Not a holed piston

[Muttley McLadd]

A few electrical problems and it stopped on the motorway at about 75mph..

Turns out it isn't a holed piston.
I was a bit concerned when I took the exhaust off and chunks of metal fell out of it.

The barrel might need a rebore too.

[soosh]

Whats this off?

[Muttley McLadd]

It's my 185.
It survived the Mille intact. This happened the first time I rode it to work after that.

It's been sitting in the garage, unwashed since then, waiting for inspiration.

[Rich_T]

OMG! did that lock the back wheel or did the rod and pin break free and do a wild thing, there must have been skid marks somewhere? Looks like the piston has softened with heat around the ring-land infront of the exhaust port first. Piston crown looks a bit grey so perhaps up your jetting both mid and main when you're running again. Were you on WOT at the time or had you rolled off a bit? What gearing/set up are you running?

The good news is the barrel does not look too bad at all, there looks to be a bit of damage at the front bottom edge of the transfer ports but I have seen GT barrels running with much much worse damage than that with no ill effcts. Depending on how deep the score marks are you might get away with a light hone. Unfortunately, I think the piston might just have had it.

[tonydevon]

chemical metal is your friend!

but your correct, your piston isnt hole

I never seen one like that.

most important is that you didnt suffer a get-off at 75, just your wallet thats taken a battering

[Muttley McLadd]

The barrel does have a bit of a chunk or two out of it. There's a few bigger pics of it of Loserbook, Rich.

It was WOT. To be fair.. it always is. And it does very well at it

No lock up. Felt just like a holed piston. That's why I've been in no rush to take it to bits.

Rebuild will certainly cost more than the last couple of bits for my TS engine.

[Rich_T]

spectacular break up! The barrel is fine for a re-bore, is the rod damaged at all, if the crank is OK you'll have got away very lightly.

I'd go up a couple of points on your main jet and atomiser it does look a bit warm on the crown and ultimately it is the softening piston that was the catalyst. It's pretty impressive failure, you can see from the distortion in the rings how the whole piston has slumped and distorted under the impact load right down it's length.

What was the gearing so I can take a stab at the rpm that all this let go at.

[Ian Hepworth]

there must have been skid marks somewhere?

I think we can hazard a guess where the skidmarks were.

[Muttley McLadd]

Rich, it was sitting at 7000 revs on 4.6 (17x46 on Li150).

But it did that every day for 30ks each way. Until the problems with the electrics and whatnot (high altitude and some s**t fuel on the Mille seemed to have a big effect on it), it's been flawless. I never ride covering the clutch. I'd have willingly taken SpecialX's challenge about holding a GT flat out until it runs out of fuel.

I should probably whip the crank out and clean it out. The crank has been in for six years. It could do with being replaced while it's in bits.

No skid marks. It didn't lock up.. just stopped. The scariest bit was having no lights. (six in the morning - pitch black)

[soosh]

I'd have willingly taken SpecialX's challenge about holding a GT flat out until it runs out of fuel.

Why,is that a no,no then? That's happened to me before and all was ok.