Bang goes my engine.

[(RIP) Kaister]

Probably the timing chain. my XChallenge did this when it was new, then the tensioner moved on a click or 2 and it quietend down.

Sorry to hear about your bike gunz.

Looks like the piston may have flipped in the bore- something some of the early crf mx bikes were rumoured to suffer.Mostly down to these short skirted pistons not having the vertical stability of a longer skirt.

Looks like it has flipped and the piston crown has taken out the plug (where it is cracked), while the conrod has sheared off the gudgeon pin castings on the underside of the piston as it has come up and hit the cylinder head/plug, and with the flipped piston making the whole assembly much longer, something had to give- which is the gudgeon pin castings on the bottom of the piston.

good luck with getting it sorted.

flipped ? ?

you're not sure what you're saying are you ?

 

[austen_gs]

.

Looks like it has flipped and the piston crown has taken out the plug (where it is cracked), while the conrod has sheared off the gudgeon pin castings on the underside of the piston as it has come up and hit the cylinder head/plug, and with the flipped piston making the whole assembly much longer, something had to give- which is the gudgeon pin castings on the bottom of the piston.

That seems like a plausible sequence of events to me, looking at the damage. But then what would cause it be able to rotate the amount required to hit the the top end?? I wonder if the piston rings could have started breaking up inducing piston slap, which progressed far enough to allow the piston to rotate enough to impact the head? I cant imagine just a worn bore allowing enough slap for piston to rotate and still be running without a noticeable drop in power

 

[(RIP) Kaister]

have you tried rotating a tight fitting cylinder in a hole ?

you're talking shite - pistons DO NOT FLIP !!!!

 

[v8legend]

have you tried rotating a tight fitting cylinder in a hole ?

you're talking shite - pistons DO NOT FLIP !!!!

+1

I'm not sure where this originates from? Sounds like sticky fingers on the tinterweb.

I can see how a piston crown that has let go can be smashed to hell. But to flip in the bore, come on.

 

[v8legend]

have you tried rotating a tight fitting cylinder in a hole ?

you're talking shite - pistons DO NOT FLIP !!!!

Oh yeh. That piston has to rotate 180 degrees perfectly before being hit again. Have you watched the video. The piston doesn't seem to have incurred any more damage after letting go. It certainly hasn't been bashed by a conrod and gudgeon pin.

 

[(RIP) Kaister]

Oh yeh. That piston has to rotate 180 degrees perfectly before being hit again. Have you watched the video. The piston doesn't seem to have incurred any more damage after letting go. It certainly hasn't been bashed by a conrod and gudgeon pin.

i used to do this shit all day long...fob customers off with bullshit speak in the vain hope of saving the dealer a few quid - that is.

See my original post - the design is faulty - the piston has split, then been pummelled by the con rod and probably the valves - after that its anyone guess what has happened - usually total carnage.

however, i have rebuilt engines in a much worse state than this

 

[v8legend]

Has anyone heard how Paddy's getting on?

 

[argee]

Taken back to the mothership....?

 

[vanrouge]

any chance of an update on this one gunz

 

[v8legend]

any chance of an update on this one gunz

From what I gather, the engine is due in this week. Paddy will update us when he can.