Honda CB750 Sandcast

Need some advice on a frame 2568

acruz · 30 · 6596

acruz

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I needed some expert advice on a frame that I acquired last year.  The frame is number 2568.  It looks to have some repairs on it including a poorly welded kickstand mount and it looks like they welded the middle section of the frame that holds the battery from another CB750 (non-k0).  My question is, should I try to repair these sections? Or is there another option?  I'm not a good welder.  I've done small jobs but not frames so any recommendations would be helpful.
Thanks in advance

Arnold
« Last Edit: April 24, 2018, 04:02:00 pm by acruz »



Sam

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I would try to save it. You will probably need a K0 donor frame, but that shouldn't be too expensive.
Ujeni Motors
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Sandcast #538 Watch the restoration!
Sandcast #6592 All original daily driver.
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vnz00

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Arnold just check those rear shock gussets too - they are normally shorter on the sandcasts/early K0’s.  Rear passenger peg brackets are welded slightly differently too at the bolt hole area too. 


acruz

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Thanks Guys.  Here's the first and most notable problem - the kickstand mount.  If you look at the picture, the frame tubing itself looks like it's caved in.


acruz

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The second area of concern is the section where the battery bracket goes.  If you look carefully someone welded this whole section.


acruz

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The last areas of concern are in the upper front ares of the rear down tubes.  They appear to be damaged or slightly flattened and then rewelded.


Sam

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I still think it can be saved, but it will be more work than I thought before.

I think you will need a frame to take measurements from to make sure you are accurate when placing the side stand bracket and the battery cross-brace. As for the down-tubes, I think a good welder would be able to build up that area.

It will be work, but it is a sandcast frame. Find a good welder!
Ujeni Motors
Sandcast #410
Sandcast #538 Watch the restoration!
Sandcast #6592 All original daily driver.
Diecast #16608


acruz

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Thanks Sam. I had another question, but i don't know if its been don't before.  Can you take the neck or steering column from a SC and put it onto another K0 frame?  I do have another K0 frame and engine.  Just wondering if anyone has done this before.


Sam

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I wouldn't do it personally.

Plus, there are subtle differences between sandcast and k0 frames. I've had them side-by-side to compare before. For example...

Here is the eyelet that bolts to the exhaust on a K0 frame (ignore that it has been cut). Note the location of the eyelet in relation to the two tubes that lead to it. This was frame 35xxx:





And here is frame 1378:



The lower tube that leads to the eyelet is connected higher on the sandcast.

Interestingly, this appears to have changed after 16,608. That frame does not differ from my sandcast frames concerning the eyelet.
Ujeni Motors
Sandcast #410
Sandcast #538 Watch the restoration!
Sandcast #6592 All original daily driver.
Diecast #16608


Steve Swan

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the frame is a bit of a mess, but anything can be saved, it's always just a matter of time, effort, and money.  i would follow Sam's lead if at all possible, find a ko frame to use as a donor.  i may be wrong, but if you cannot clean up the side stand area, then a later donor frame for that area should work fine.  it's one thing if you are saving the frame for a project, vs. repairing to sell.  another thing to know, the tubing on these frames is very thin wall.  probably around 1 mm or .039"   


acruz

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Thanks Guys.  I'm gonna try to save this frame.  Would you guys recommend removing that section that was welded onto the SC frame and weld on the same section from a K0? 

Sam, I went to take pictures of #25xxx and the eyelets for the exhaust actually looks like the one on your SC frame. 


Sam

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Cool! So now we know it happened after 25xxx.

I would have a pro welder take a look at your frame to answer your question.
Ujeni Motors
Sandcast #410
Sandcast #538 Watch the restoration!
Sandcast #6592 All original daily driver.
Diecast #16608


Steve Swan

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Quote
Thanks Guys.  I'm gonna try to save this frame.  Would you guys recommend removing that section that was welded onto the SC frame and weld on the same section from a K0? 

Arnold, what part of the country do you live in?


acruz

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Steve, I live in the East Bay of San Francisco.

With regards to the frame, I was thinking that i could save the front 1/3 of the sandcast frame and have it  welded on to the back 2/3 of the K0 frame.  If I did this, I would have to cut the lower 2 tubes of the frame under the engine, then cut the main tube and the two side tubes above the engine.  Then do the same to the K0 frame.  I would reinforce the welds by putting in a internal tube to bridge the welds.  Then sand it down till the seams flush.  I have a friend who has a welding shop in Oakland and he thinks that he do this fix. 
« Last Edit: April 25, 2018, 04:02:13 pm by acruz »