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Owner if he did the damage would have known he did it, that is some serious damage. Engine is done as of now, you have transmission gears showing there. No glue will hold that and don't care what the other guy said. You must have the pieces to begin with but the damage goes across case split line and that requires crush to seal properly. If you have the pieces welding at the least to fix it and by the best, amateur work there will just bring more grief. The main cases are matched pieces and bought in pairs. Pic here......


Some incompetent let the chain get way too loose to jump or break, it did and the pinch point there then wrecked the cases.
 

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The only SOHC 750 engine you are going to get will be a dead one at that price. A good useable CB750 engine in long running shape is worth easily $1000, they are highly valued by the collector market. Just the bare GOOD cases alone can go for $300 easy.
 

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I've got DOHC for that that then ran for years and even free ones but those are not SOHC which has been locked onto by collectors as worth far more while making less power than DOHC. Any SOHC stuff figure out a good price then 3X-5X that as what they commonly go for.

Like Chrysler true 426 Hemi (I worked on them), nothing special there but just buy parts for one.
 

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One needs the pieces that came loose, they include part of the case split line and you will play h-ll getting around that. Go back and look at the pic showing trans gears showing, it won't matter how good the welding guy is. First thing he will ask you is where are the pieces? BTDT that type of massive repair before on $20K cost race heads.
 

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There is no logic or fact there, clearly that situation does not match the OP here at all. The fracture here does not go off into fluid at all and the bolt boss is a localized stiffener that is not present in the OP situation. So much for the 'facts'.This one was fixable but the other is not, not without those filler pieces. Still no mention of them.
 

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You're talking a solid patch some 2 inches wide X maybe 4 inches long, there is no such survivable epoxy patch on earth that can do that. If the pieces aren't there even the best welder on earth will pass on the work, there is too much material missing. Looking at enough heat replacing it to warp nearby surfaces, the last thing you should be doing. The split line crush stress alone wrecks the idea. That area is already a known weakness point on SOHC 750 cases, they broke plenty of them there.

I've both welded and epoxied race heads at $20,000 each to recover them to use again; I got a pretty good idea of what will work and what won't.
 

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New cases = new engine in difficulty level.

Yes, farmers have a 'fix' for everything and I would have gone further but wiped what I was going to say. I note the lack of the word 'good' put in front of 'fix' though.
 

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Go down to 3rd or 4th big pic on the left and does it look familiar? That one not as bad as here onsite. Read the text, the split line killed them, the fix leaked and wrecked rest of engine when it ran out of oil.

That kind of damage CAN be fixed but in no way are you going to without a complete engine teardown. And the plate fitment and welding will have to be top shelf stuff, no farmer work. The split line machining will have to have an expert on how far to cut the plate down for crush. You're talking within .002" for SURE, that is too much error itself.
 
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