Cracked RH4

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Diablouph said:
Is there a reasonable cost benefit to machining a repair vs new Fullauto head, fully populated and ready to install?
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Only if you have the machining ability to do it for yourself and your time is free. Jim
 
comnoz said:
Diablouph said:
Is there a reasonable cost benefit to machining a repair vs new Fullauto head, fully populated and ready to install?
Click to expand...

Only if you have the machining ability to do it for yourself and your time is free. Jim
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+1 on that statement.
CNN
 
My time is so "free" that I actually have pay people to let me work on my own bike. It's the machining ability, with an emphasis on ability where I am lacking.

If it's basically a push, seems to me the Fullauto is the way to go.
 
How does one know which head is fitted?, looking over the head, fitted in bike, I cannot see any markings, would they be on the underside of the fins, as you look at the combustion chambers, head upside down?,

John
 
mkv750 said:
How does one know which head is fitted?, looking over the head, fitted in bike, I cannot see any markings, would they be on the underside of the fins, as you look at the combustion chambers, head upside down?,

John
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Late 750 heads [RH6] and 850 heads [RH4 or RH10] are marked above the right hand exhaust valve cover.
Earlier 750 heads are not marked. Jim

Cracked RH4
 
Thank you Jim, is that the marks I can just make out, the left side of the photo, above the exhaust valve cover, just to the left, looking at photo, of the top cover retaining stud hole?.

I take it then, the earlier unmarked heads will be RH4 type?,

Thanks,

John
 
mkv750 said:
Thank you Jim, is that the marks I can just make out, the left side of the photo, above the exhaust valve cover, just to the left, looking at photo, of the top cover retaining stud hole?.

I take it then, the earlier unmarked heads will be RH4 type?,

Thanks,

John
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Yes, the RH10 is just visible.

The earlier heads would be RH1 and were not marked. No problem with those.

The RH4 was marked and didn't start appearing till 74 850's or newer. Jim
 
comnoz said:
Late 750 heads [RH6] and 850 heads [RH4 or RH10] are marked above the right hand exhaust valve cover.
Earlier 750 heads are not marked. Jim
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Unless the 750 head has a "C". :mrgreen:
 
Thank you Jim, I was getting a bit worried there!, but no markings on mine, mk v 750.

Swooshdave, certainly glad there is no 'C' on mine!.....

John
 
Thanks LAB, very interesting thread, I shall have the head off my engine soon.

John
 
Reading back through this year-old thread. I don't think mine is cracked. I don't really see any oil smoke upon cold start or with the engine running. The only evidence (besides plug fouling) is oily residue in the exhaust.

Question; Can the intake valve seals be replaced without pulling the head? I have heard of doing this on automotive engines by using compressed air to keep the intake valve in place while the collets, keeper and spring are removed.
 
Danno said:
Reading back through this year-old thread. I don't think mine is cracked. I don't really see any oil smoke upon cold start or with the engine running. The only evidence (besides plug fouling) is oily residue in the exhaust.

Question; Can the intake valve seals be replaced without pulling the head? I have heard of doing this on automotive engines by using compressed air to keep the intake valve in place while the collets, keeper and spring are removed.
Click to expand...

I know of people who have done it, but I'm not so sure it was any easier than pulling the head. Jim
 
I told Jim about a year ago that I was going to change out my valve springs with the head on the bike. He made the same recommendation then and I am now really glad I pulled the head!
Dan.
 
comnoz said:
Danno said:
Reading back through this year-old thread. I don't think mine is cracked. I don't really see any oil smoke upon cold start or with the engine running. The only evidence (besides plug fouling) is oily residue in the exhaust.

Question; Can the intake valve seals be replaced without pulling the head? I have heard of doing this on automotive engines by using compressed air to keep the intake valve in place while the collets, keeper and spring are removed.
Click to expand...

I know of people who have done it, but I'm not so sure it was any easier than pulling the head. Jim
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Seems it would be a lot easier getting them apart than putting them back together. I have seen the deepwell socket-and-hammer method of taking valve springs off a cylinder head, but it would take a helluva tool to compress them and reassemble with the head in situ.
 
I would use the rope method of holding the valves in place rather than compressed air if I was going to try this. I did fabricate a tool to compress the spring and still leave room for getting the keepers in place but like I said, I am glad I pulled the head.

Oh, and I can show you the method of getting the spring and keepers all back in place with the socket and hammer but you have to have room to swing the hammer a bit.
 
motorson said:
I would use the rope method of holding the valves in place rather than compressed air if I was going to try this. I did fabricate a tool to compress the spring and still leave room for getting the keepers in place but like I said, I am glad I pulled the head.

Oh, and I can show you the method of getting the spring and keepers all back in place with the socket and hammer but you have to have room to swing the hammer a bit.
Click to expand...

I'd love to see pics and/or vids of any and all of this, especially the spring compressor.
 
comnoz said:
I have a head on the shelf that I have welded up but never did the machining. I figured I would let it set for a few months and see if it got harder with age. It should be hard by now as that was about 10 years ago....
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Jim,

Going back to an older post.
Would Cryo treating a head with weld repaired ports improve the strength of the welded areas sufficiently?
Not saying it would be economical, but wondering if it would work in these cases.
 
BritTwit said:
comnoz said:
I have a head on the shelf that I have welded up but never did the machining. I figured I would let it set for a few months and see if it got harder with age. It should be hard by now as that was about 10 years ago....
Click to expand...

Jim,

Going back to an older post.
Would Cryo treating a head with weld repaired ports improve the strength of the welded areas sufficiently?
Not saying it would be economical, but wondering if it would work in these cases.
Click to expand...

Good question. It would probably help. Jim
 
comnoz said:
Danno said:
Question; Can the intake valve seals be replaced without pulling the head? I have heard of doing this on automotive engines by using compressed air to keep the intake valve in place while the collets, keeper and spring are removed.
Click to expand...
I know of people who have done it, but I'm not so sure it was any easier than pulling the head. Jim
Click to expand...
I was hesitant to pull the R-10 (thank you, Norton gods) from my '74 due to the aprehension of re-fitting the pushrods, but, after reading through what-t24164-30.html#p318092, the job went amazingly easy. I'm happy to report that, using MFB's trick bungee and Pete's pushrod holders (pusrod tampons, according to Pete), it was done on the first try.

Nathan
 
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