Blown engine (19/8/2018 update)

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FWIW I wouldn’t bother trying to fix that crank case, I’d put the money towards another set. They do come up from time to time. New ones are available too, but not cheap.

As you’ll be needing new rods and pistons, this’d be a great opportunity to go for JS lightweight pistons and rods!

920 or 850? I think most on here would strongly suggest re sleeping to 850.

Personally, I’d use it as an excuse to try the 920 route!
 
Fast Eddie said:
FWIW I wouldn’t bother trying to fix that crank case, I’d put the money towards another set. They do come up from time to time. New ones are available too, but not cheap.

As you’ll be needing new rods and pistons, this’d be a great opportunity to go for JS lightweight pistons and rods!

920 or 850? I think most on here would strongly suggest re sleeping to 850.

Personally, I’d use it as an excuse to try the 920 route!
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Well the cases are with a friend who is making a plate to fill the hole, will see what the welder thinks. Ive put a wanted up for a set and keep trawling ebay etc.
i had thought of the leightweight set-up, will see how money is when it comes round.
A 920 has an certain appeal to it and is something i had considered last time round. the bore is currently at 0.060 over and will need sleeved.
as i said this will be a slow and long project due to the house move etc.
 
I've got a matching hole in my crankcase, with the same journey ahead of me that you do. I haven't torn into my engine yet but I'm sure it will be a similar right mess.

I lucked out for another set of cases for a "very good price". They are out there. I'm also fortunate to have a parts bike to draw from if I need to.
 
went to see my friend on Saturday and he's made the patches.
I'll let the pics do the talking

milled out the holes

V grooved for welding.

the pictures don't really do this justice, the work he has put into this is astounding. just looking to find a welder now.
 
looks like the patch's will be better than the original case.:D new name for that engine; "Patches" i'm depending on you son....
 
I would suggest you get your welder to address the mullered mounting points too.

They are super neat patches for sure!

Your challenge now is to find a welder who won’t distort the hell out of the case...
 
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Pre-heat the cases before you weld. No guarantees for warping the mating halves or bores of the crank. Good luck.
cheers,
Thomas
 
Good patch plan. Bolt those cases together, and bolt on the jug to restrain it while (required) pre-heating & welding. It will work just fine. 38 years since I welded my first Harley cases.
 
In 1975 I broke a connecting rod with results that look very similar to these photos, except everything wasn't burnt black. My hole was high up on the back and I wasn't losing any oil on the side of the road, so quickly realized my root cause was lack of oil. I had neglected to check the level in the tank and had run down to maybe 1/4 of the tank capacity. I mentioned my tragic event to a machinist and he offered to try and patch the hole in the case, and he did. I only provided the drive side with the hole, far too dumb to think of bolting cases together with barrels on to try and control warpage. My hole was about 1 1/2" at the widest, and this guy just welded it up with (I assume) aluminum rod. Long winded, but I wanted to say that I bet your excellent looking patch job will work just fine.
A question, I recently opened up my '72 Combat crank and found virtually nothing in the sludge trap. I've seen a similar 'clean trap' picture here, and I've read about clean findings in a thread or two. Has anybody ever in the history of mankind found significant sludge in a crankshaft trap?
 
Atlas Commando said:
In 1975 I broke a connecting rod with results that look very similar to these photos, except everything wasn't burnt black. My hole was high up on the back and I wasn't losing any oil on the side of the road, so quickly realized my root cause was lack of oil. I had neglected to check the level in the tank and had run down to maybe 1/4 of the tank capacity. I mentioned my tragic event to a machinist and he offered to try and patch the hole in the case, and he did. I only provided the drive side with the hole, far too dumb to think of bolting cases together with barrels on to try and control warpage. My hole was about 1 1/2" at the widest, and this guy just welded it up with (I assume) aluminum rod. Long winded, but I wanted to say that I bet your excellent looking patch job will work just fine.
A question, I recently opened up my '72 Combat crank and found virtually nothing in the sludge trap. I've seen a similar 'clean trap' picture here, and I've read about clean findings in a thread or two. Has anybody ever in the history of mankind found significant sludge in a crankshaft trap?
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Can we assume the welded up case was ok?

Did your 72 have an external oil filter?
 
The welded up case looked good. I started typing that I actually re-used it and ran it, but my memory is poor enough I'm not sure that it really happened. I seem to recall painting the cases with black engine paint to conceal the repair and thought I had that engine back in the bike for a season, but I simply can't recall assembling the crank and cases, so maybe I slipped in another engine. When I get to trying to build up my Atlas frame into a bike, I'll be taking a look at that case set for probable use. I guess I better get it measured for alignment.
As for the '72 and the sludge trap question, there was no external oil filter. I don't know the mileage on it.
 
Fast Eddie said:
I would suggest you get your welder to address the mullered mounting points too.

They are super neat patches for sure!

Your challenge now is to find a welder who won’t distort the hell out of the case...
Click to expand...

its not clear in the pictures but they have been V'd for welding.
CanukNortonNut said:
Pre-heat the cases before you weld. No guarantees for warping the mating halves or bores of the crank. Good luck.
cheers,
Thomas
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The cases are still with my friend but the hope is that he can find a welder through his work, as he has access to the facilities to pre-heat.

850commando said:
looks like the patch's will be better than the original case.:D new name for that engine; "Patches" i'm depending on you son....
Click to expand...

They really are better than the pictures make them look. the work that he has put into this astounding.

i'll need to find out how to transfer the pics from his phone to mine, shows the whole process.

Just seeing it like this has given me hope
 
What you could do is clamp the case to a welding bench to stop the case from warping, clamp it down simlar to clamping down on a milling bed, I just made a welding bench out of 10mm plate steel just for this clamping things down on it to weld or tack welding jigs etc.
Anyway nice patch, now just find a welder who knows his stuff, maybe someone who builds alloy boats, good luck with it.

Ashley
 
ashman said:
What you could do is clamp the case to a welding bench to stop the case from warping, clamp it down simlar to clamping down on a milling bed, I just made a welding bench out of 10mm plate steel just for this clamping things down on it to weld or tack welding jigs etc.
Anyway nice patch, now just find a welder who knows his stuff, maybe someone who builds alloy boats, good luck with it.

Ashley
Click to expand...
Strong backing as you describe is a useful tool in many instances. But, in this case it will only restrain in one plane, whereas, the two halves together give that AND the flanged mating surface of the crankcase halves a better chance at staying round.
 
Adam_R said:
Was out on the 850 for a run last Sunday, slowed down for a bad corner and started to accelerate up the hill, clatter clatter! Pulled in the clutch and ground to a halt.
looked down to see oil and a mangled shell. instantly knew the worst :(
spent the next 2 hours looking all over for parts.


I had initially come to the conclusion of oil starvation , but am not so sure as there was oil on the ground and was still dripping when i moved the bike to the side of the road.

Any Ideas?
The engine was rebuilt less than 1000 miles ago, all new bearings etc

as for what to do next, i've no idea
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While any blow up can be unique, I seem to have seen this similar blow-up scenario on several local club members bikes/ norton heavy twin.
Fresh rebuild, sometimes big bux...new tight crank clearances coupled with a worn oil pump.
Journal gets hot because it's not being adequately cooled by the oil , metal scores-melts-seizes- big end snaps
Did your rebuild have a new pump or a "competent" testing done.
I did similar on my 1970 command at 105mph with resultant rear wheel lock up. luckily I did not dump the bike and lived. (obviously)
45 years later , I know better now.
I test pumps for local club members on my pump rig, and feel I have saved at least a few from a similar fate.
 
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