DISASTER - HELP

[tedmagnum]

I bought an africa twin 2 weeks ago for a trip of South America. It had 50,000 miles on it so thought it would be a good idea to change the rings and deglase/hone the cylinder. Well, when i pulled the cylinder up..this is what i found (see pic). The bottom of the cylinder lining has two pieces missing out of it.... I can only asume these pieces are lying at the bottom of the crankcase.. There was a knocking at idle from crankcase when i bought the bike but i heard this was a normal @ trait.

Can anyone think what has caused this and what I can do about it??
HEEEELLLLLP

[YEN_POWELL]

I don't think it's broken, that's how its meant to look according to my manual.

[DaveS]

Yes, I think you can just see the bit here......

[tedmagnum]

God...i need a copy of that manual. Anyone fancy FTP'ing it ??

I was thinking it might be ground that way for the crank clearance but if it if its a scrappy job. In my haynes, the pictures of any liners looks uncut, but that may just be the front cylinder

I thought i was going to have to put a new liner in the cycliner and go hunting in the crankcase....Oh what joy

[Tikka]

You have a PM

[tedmagnum]

Cheers for that mate. I still cant properly make out if the cut outs are normal.

has anyone actually removed their rear cyclinder and found it to be the same as mine (pic at top)

[jvaughan]

The picture looks like they have been machined. the edges are too good to be damage. no residual cracking... they look similar to the ones off my car (V, with the lower edges machined away to stop the opposite piston making contact

[tedmagnum]

Disaster over. According to the official manual, this is a normal cut out. On closer inspection its probably for the crankshaft. I was worried as I havnt seen two "bites" on a liner before. Its fairly common to see one cutout for clearance but 2 is strange.. especially as they look quite random.

[samih]

So how did the old rings look like? Did you measure the gap?

Just interested as mine has now 45k and doesn't use any oil etc.

[robelst]

Disaster over. According to the official manual, this is a normal cut out. On closer inspection its probably for the crankshaft. I was worried as I havnt seen two "bites" on a liner before. Its fairly common to see one cutout for clearance but 2 is strange.. especially as they look quite random.

Maybe these pistons are mass-produced to suit several engine-models?

Anyway, isn't it just fantastic when a disaster turns out to be a case of "they are all like that sir"?