Holed Piston, Any Ideas Why?

[tony]

Hi mate.. if you had a problem with a 'heat spike' with static ignition then there was a fault there already that needed addressing ,as you said it was mid range and not flat out where the problem was. If the 'spike' was say at 6000 approx only but ok say at 8000 then this says to me the augusto wont help you as with the static ignition you are still keeping the heat and the motor was ok.

[soulsurfer]

I had no spike with a TMX35, it ran cooler.

I didn't have the Agusto fitted to cure the spike, that was a separate issue.

I'm thinking that this heat spike may have been gnawing away at my piston, but backing of or accelerating through it had saved it and that by eventually holding the motor at that level then attacked it and took it's toll???

[drunkmunkey6969]

Yup, i'd agree....its sounds like the problems started when you changed your carb from a 35mm to a 30mm.

If the heat spike wasnt there with the 35mm and then appeared with the 30mm, it sounds like the 30mm wasn't jetted right to begin with.

As you say....when in the lean spot, it will have been gradually gnawing away at the piston....but never quite blowing as you throttled out of the lean spot to cool.....but eventually you held it too long.....and it blew.

Would that theory stack up?

No idea why the lean spot didnt show on the operators A/F graph though.....if its lean enough to hole a piston, it should show up on the graph?

[Matty]

How did it run when you first got the engine?

[soulsurfer]

How did it run when you first got the engine?

Fine, it was built for me a few years ago. Why?

[Matty]

How did it run when you first got the engine?

Fine, it was built for me a few years ago. Why?

An obvious question but if it ran fine, then why tinker with it? It appears that you've got all manner of problems now.

[soulsurfer]

AAh, a trick question

Inherant disposition of a Lambretta owner, born to tinker to see if can be improved

[Matty]

Inherant disposition of a Lambretta owner, born to tinker to see if can be improved

I hope you improve it further than a holed piston fella.

[J1MS]

Have you made up your mind yet Soulsurfer, for the probable cause of the total melt down of the piston...?

I think Tony and Sean have come up with some very valid points that could well have caused this disaster, I really do hope you find the cause and identify it, so its avoided by anyone else in the future... Wish you all the best luck...

[156 D]

AAh, a trick question

Inherant disposition of a Lambretta owner, born to tinker to see if can be improved

When i was younger i had a disease called "Preventative Maintenance".... ....i used to be under the car in the pouring rain just to see if a nut had come loose....it hadn`t.. ..i was always tinkering with mixture screws....i came back to the same setting.. ..and so it goes on.....If it works ok then leave it alone....i am now only a prisoner of the friendly yellow duster with a bit of Turtle Wax, at least it is cleaner that when i started!!.......... :bouncing: :smug: :bouncing: