Topic: The latest addition: 1975 CB750 for $300

[grcamna2]

Jack,  I worked at Montgomeryville Cycle and Riff's back in the day.  It was perfectly legal to replace a frame and stamp in the original numbers. To me, it follows that you could buy any frame, restamp it with your numbers-you'd still have your survivor but with a replaced frame. .. Larry

Larry,
Grcamna2 here, do you mind if I ask....
   What will happen w/ the old numbers? & can a person do this as a private owner?
I asked a man if I could do this once & he said it was ok...I was just wondering what would happen if I ever had a DMV/PENNDOT inspector do a spot check...wouldn't I need to get it sort of "Approved" by some type of inspector here in PA. ? I hate to get "hung up by my toes" or have my bike confiscated by the "authorities" here.
I wonder if there is a notary around who would be able to straighten this out ??

[Terry in Australia]

I wouldn't be at all fussed about the rust, the fact is that most CB750 frames will have some internal rust after 30+ years, it's just that if you don't see a hole, you assume that it's not rusty. The frames were never designed to be sealed from water ingress at the frame joints, and Honda had no idea that dickheads like us would still be riding them around after so many years, I'm sure.

A common spot for rust on 750 frames is the shifter side rear engine mount plate/swingarm bolt bracket. There are small gaps between the bracket and the frame tube, and over time chain lube and mud build up in there and quite often rust will form. No biggie, clean all the goop out and weld it up, problem solved. Good thing is that it's only mild steel, and easy to repair. There are probably plenty of guys here with rusty frames that don't even know. Cheers, Terry.

[Rigid]

Jack,  I worked at Montgomeryville Cycle and Riff's back in the day.  It was perfectly legal to replace a frame and stamp in the original numbers. To me, it follows that you could buy any frame, restamp it with your numbers-you'd still have your survivor but with a replaced frame. .. Larry

+1 in Indiana but the donor frame has to be destroyed.  No one needs two bikes floating around with the same vin. I am leaning towards competent repairs on this one though.  Tap test the entire thing with a punch (lightly) looking for soft spots.  Repairs can be invisible after proper smoothing.  Seeing a stamped neck raises eye brows for people wanting a one owner, original bike.  Bobber/chopper guys could not care less, but you have a nice survivor needing repairs.  IMHO

[wedoo2]

Honda had no idea that dickheads like us would still be riding them around after so many years, I'm sure.

 Cheers, Terry.

That is so funny.

[78whiteorbs]

SCORE!!!!  sweet deal !

[MCRider]

There was a real good post about water in the frame, i doubt if anyone could ever find it. Essentially, the frame has several places where it can breath. If those places get plugged accidentally or on purpose, then condensation will form inside the frame and can't get out. Or just outright water from the elements or from washing it. Rust.

Seems a proper repair should be effectual. ala Terry. Could end up stronger than stock, i think. After all performance guys weld them up all the time.

I doubt the WindJammer had any more to do with it than random. Others complaining of the rust didn't have Windjammers. There should be some weep holes on the bottom sides of the bottom rails IIRC.

[bjatwood]

Does anyone know where Honda might have put the holes in the frame for letting the water/condensation out?
If we knew we could all check our "drain holes" for potential plugs and keep them working like Honda intended...

[MCRider]

Does anyone know where Honda might have put the holes in the frame for letting the water/condensation out?
If we knew we could all check our "drain holes" for potential plugs and keep them working like Honda intended...

Uh yeah, me too.     Assuming I had them, they are powdercoated over now. On some quickie searches, i saw some comments from HM as to drain holes.

[mrjack55]

The K5 has landed!    She's home and safely stored in the garage.  It was a bit of an ordeal getting her off the back of my Ridgeline alone, but I got it without killing myself or dropping the bike.  Here are a few new pics.









I really like this one.  I have no idea what I'm going to do now.  My K7 is in a thousand pieces, and taking up all the space in my garage.  Now I have this gem.  God help me.
*Continued*

[Rigid]

Its a disease, if you starve it, it gets worse.  Enjoy.

