Blown engine - Hole in crankcase :-(

Information relating to the Matchless G9 or AJS Model 20 500cc twin
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Cliff-1959
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Blown engine - Hole in crankcase :-(

Post by Cliff-1959 »

Well, it seemed like a good idea to take part in the VMCC parade lap at the Classic TT this year. The first half of the course went really well, but my poor Model 20 really struggled on the climb up to the mountain. Just after the Gooseneck there was a bang and the engine power dropped dramatically. When I pulled over I spotted a 50p sized hole in the top of the crankcase just in front of the left barrel.

When I got home I had a better look, and you can move the left piston with a screwdriver, so I am guessing that I have snapped a con-rod.
The right piston still looks and moves OK when I kick it over.

To be honest, I don't know what to do next, and would really appreciate your thoughts. I am OK with removing the engine and stripping it, but I don't want to do that and find that I can't get parts. I'm thinking con-rod, piston, valves - maybe even a crankshaft? I haven't seen these parts anywhere for sale. Plus there will obviously be lots of smaller stuff I need, like gaskets etc.

The rest of the bike is pretty much mint, so I don't mind putting the hours in, but I don't want to leave it as a basket case.

So what would you guys do?
Plodding along ...
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Rob Harknett
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Re: Blown engine - Hole in crankcase :-(

Post by Rob Harknett »

You have no option except pull it apart, unless you just keep the bike as a non runner. You may not had seen these parts for sale, simply because you have not been looking for them. The club has many parts and AMC Classic spares many S/H bits, in particular the big lumps like casings perhaps. You may not even have to look any further. Don't give up on the bike, there's many other's undergoing restoration needing far much more work and parts.
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Cliff-1959
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Re: Blown engine - Hole in crankcase :-(

Post by Cliff-1959 »

Rob Harknett wrote:You have no option except pull it apart, unless you just keep the bike as a non runner. You may not had seen these parts for sale, simply because you have not been looking for them. The club has many parts and AMC Classic spares many S/H bits, in particular the big lumps like casings perhaps. You may not even have to look any further. Don't give up on the bike, there's many other's undergoing restoration needing far much more work and parts.
Thanks Rob,
I will get my spanners out then. I don't mind as long as there is a good chance of getting the bits. It will be a good project for the winter eh?
Plodding along ...
G15 Roy
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Re: Blown engine - Hole in crankcase :-(

Post by G15 Roy »

If your bike is a 500 Alternator bike then crankcases will be hard to find. But i think there was a pair being sold at the last kempton jumble.
Roy
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dave16mct
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Re: Blown engine - Hole in crankcase :-(

Post by dave16mct »

It may be possible to weld the crankcases. I would think T&L could do it. I had some done locally and I'm looking into another local engineer who is good at alloy welding.
Dave.
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clive
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Re: Blown engine - Hole in crankcase :-(

Post by clive »

G15 Roy wrote:If your bike is a 500 Alternator bike then crankcases will be hard to find. But i think there was a pair being sold at the last kempton jumble.
People, even ex-presidents, who try to sneak adverts into the forum may find their legitimate adverts for a Wasp deleted from the website. :rofl:
clive
if it ain't broke don't fix
poptsova
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Re: Blown engine - Hole in crankcase :-(

Post by poptsova »

Hello if you need your case welding its poss that i can help have done many over the years post a picture or send me a private message .
G15 Roy
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Re: Blown engine - Hole in crankcase :-(

Post by G15 Roy »

clive wrote:
G15 Roy wrote:If your bike is a 500 Alternator bike then crankcases will be hard to find. But i think there was a pair being sold at the last kempton jumble.
People, even ex-presidents, who try to sneak adverts into the forum may find their legitimate adverts for a Wasp deleted from the website. :rofl:
It was not me that had them it was the Ex Chairman. ;) ;)
Roy
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clive
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Re: Blown engine - Hole in crankcase :-(

Post by clive »

Ah a recommendation rather than an advert
clive
if it ain't broke don't fix
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Cliff-1959
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Re: Blown engine - Hole in crankcase :-(

Post by Cliff-1959 »

poptsova wrote:Hello if you need your case welding its poss that i can help have done many over the years post a picture or send me a private message .
I was thinking of trying to get it welded, it has the engine number on this side, so I didn't want to change it if at all possible.
I actually have a piece of the case from the hole, it had somehow ended up on the cylinder head!
I will try and get a picture up on here so that you can take a look.

Thanks to all for the replies.
Plodding along ...
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