Topic: unusual bore wear

[AshimotoK0]

One bore of my 3/71 CB500K0 (21k miles) is worn, the other three are OK. There is a slight ridge at the top of the bore (definitely not hard carbon deposit) but its not only at the front (thrust) side but 90° to that too. It's been suggested that I examine the con-rod, wrist (gudgeon) pin  and piston to see if there is evidence of a slightly bent con-rod but I can't detect anything untoward on any of these components. One possibility is that the bore with damage had a broken ring and may have run with it in that state for some time if it did. Any ideas please?

Cheers Ash

[BomberMann650]

Eh, who knows?

Whats ya gonna do to fix it?

[strynboen]

have you got a hydro Lock..or overfloted cylender at any time.?
..a Loose jet can drovn one cylender ,and vash all lube aut..so it vear faster then the rest
...lean running can do somthing like..and give a blocked piston..vho overloadet the rod(sleigtly bend)..but not broke it/...

[jonda500]

I thought the rear of the bores would normally be the thrust side...?
John

[754]

If the rod is bent the wear pattern in the cylinder may have a twist in it.

[AshimotoK0]

have you got a hydro Lock..or overfloted cylender at any time.?
..a Loose jet can drovn one cylender ,and vash all lube aut..so it vear faster then the rest
...lean running can do somthing like..and give a blocked piston..vho overloadet the rod(sleigtly bend)..but not broke it/...

Interesting reply. Thank you...... I can't quite fully understand but I think it is this:-

Myunderstanding  of this bit :  A Loose jet can drovn???  one cylinder ,and wash all lubrication  out ..so it wears faster than the rest.  drovn??  = possibly drain/drown

There may be something in that as the dome on the head and the top of the piston had whitish deposits on them. The other three were normal appearance for a 21k miler.

Looked at piston ring grooves last night and not excessively worn

 Unfortunately, I never got the original carbs with the bike to examine the jets.

[thirsty 1]

If the rod is bent the wear pattern in the cylinder may have a twist in it.

Nailed it or the pin bushing is worn prematurely.