[Hondawggie]

mein gott that darn thing is clean clean clean looks like the prior owner was a fuss budget about keeping that machine looking presentable $300 mein gott


did you get your 341s the way I see it $300 for the bike if you pay $400 for the hm341s assuming he took care of them like your new bike the 341s must look good so you pay $100 per pipe and you sell the 4-into-1 now you have a $500 story few might believe we all should be so lucky you called in some good karma on this one its very nice and his custom colors though not stock are cool man congratulations

I have dropped a bike or two unloading by myself good job getting her down

[mrjack55]

The holes in the frame are pretty bad.  I had a chance to really take a good look and some pics.  If I do weld it, it's an engine out and frame striped down job.  I was hoping it would be easier, but alas no.








As you can see, it's quite a hole with others forming and a lot of rust.  If I do repair it, I think I'd need to remove that whole section of the frame and weld in a new one.  I'm not rushing into anything.
*Continued*

[mrjack55]

As for the aforementioned 341 pipes.  Well, I was thinking about those pipes all night.  Should I, shouldn't I?  I really had a hard time justifying leaving them there.  So...I offered him $400 for them.
He took it!






This really it the worst part of the pipes.  One of the headers has some heat discoloration.


All and all, $700 total for the K5, and the 341 pipes, and a few extra parts.  I also got a small fairing, wheel bearings, an extra mirror, extra keys, and a spare set of coils.  Not to shabby. 

[Terry in Australia]

Well done mate, you've really got yourself a bargain. You'll probably need another donor frame to cut a section out of to replace that rusty section, but it's not a huge problem, and it sounds like it's cheaper to buy an untitled donor frame than find a good titled frame to swap all your parts across to. Cheers, Terry.

[Greggo]

Well done mate, you've really got yourself a bargain. You'll probably need another donor frame to cut a section out of to replace that rusty section, but it's not a huge problem, and it sounds like it's cheaper to buy an untitled donor frame than find a good titled frame to swap all your parts across to. Cheers, Terry.

Does the whole bike need to be disassembled for the fixes? 

[Terry in Australia]

The engine will need to come out, and depending on how high up the rust is in the rear frame tubes, possibly the swingarm, but angle grinders with the new super thin cut off wheels are wonderful devices and make frame cuts simple and clean. Cheers, Terry.

[Roach Carver]

I got to admit, those rust holes scare me, but then again so does my wife from time to time.

[Rigid]

All the rust repair, sandblast and first coat of primer, 8-10 hours of hard work.  Easily done in a weekend.  EVERYTHING off the frame, a jig might be handy but not critical if you do one repair at a time.  You could weld your neck assy. to a donor frame but what is the fun in that?

[grcamna2]

Well done mate, you've really got yourself a bargain. You'll probably need another donor frame to cut a section out of to replace that rusty section, but it's not a huge problem, and it sounds like it's cheaper to buy an untitled donor frame than find a good titled frame to swap all your parts across to. Cheers, Terry.

+1 on that...possibly even a crashed frame will work because the engine,as a stressed member would most likely keep that piece of frame from bending; Nice HM341's !

[MoMo]

Wise decision on the pipes.   Many of the 400 fours rusted in the same spot-they usually fall over and damage the bike when it rusts all the way through. Spotting in another frame section would be the best bet, a good welder should be able to do that so one would never know it was repaired...Larry

[Stev-o]

That rust is pretty bad, does not look like "normal" rust as stated in Terry's first post above.

I would start shopping for a titled frame.  Let's all keep are eyes open for him.

Good decision on buying the 341's!

[Rigid]

That rust is pretty bad, does not look like "normal" rust as stated in Terry's first post above.

I would start shopping for a titled frame.  Let's all keep are eyes open for him.

Good decision on buying the 341's!

A low mileage titled frame 

[mrjack55]

The engine will need to come out, and depending on how high up the rust is in the rear frame tubes, possibly the swingarm, but angle grinders with the new super thin cut off wheels are wonderful devices and make frame cuts simple and clean. Cheers, Terry.

