Cracked R100 jug - is it useable?

gog

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I have a spare pair of barrels but one of them is missing a chunk out of the sleeve section that sits inside the crank case. it looks bad but I was thinking it may still be useable as the piston should still stay straight in the bore, the rings come nowhere near that far back and the seal between barrel and case should still be good.

These are the only barrels I have left, so if this one isn't useable I'll have to find another matching one.

What do you guys think? Am I going to risk mangling things up by running this?

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dress the edge by the rings , and you may well get away with it BUT .....run it for a couple of 100 miles and pull it down and have a look .
 
My gut says dont chance it - I wouldnt.

Do you know what caused the damage? There may be other unseen damage which may manifest itself at a later stage, possibly with disasterous consequences. It also looks like there is some kind of scoring leading from the damaged area?
 
There's highly likely to be invisible stress lines running through the remaining sleeve.
I'd have it annealed even before I risked using it.
 
I can't see any other damage than the chunk missing. i bought them last year as a pair and only briefly looked at them before putting them aside. when I got around to inspecting them, I noticed it was cracked, and when I removed the piston from the bore it just fell off. I don't know if it had been damaged in transit but I couldn't get hold of the seller and it was paid by BT so not much I could do especially as a good 4 or 5 months had gone by.

it's not *that* much deeper than the existing arc that's cut out from the factory. I have chamfered the edges so I don't think I would struggle to get the rings in. I can't afford to replace it really at the moment, and the later nikasil ones seem to be hard to find in decent nick. I think I will put it in and turn it over by hand, see how it feels. if I have any doubts at all I'll not fire it up. will be a few weeks until I'm at that stage anyway as the engines still out.
 
The scoring looks like honing marks to me. I would say if your piston and rings will fit and be within tolerances then it could be a runner. Depends really on how far down the piston skirt comes. If it comes down to, or below the damaged area then at the very least some dressing of the inner edge of the damaged area would be needed. I know the correct engineering answer would be to replace with a new part, but if you were in India, that would be dressed, beaten, shaped or whatever and made to run again. I think there could be life in it yet.
 
unless that can be done with a mapp torch wielded by a halfwit joe then I think replacement would be preferable. after you spend the time and money having an engineer trying to fix something like this, it's probably going to work out not much different cost wise. i will start looking for another one. bit gutting as I paid good money for these, and my own fault really for not inspecting them closely when they arrived. cest la vie.
 
KMD yep that is the honing marks, highlighted by my grubby oily fingerprints pawing at it after chamfering the sharp edges.

how far the pistons come down the barrels towards that area will be the first thing I check.
 
You should be able to get the heat from a map torch to anneal.
Basically the heat is restructuring the crystalline particles of the metal.
Try YouTube for help.
 
will have a look. I've annealed copper washers before but never considered it with something like this. concerned that it could perhaps make it more brittle or mishaped enough to cause the piston to stick - it currently slides in and out like it should.
 
solidstate you are right. the camera and light makes them look more pronounced, but there are marks there. looks like something had indeed scored towards the area that snapped. it may well have been the piston that knocked the cracked peice out. however I can't feel any scoring with my fingernail at all.
 
I wouldn't even ask.

Just dress the side nearest the piston with a dremmel to take the sharp edge off it and install.
There is nothing wrong with it. Forget all the garbage about annealing. It's just a casting, and you have a tiny bit out of it. So what? It will still work perfectly.
Myke
 
Annealing / heat treating aluminum is completely different to annealing other metals, do a google search.
But, please, no foul mouthed abuse if you find out something you didn't know and thought you did -------------.
I am in the - dress the edge and fit it camp - looks like handling/transit damage to me, but there are a few proprietary crack detection systems around if you are worried about the remainder of the cylinder,
 
thanks all for the input. I will see what happens when it goes together after dressing with the dremel. if it works, great. if not, I'll deal with that then.
 
Nippy Normans supply Touratech, Wunderlich, Desert Fox and many other makes of accessories.
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