hair line line in front mudgaurd!

[Winston Smith]

Even if there were a 'seam' it would only be where the mould joined if that was the production method,

It wouldn't be weak at such a point as it wouldn't have been 'joined'.

It was always the urban myth that polycarbonate helmets were joined together and were weak on the seam.  It was just where the mould split to get the full shell out.

I imagine the mudguard is injection moulded and comes out 'in one'

[2kwacks]

..I imagine the mudguard is injection moulded and comes out 'in one'  this would appear to be the case due to be there being no join. if the split was to the side or off centre then I wouldn't of botherd even claiming a warranty replacement. it's just coincidental that the split is from the very tip and "dead" in the middel with no signs of damaged. whats baffling me  is.. there's no stone damaged, the front wheel as never been removed, I'm the only one who rides and cleans the bike so I can't for the life of me think how this split as occurred. but suppose  happens and under the circumstances I think kawasaki offering a 50% discount is fair enough.

[Winston Smith]

 

Still a shitter though.

[Boomer]

A perfect straight line, exactly in the middle of the mudguard?
I think you will find that for that to happen, the mudguard is probably moulded in 2 halves which are then welded together.
This is common practice for many such parts as releasing complex shaped parts from injection moulds can be difficult.
In 2Kwacks case the weld didn't take and was probably held together by the paint.
The vibration of use has just caused the paint to weaken and the crack to show.
I can't say for certain until I see the mudguard but this is the most likely explanation.