I may have found a donor frame locally, so this is my plan Terry.  I will for sure need to get the motor out and most likely the swing arm.  New bronze bushings came with the deal, so it was coming out anyway.  I'll do all of Hondaman's tricks while I'm in there.  Thanks for all the words of encouragement.

Wise decision on the pipes.   Many of the 400 fours rusted in the same spot-they usually fall over and damage the bike when it rusts all the way through. Spotting in another frame section would be the best bet, a good welder should be able to do that so one would never know it was repaired...Larry

Thanks Larry.  It did keep me up last knight.  By the way, this bike came from Montgomeryville Cycle in 75, back when they actually were in Montgomeryville.  The keys came on the original ring from MCC. 

I got to admit, those rust holes scare me, but then again so does my wife from time to time.

Yes, and mine is going to scare/beat the shizzle out of me if she ever finds out that the pipes weren't part of the $300 deal.  Keep this under your hats boys.

All the rust repair, sandblast and first coat of primer, 8-10 hours of hard work.  Easily done in a weekend.  EVERYTHING off the frame, a jig might be handy but not critical if you do one repair at a time.  You could weld your neck assy. to a donor frame but what is the fun in that?

Rigid, I don't work that fast LOL.   I'm going to take my time and get a good game plan together.  No rush on this one.

That rust is pretty bad, does not look like "normal" rust as stated in Terry's first post above.

I would start shopping for a titled frame.  Let's all keep are eyes open for him.

Good decision on buying the 341's!

Yep, I'm already on it.  I have one lined up already.  There is a member who lives pretty local, and he has a titleless 75 frame.  Should be a good donor.

I have the 65mm big bore kit sitting on the shelf.  I was ready to put it into my K7 project, but this may be a game changer.  Since the K5 has 75k on it, I know the engine is going to need work anyway.  I'm not going to molest the K5 that's for sure, so rest easy boys.  I just can't do it.

[Hondawggie]

If not for the other signs of excellent maintained cosmetic appeal I might wonder if the bike saw a pond or lake up close or a flooded garage.  I would not drive the bike with that frame.

One way to assess the soundness is to hand the frame to an aircraft structural shop that has as part of its business, airframe soundness.  I don't know if they x-ray them or how they do that but they have equiptment to find out when metal has been compromised beyond safe levels.  For a $300 purchase it is probably not economical for that type of testing.

Even if you skip the professional metal integrity testing and cutout and 'sister' on new frame tube sections I would not ride it at speed.  That is some serious oxidation there. 

In California there's a law requiring the recording of any vehicle that saw water.  Don't know if you have that type of law in your parts.  To me that frame looks like it was submerged.  Looks scary for doing 75mph next to a tractor/trailer semi and the freeway has potholes here and there.

EDIT Just want to add, sorry, do not mean to be a downer! I still think you have made a great deal, you can often get frames for around $100 or so, but I would *only* buy one locally so you can inspect it in person.  When I looked at the pictures I thought there is almost no chance that wall thickness is 'fine' just beyond the visible holes in the tubing, on the contrary the tubing wall thickness is iffy all around the broken through areas and not worth the risk to repair, the problem might come down to 'how much of the old tubing do I need to cut out to have a safe repair for this bike's top speed' someone down the road might buy it from you and you yourself need to feel safe, again sorry if I came off being a downer didn't mean to.

[Rigid]

Aircraft tubing is tested as I described above, or a grid is layed out on the tube and a spring tester used to look for soft spots.  back in the day, we used a punch and hammer lightly tapping the tube.  Ultrasonic testing may also be used to determine wall thickness and if the inside is rough (rust).  Lastly, and more involved, is eddy current or x-ray.  Those are usually reserved for parts that are worth more than 10 CB750's    A&P, IA, 3*******9 BTW, that repaired frame, or any other for that matter, can be sealed inside with hot linseed oil injected through tiny holes with a syringe.  The crazy purists have sealed the frames and used dry nitrogen with a pressure gage to monitor integrity.