Commonly known as 'little end knock' rather than 'big end knock'; both if which mean 'wear'. But I am surprised it has happened on a Ducati rather than the customary 'piston slap' - either a high mileage engine or a lubrication issue IMO.
Got it from Ducati: Piston only sold with cylinder; price £271.00 ex. Only vertical cylinder plus piston available. Horizontal discontinued.... requested to order two vertical cylinders to get a pair. I'm not going for that. And, are they flogging unbalanced pistons as a set of two. JEPistons only have 900 and 916 pistons as stock items. Custom pistons are £180 +VAT each, at most economical order of four pistons. Q Would a monster do, and up to what date...? That I need to know. Has to be from a 600cc - I must also consider an engine swap: what engines series including monsters would be easily swapped regarding mountings? - Advice most appreciated! I'll look for aftermarket suppliers, but not too confident from preliminary searches. Looks like it may be the end for many bikes, particularly 600cc, and this one...until aftermarket suppliers in Europe get in on the case for supersports. Any leads? I have a mounting horror at going onto ducati in this area of support... Probably a symptom of the demise of (expensive times for) family business (aka the obstructive-destructive globalist-cleptomaniac's hikes in overheads and tax). Maybe it'll find a pair in time though... yawn.
I'm puzzled about it, though - because normally when the little end (or the big end) fails, it is down to worn bearings ie, the bush in the con-rod (or the big end shells). The gudgeon pin should be a tight fit in the piston - normally assembled when the pin has been frozen and the piston warmed up. Why the actual piston has worn suggests to me that the pin was a loose fit in the first place, which simply isn't correct IMO. In the circumstances, I think I would also check the vertical cylinder out.
Right, agreed - its a convention; con rod bushes etc are made to be sacrificed, and following that, gudgeon pins to piston bosses. I have always found that to be the case in all British and Japanese bikes and cars I've come across (a few - not hundreds though (-: Good idea to check the other cylinder, yes a must.
I had a 2-stroke Bultaco Sherpa many years ago that made a noise I was assured was small end and was told not to worry about it. The sound was a metallic ringing sound but it wasn't a knock and only happened on the overrun, such as when blipping the throttle. It was a sort of rapid ring, ding, ding, ding, ding noise.
I guess you could read 'tapping noise' rather than 'knocking' for small end failure - but I have to say I have never had an engine where the gudgeon pin bosses in the piston had worn to the extent of the OPs piston. I would imagine it would be more pronounced than a tapping noise though.
smaller 2 strokes with small end noise are not as serious, it seems. Partly due to lubricartion in fuel, and also to the forces involved... We ran Suzuki GS 250s without failure for miles on end with slapping small ends, because the small ends were unbushed and wore away, recognised as a design fault. I said above conrod bushes are made to be sacrificed before gudgeon pins - actually , I haven't always found that to be the case... But certainly, true of gudgeon pins and pistons.
I have one more question, in order to plan rebuild: what generally was the scheme for balancing cranks/pistons etc on rollout of production SS's in those days of nineties?
When I rebuilt my motor, I had the crank/rods/pistons balanced by DTS - he said that it didn't really need doing, as it was pretty accurate out of the factory - will depend of course on which pistons you end up using Sent from my P01M using Tapatalk
I'm given to believe that the M600's 2003 change to 620 cc brought it to the same stroke = 81.5mm (and crank?). I could consider a monster 620 engine, could be useful. Not sure if that is a straight swap, or if the monster frame had changed by then.....
