Honda CB750 Sandcast
General Category => General Discussion => Topic started by: acruz on April 24, 2018, 03:35:35 pm
-
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
-
Arnold, can you attach pictures of the problems areas?
-
I would try to save it. You will probably need a K0 donor frame, but that shouldn't be too expensive.
-
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.
-
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.
-
The second area of concern is the section where the battery bracket goes. If you look carefully someone welded this whole section.
-
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.
-
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!
-
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.
-
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:
(https://farm4.staticflickr.com/3865/14427646000_300a46708e_b.jpg) (https://flic.kr/p/nYVsvf)
And here is frame 1378:
(https://farm4.staticflickr.com/3900/14427904427_77c89ab8bb_b.jpg) (https://flic.kr/p/nYWMjT)
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.
-
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"
-
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.
-
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.
-
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?
-
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.
-
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. Does that seam like a plausible plan?
The reason i asked, there are a number of different approaches one can take when considering best decisions for restoring a frame in this condition. I am assuming you have made a commitment to this frame, an even though cost for repair is a concern, in your mind you're prepared to learn all the considerations to bring this frame back. I admire and respect your desire to restore this frame; know all things are possible. Be prepared to network as much as is necessary to help you decide the approach you ultimately take. My advice is take your time, in your locale, there must be individuals who do frame repair work and/or find a good welder/repairer (i believe you said welding is not one of your strengths - nor mine). Part of your preparation for deciding what your approach will be is to get familiar with the nuances and distinctions of frame 2568 in contrast to earlier and later vin ranges of sandcast frames as compare to early and late K0 frames -and- later frames. (i would say research of this forum, posting pics, asking questions and also being on the www.sohc4.net (http://www.sohc4.net) forum will be helpful to you.) A project such as this will take time, much more so in the research process and parts acquisition process and determining the repair approach process. Knowing up front this is not a project for anyone short on patience, persistence, perseverance, and willingness to learn what is necessary to make the frame right is 9/10th's the battle. You may want to put this link in your files - http://www.wascoframe.com/ (http://www.wascoframe.com/) These guy are premier frame restorers, at least in the antique motorcycle fellowship. They repair any/all frames. The value, increasing desirability and difficulty finding these sandcast bikes is at the point, parts we would have not considered restoring, saving, repairing are now parts we evaluate from a different perspective. if your frame were mine, i would learn what is necessary to know about the frame, find donor parts/frames, and go from there. in my experience, you very most likely are going to need donor parts. the other thing, is making sure the frame is straight, plumb and true after the repairs have been effected. hope this is helpful.
PS - your approach is certainly one i would consider. to me, it sounds like a good one.
-
A good post and very wise advice Mr Swan.
-
Thanks Steve. I definitely want to try to preserve this frame as much as possible. I did find the company that you had recommend on a google search and they do have a CB750 frame on their home page. I know it will take time and certainly some money to do this right. I have been planning this for several months and i'm trying sell off my collection of motorcycles to do this and another SC project that I acquired. Thanks for the words of wisdom.
Arnold
-
Thanks Steve. I definitely want to try to preserve this frame as much as possible. I did find the company that you had recommend on a google search and they do have a CB750 frame on their home page. I know it will take time and certainly some money to do this right. I have been planning this for several months and i'm trying sell off my collection of motorcycles to do this and another SC project that I acquired. Thanks for the words of wisdom.
Arnold
i don't know about wisdom, but i do know Mr. McGovern loves it when i talk dirty to him.
-
I added a piece of a left front downtube from a 76 frame into a diecast. The pieces appeared identical and the tig welds made the sleeved joints invisible. I also repaired the sidestand tube and replaced the lower top bars but did use the Gordons removal kit since this bike is a resto mod. The longer I own it though the less mod and more resto it is. Someday I might feel inclined to remove the kit.
We do some racecar repair and it's not such a big deal here.
-
Don, Thanks for that info. Would you be able to show some pictures of how you repaired the frame? I just wanted to see how you were able to splice the frame sections together. I have been giving this much thought and I was thinking the best way to fix this problem is to remove the bad section of the frame which consists of the rear two thirds of the rear frame. I would then replace this section from a K0 frame.
For the last week and a half I have been searching online for a donor K0 frame and I actually found two K0 frames. One frame is #25xxx and is just a rolling chassis that comes with extra parts. The other frame I found was actually a complete bike, also #25xxx, minus the exhaust and seat. This bike I might save for a later project as it came with a title.
I attached a picture of the areas I plan to cut out and replace. Let me know if anyone has done this type of repair. Any suggestions would be appreciated.
I was thinking about sending this to a guy up in washington state but I was referred to a frame specialist in Sacramento which is only about 45 minutes from my home. I might go this route and have them do this repair as I can bring both frames myself instead of paying shipping costs to Washington.
-
https://www.kijiji.ca/v-view-details.html?adId=1355798421&utm_campaign=Kijiji_Alert_AB_Testing_A_LISTIMGS&utm_medium=email&siteLocale=fr_CA&utm_source=alerts&utm_campaign=Kijiji_Alert_AB_Testing_A_LISTIMGS&utm_medium=email&utm_source=alerts (https://www.kijiji.ca/v-view-details.html?adId=1355798421&utm_campaign=Kijiji_Alert_AB_Testing_A_LISTIMGS&utm_medium=email&siteLocale=fr_CA&utm_source=alerts&utm_campaign=Kijiji_Alert_AB_Testing_A_LISTIMGS&utm_medium=email&utm_source=alerts)
I found that here in Quebec,with paper but chrome frame...
-
Hi Bowswell, do you know the number of the frame in Quebec?
Thanks
Arnold
-
Hi Bowswell, do you know the number of the frame in Quebec?
Thanks
Arnold
The guy is supposed to send me a pic and VIN today Arnold. I’ll post if he does.
-
Here’s the frame in the ad.
-
Thanks for the pictures Wayne. I think the cost would be a little much though with transport from quebec to california. I was able to locate a frame in Oklahoma for only $125. I'll probably use this one for the repairs. Has anyone done this type of fix?
-
Ouf don’t look good lost some part somewhere...
-
Has anyone done this type of fix?
Hi Acruz,
I did it to repair the crossbar of the center stand.
It is necessary to incorporate smaller diameter tubes inside the tubes of the frame at the places to be welded, this is called reinforcement gussets, it will first be necessary to make some holes of 5 or 6 mm on the tubes of the frame of each side near the cuts in order to be able to make soldering points on these outer holes in order to weld the internal reinforcement gussets. The cuts of the frame tubes should be filed at an angle to ensure a good thickness of metal when you remove the solder thicknesses for a good finish.
And be very careful about the restriction of the metal, when you do the welding, because the welding pulls a lot on the metal and it may deform the frame, avoid arc welding and use instead the MIG (wire weld).
The replacement part must not be shorter, it must be cut longer than 1 or 2 mm to be able to adjust it perfectly, and the ideal is that it comes back by forcing very slightly to avoid the restriction of the welding.
I did my best for the translation... ;)
-
Gerard, excellent translation! i really respect the amount of time and effort you take to make your fine posts.
-
Thanks Gerard for the advice. To be honest, I don't have great experience with welding. Once I get the donor K0 frame, I'm gonna see if my welding buddy can do the rear end swap. I may try practicing welding though on a different frame.