Metallurgists

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Not easy with these photos I admit. I did not take them and the actual chain has been returned to Kawasaki.

But what was the cause of this failure do members think.?

Story is that it's the chain of a Kawasaki ZZR 1400 Performance sport edition that has just 1200 miles on the clock and was serviced by the dealership at 600. And yes he has kept the chain lubricated.

My mate had been out on it the other week one evening and by his own admission had been giving it some stick. - But then close to home on a dual carriageway cruising at about 50 in top gear the chain let go. - Anyone that knows anything about bikes realises that a snapped chain can very often result in a very serious accident. Very, very fortunately and unusually it came off clean and this was avoided.

The dealership did not want to know and told him he must have been riding it too hard.!!! His argument to them was basically. "Sell me a bike with 200bhp and of course I am going to ride it hard. It's what they have been designed to do. And that a chain with such low mileage on it should have caused the tyre to break traction long before it snapped."

Argument progresses over several days with the dealership not giving ground. ............. So he contacts Kawasaki themselves. They present a totally different attitude and show great concern that if they have bikes snapping chains they need to know about it and investigate the cause. They contact the dealership and tell them to fit new chain and sprockets pronto FOC and send the offending chain to them.

They eventually do as told and return his bike to him 2 weeks later with a damaged front mud guard. - But that is a different story that they then also had to sort out. As you can imagine he is less than a happy chappy with that dealership even more so considering he buys a brand new bike every 2 - 3 years.

But what to the guys here think has caused the failure. Not easy I know without looking at the actual chain. I should add that it was also not the 'soft link' that failed.

Nick

Well it's hard to tell from the photo with nothing to give scale, but that chain does not look very beefy for a 200hp bike. I've fitted DID or RK heavy series X-ring chains to bikes with half that horsepower that appeared to have heavier sideplates than that chain.

Would be worth a closer look at the two break points.

I would doubt if they broke at the same time.

One will be a different colour to the other.

One will be a 'clean' crack , the other will be torn apart.

This may give you a clue as to how long it had been running with a fault before the hard acceleration finished it off.

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He was not accelerating hard when it gave way. (he would have told me the truth) But even if he was that is not the point really.

I should add that with these bikes you cannot just slam the power in and it be delivered instantly through the drive train and to the back wheel. The electronics will not allow you to do this when set. They have traction control and anti 'wheelie' sensors fitted. But these can be switched off.

Without these they would be virtually unrideable on normal roads to all but the very experienced. That may sound as if it's taking some of the point of these machines away. But even when fitted they will still hit 0 - 200 mph in under 10 seconds.

Nick

I agree with JH regarding the need for close inspection of the breaks ... but I aso wonder if anyone has looked at the sprockets.

I would not be surprised to find evidence of a small stone, or some other highway debris, being trapped between sprocket and chain.

MichaelG.

Edited By Michael Gilligan on 29/05/2017 13:31:02

No doubt that's why Kwakky asked for the sprockets as well as the chain?

Crystalline fracture, these links are mass heat treated and maybe very close to their limit and size. Then the pins are interference fit to the links and maybe this one was a bit hard? Ergo, cracking until extreme stress occurs.

Clive

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[quote]

They contact the dealership and tell them to fit new chain and sprockets pronto FOC and send the offending chain to them.

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I've had this happen once with a Regina Gold chain but never on a road bike, the chain went back it eventually came back with the explanation that the chain was run over tight, I doubted this so checked and they where probably correct, after thinking on this for a while I realised this happened during heavy acceleration but was more than likely caused a little earlier (about 100yrds) because the suspension bottomed out after the jump at Cadwell park, this tends to happen more on motocross bikes for the same reason.

My suspicion is this chain was adjusted too tight at some point and it simply failed later, dealers are notorious for not doing what they are paid to do, as for the 200hp these are more or less irrelevant figures, on a dyno these bikes can produce close to these figures but in the real world never do, traction control anti wheelie, and manufacturers in built restriction in all but top gear simply stop this happening, I've made parts for and ridden several WSB race bikes (not in anger I must add), for Yamaha and more recently BMW none of which produced 200bhp in rider trim, they are simply mind blowing things to ride, don't get me wrong, they can produce more than 200 bhp but the riders find it unmanageable and just end up going slower as a result, and when you look at the data logs from the bike rarely do they use full throttle, this will be apparent in the next few weeks as the TT unfolds, some riders go faster on the 600's as opposed to the superbikes.

Friend had a new super bike and the Alternator failed within a month of being brand new. Dealer said He flogged it too much. Only $300.

First tell us make of bike and name of dealer. They don't like negative publicity. As long as what you say is true it cannot be libelous. Ask dealer to explain link between engine power output and load on alternator. There isn't one. Then contact manufacturer, then go to small claims court

10,000rpm clutch drop?

Mike

I once had to contact manufacturer in Japan before UK dealership would help with parts. UK branch of manufacturer could not do enough for me after that one contact. Japanese do not like contemplating "loss of face".

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Nope.

Besides the slipper clutch should have taken care of it.

Nick

Carl Wilson - Fretting , in a low-hours, well lubed chain? I doubt it.

The other proposed theories above, ie a) small rock or other debris between chain and sprocket, b) bad heat treat of the link, or c) chain over-tight and then exposed to a hard stretch during a "landing" after "getting some air" are much more likely.

It's no joke when one breaks, I survived a bad crash when I was 18 on a custom 750 cc 4 cyl Suzuki due to broken chain/ jammed rear wheel / gravel rash at 80 mph. JD

Serious answer this time, I could imagine a manufacturing flaw in the material may be responsible. A friend had a fishplate break on his 900 Ducati which rotated and cut through the gearbox casing. He did not abuse the bike but was a quick rider. I would suspect that crack testing is not a part of the manufacturing process but may be part of the sample inspection routine. I have seen flaws in steel that cannot be seen but show up during working. Not good if it is a fault of that nature on a motorcycle where the failure could be catastrophic to machine and rider. It amazes me how much a good metallurgist can find out about a failure so if the part has been returned for analysis the report should be interesting if they share it.

Mike

Haven't had time to read all the posts, so apologies if I'm repeating.

I would check the sprockets for indentation or other damage from a foreign object - it's unlikely to be a road stone as they're pretty soft but I'd go with the damage caused prior by over tightening then it was an accident waiting to happen.

Sounds like rider and engine casing are largely unscathed, I hope that's an accurate assumption and all is well.

We only played with Mr Muir's stuff pre season when they are all spare, and only to test fit parts...

One last observation.

Look at the two 'colours' at the end of the pin which holds the two outer plates together.

Bright metal nearest the camera, blue oxide on the other side of the pin.

Normally , this pin is swaged into the outer plate and does not move. The roller does all the moving round

the pin.

But, the bright bit suggests a fair bit of movement took place between the outer plate and the pin.

Like might have happened if it had been cracked for a little while.