it was made up as a CL and I suspect that one of the POs abused it on trails. The step bar was mangled and had been welded to the frame on the kickstand side. The center stand was absent and the lower frame tubes were bent slightly, as if they landed on rocks frequently. No skid plate. I suspect that many of these CLs were used that way for the reason that AD mentioned. They were relatively inexpensive and, as we all know around here, are a blast to ride.

I just had a thought on your first frame. I could harvest cadaver parts from Mousetown to use on it, since you are becoming a welder. I mean if it's got a title, it would be worth trying to save. I got an extra centerstand and it's parts, probably a footbar too.

 

[ballbearian]

My current CB350 project started with a damaged frame that I have decided not to use. Although it was a CB, it was made up as a CL and I suspect that one of the POs abused it on trails. The step bar was mangled and had been welded to the frame on the kickstand side. The center stand was absent and the lower frame tubes were bent slightly, as if they landed on rocks frequently. No skid plate. I suspect that many of these CLs were used that way for the reason that AD mentioned. They were relatively inexpensive and, as we all know around here, are a blast to ride.

If you got a title for that frame, I could send you the left side mount tube, from Mousetown, to further your welding chops, and a centerstand too.

edit: Oops! I thought I lost previous post

 

[stl360+450]

I just had a thought on your first frame. I could harvest cadaver parts from Mousetown to use on it, since you are becoming a welder. I mean if it's got a title, it would be worth trying to save. I got an extra centerstand and it's parts, probably a footbar too.

That's a very thoughtful offer. It was disappointing going through the game of getting the title for that frame and then not using it, so it would be nice if it did get used. I'm just not sure I'll be up for building it. I have a 1977 CB750F that needs some attention and, before I know it, I'll be chin deep in the coming school year (teaching) and progress will slow down again.

I would be happy to give that frame and title to anyone on VHT if the logistics could be worked out. One oddity is that the DMV mistakenly put CL on the title at some point even though the VIN plate says CB. I'm guessing an inspector was fooled by the front fender and high pipes. FYI: I occasionally visit friends in Pittsburgh, which would put me close enough for a swap meet between there and Hagerstown, so save the Mousetown leftovers!

 

[ballbearian]

That's a very thoughtful offer. It was disappointing going through the game of getting the title for that frame and then not using it, so it would be nice if it did get used. I'm just not sure I'll be up for building it. I have a 1977 CB750F that needs some attention and, before I know it, I'll be chin deep in the coming school year (teaching) and progress will slow down again.

I would be happy to give that frame and title to anyone on VHT if the logistics could be worked out. One oddity is that the DMV mistakenly put CL on the title at some point even though the VIN plate says CB. I'm guessing an inspector was fooled by the front fender and high pipes. FYI: I occasionally visit friends in Pittsburgh, which would put me close enough for a swap meet between there and Hagerstown, so save the Mousetown leftovers!

If you are driving, you may well pass thru Hagerstown on I-70. Since I have two more CB350's without titles, I'd give it a good home and it would be fun to meet. I would expect to make a contribution.

 

[wentwest]

For the first 50 years of my life I watched cars, trucks, bicycles, trash cans, buckets and anything else made of steel just rust away. I spent lots of money getting Babe the welder to put another plate on a cracking frame on one Chevy pickup or another. My 64 Chevy pickup finally went to the scrap yard when the whole cab lurched away from the frame so hard the steering column was pinching. My 67 Tempest Le Mans convertible just sighed and sagged so far down the doors were jammed.

Then we moved to California. Things just don't rust here. Nuts come off bolts that haven't moved in 50 years, no problem. None of my project scooters and bikes has had any issues with rust, and some have sat outside under a tree for a decade.

I'd say those lower frame rails are broken because of rust. If it was a top rail maybe it would be something else, but those lower parts, right next to the wet earth in the East or Mid-West, are rust targets.

 

[Richard Pitman]

When I first got my CL175 and started to rebuild it, I found a rust hole in the bottom left frame rail, where water would collect when bike parked on side stand. One 'expert' I asked told me that the frame was scrap. Not happy with that verdict I took it to a local powder coater, who had a fabrication guy next door. I hoped that he could cut out the rusty tube and replace it. In the event, he just welded up the hole, linished the weld, then frame got powder coated. Must be 10 years ago now, no sign of frame repair failing.