750 TSCC Rebuild or Replace?

[Rich82GS750TZ]

Yeah, that valve adjuster nut must have gone down the cam chain tunnel. I haven’t found it yet. You’re right, put Norm’s engine in so I have a bike to ride. Then totally tear down the original engine his winter.

[zuluwiz]

You should put crime scene tape around that engine. Ok, the valve rockers appear to have stayed in the cam cover, but that adjustment screw went someplace after it ate the chain guide. You will need to find it and examine all the damage it did during it's tour of the engine. Hopefully not too bad. As I said earlier, a total teardown is probably a Good Idea, but it can wait until youve got the new engine installed and running. I think we know what youre going to be doing next winter.

[Rich82GS750TZ]

I didn’t limp it home. I wrote about 1/2 mile. Probably wasn’t quite that far. Didn’t measure it.

[93Bandit]

So, if all 4 intake rockers broke, how on earth were you able to limp it home??? I would think if the rockers are broke, the intake valves wouldn't open and it wouldn't run?

[Rich82GS750TZ]

Checking parts fiches on partsoutlaw, the crankcase has the same part #. That tells that the frame mount holes are in the same place. That at least ensures me that I shouldn’t have any issues bolting it to the frame, and that I can use my case covers. Norm sent me some pics that show cross head screws on the case covers, I have bolts.

Cylinders are the same, as are base and head gaskets.

There are differences in the valve cover, and gasket, and head and head internals, cam shafts and whatnot. I don’t plan on swapping any internals from my 82 to the 80.

And Norm, you certainly don’t halve to clean on my account. I’m just happy to be getting a replacement engine so quickly and within driving distance.

[Nessism]

Also, this engine is out of a 1980 750E 4 valve. It should be the same engine as Rich's 82 750T shouldn't it?

As far as I know it's the same.

Those engines have oiling issues. One of the few GS engine's that are not bulletproof. There is a fix that involves shimming the oil pressure relief valve. Details available in the archives. That said, don't think that's the cause of this engine failure.

[storm 64]

Oh boy, I have to clean the garage/shop, I have company coming over tomorrow! 😲 The engine doesn't look to bad. I sprayed it with grease before I put it into storage. Downside of that, it's a greasy mess. I should have it ready to just remove a couple of bolts and heav it out of the frame tomorrow.
Also, this engine is out of a 1980 750E 4 valve. It should be the same engine as Rich's 82 750T shouldn't it?

[93Bandit]

Contacted Norm (Storm 64). I’m driving to OH tomorrow to get his engine. It needs a new head gasket so I’ll have to tear that one partially down anyway. But at least I know it runs and nothing broken. I’ll keep this thread going with pics and questions as I move forward.

Thank you all for your attention and sympathy.

The GSR is the best forum out there, and this is why. I've been on many many forums, and never have I been on one with more generous and helpful people, than on here.

[GSXR7ED]

Norm is a good guy!

Ed

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[Redman]

Contacted Norm (Storm 64). I’m driving to OH tomorrow to get his engine.. . . . . .
. . . ..

Aint Norm Great ! ?
Aint this forum great, because of guys like Norm ! ?

[Redman]

As far as broken shards going thru engine, that would only be that broken portion of the rocker, right? and those contained in the cam cover, and can see any place where anything could have happened. And is the the cam chain guide the only casualty of that??

That is what case hardened steel looks like when fractured. The inner part looks more grainy that the outer .060” hardened surface.

Ah... I understand what you are saying. THat it did fail all at once on one occassion, and the outter part that is more hardened looks different than the internal portions.
That does make more sense, relative to all four of them failing all at about once from an over rev.

[Rich82GS750TZ]

Contacted Norm (Storm 64). I’m driving to OH tomorrow to get his engine. It needs a new head gasket so I’ll have to tear that one partially down anyway. But at least I know it runs and nothing broken. I’ll keep this thread going with pics and questions as I move forward.

Thank you all for your attention and sympathy.

[TeamDar]

Thanks Rich,

Have you ever noticed that SOME people require to have things explained to them more than others. haa haaa

After a while I did notice that fracture in your PicOfWeek photo, that follower-RockerArm broken.

I am not a mechanical engineer, not a metallurgist, but I worked with one for several years who was investigating mechanical failures. Notice how a portion of that fracture surface along the one edge is smooth. I would suggest that portion was cracked first, and things were still in operation, and the remainder of the piece was flexing and then those mating surfaces in the area of the crack were wearing smooth against each other, and then later the remaining area let loose all at once.
THat probably doesnt help you much, but just something I noticed.

That is what case hardened steel looks like when fractured. The inner part looks more grainy that the outer .060” hardened surface.

[Redman]

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.
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Yes, all 4 intake rocker arms broken. This shows that the cast metal piece broke. I propped it up on the head wall.

........

Thanks Rich,

Have you ever noticed that SOME people require to have things explained to them more than others. haa haaa

After a while I did notice that fracture in your PicOfWeek photo, that follower-RockerArm broken.

I am not a mechanical engineer, not a metallurgist, but I worked with one for several years who was investigating mechanical failures. Notice how a portion of that fracture surface along the one edge is smooth. I would suggest that portion was cracked first, and things were still in operation, and the remainder of the piece was flexing and then those mating surfaces in the area of the crack were wearing smooth against each other, and then later the remaining area let loose all at once.
THat probably doesnt help you much, but just something I noticed.

....
..................Went to shift into second, didn’t get it all the way past neutral, I think and the RPMs shot up way past redline, heard an awful rattle from the engine, .. ...

,

Might that be the awfull "cam slapping" , "valve float" ?
Where rpm is so high that the valves are not following the cams, cam pushes valve down so fast that the valve doesnt return and the next time the cam comes around the valve is still down some, so in case of this cam rocker system, the rocker is floating around, and gets slapped hard on next time around . . . . .
I dont know, I am asking just for this conversation

I have experienced that only a couple times, on shim-bucket engine. Maybe is worse on this follower-rocker system used in these 4 valve per cyclinder engines.

.
Monday when I checked clearances, . .
.

.....

[zuluwiz]

Wow! I've never heard of those parts failing before. And all at once on the intake side only! Very strange. Not a mechanic, but this engine is a strong candidate for a total tear down. I'd keep disassembling until I was sure I'd found all the parts, and all the damage. I'd be looking for a replacement engine. After installing that, that would be the time to rebuild this one. (Just my opinion, FWIW.)

And just as an addendum, that looks like fatigued steel, not cast iron. No way would I trust cast iron for an job like that.