Author Topic: Crack on C/Hd  (Read 737 times)

Offline sprint

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Crack on C/Hd
« on: 25.08. 2013 09:24 »
Have noticed a crack on the C/Hd, see photos, R/H Exh side.

Is this a common problem as I have a friend who has a SR that has cracks in the same position on both sides? These take the load from the head steady so is that what causes the crack?

Can they be repaired as any welding is going to be tight with the finning?

Online muskrat

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Re: Crack on C/Hd
« Reply #1 on: 25.08. 2013 11:47 »
G'day Sprint.
It does look like a crack. There has been a fin repair close by, wonder if that had anything to do with it.
A good (read very good) welder would be able to tig stitch it.
Both my alloy heads are OK, but the '51 (alloy head) is steadied from the front (as a plunger model is) and my cafe is steadied from the rear bolts only. They were steadied normally for the first 40 years of their life.
Cheers
'51 A7 plunger, '57 A7SS now A10CR,  '83 CB1100F, 88 FXST .
Australia
Muskys Plunger A7

Offline chaterlea25

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Re: Crack on C/Hd
« Reply #2 on: 25.08. 2013 23:07 »
HI Sprint,
A lot of heads cracked during the manufacturing process as the alloy is thin in this region around the bronze inserts
They also crack from ham fisted owners over tightening and not cleaning out the crap from the bottom of the blind holes *sad2*
I would think to weld up properly you need to remove the bronze insert and start from there, then screw in a timesert insert or similar

On the other hand in 30 years time the "crack will be ninety"  *lol* *lol* *lol* *lol*

Cheers
John
1961 Super Rocket
1963 RGS (ongoing)

Online trevinoz

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Re: Crack on C/Hd
« Reply #3 on: 25.08. 2013 23:20 »
I would be inclined to leave well enough alone as long as the rocker box is secure, as it appears to be.

Trev.

Offline sprint

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Re: Crack on C/Hd
« Reply #4 on: 26.08. 2013 10:24 »
Thanks for the replies.

Not had the bike long so I don't know how long the crack has been there.

I think, as suggested, it may be wise to just leave it at the moment and keep an eye on it and see how/if it progresses and then deal with it.

John, you made a reference to bronze inserts?

I was helping a friend with his SR over the week-end (who has a crack on each side) and we noticed that there were bronze inserts and assumed that they had been done at a later time as a repair? Were they fitted as standard during the manufacturing process?

Andy

Online trevinoz

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Re: Crack on C/Hd
« Reply #5 on: 27.08. 2013 07:15 »
I'll answer for John, yes the inserts are standard.

Trev.

Offline sprint

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Re: Crack on C/Hd
« Reply #6 on: 27.08. 2013 09:02 »
I'll answer for John, yes the inserts are standard.

Trev.

Thanks Trev