Holed Piston, Any Ideas Why?

[soulsurfer]

I initially took it to fit an Agusto box and set up with the dyno in the hope that the 700 degree heat spike could be sorted. In the process of setting up the Agusto a new flywheel was fitted and the timing checked thoroughly. It was taken back a second time and my concerns repeated. The heat spike never did get sorted but explained as possibly heat in the pipe and not to worry about it as on the dyno there wasn't an issue, it was after this that I didn't worry about the heat spike and that's when it went.

I'm now trying to identify the cause, if I can. If not, then I hope the rebuild of the top end will eliminate it together with switching back from the TMX30 to a TMX35.

I have now made arrangements with the dealer regarding rebuilding and setting up costs.

[drunkmunkey6969]

I keep all customers charts on file, so i can recall the info later if needed............it might be worth asking your guys to pull the chart up and give you a copy of the AF reading.

[tony]

Not good running that high mate. You need a good dyno operator to get the motor to work properly. Now if you can rule out crap fuel and can guarantee that motor was built right with no leaks then the issue is either to hi a compression or simply bad set up either mixture and/or timing. I take it you werent flat out in top at the time? The answer to this will eliminate another possible cause.

[J1MS]

If Aluminium has a low melting point of around 650 degrees centigrade and you had told the guy doing the dyno that it had spiked up to 700 wasnt he a little concerned, as even if its just heat in the front pipe, some of that heat is drawn back into the cylinder If the pipe is doing its job of scavanging the cylinder... Myself I wouldnt want to see over 650 degrees at any time on the EGT gauge even if it was explained away by elevated temperatures in the exhaust... 600-620 would be about right for a maximum if ridden hard I would think... Would any of the Knowledgable racers on here that run these EGT's confirm my thoughts or am I a mile out as usual...??

[soulsurfer]

Not good running that high mate. You need a good dyno operator to get the motor to work properly. Now if you can rule out crap fuel and can guarantee that motor was built right with no leaks then the issue is either to hi a compression or simply bad set up either mixture and/or timing. I take it you werent flat out in top at the time? The answer to this will eliminate another possible cause.

The cylinder head measured 23/24cc but protruding spark plug is a concern and is being replaced with a AF head.

I wasn't flat out, just cruising 6-6.5k rpm, what are you eliminating here?

[tony]

Under load (ie on the road) the motor will use a lot more fuel than on a dyno. So I was trying to see if there was a flow issue. I've only seen one operator use a dyno in a manner that will replicate road riding..even then a calculation was required for wind drag.

[drunkmunkey6969]

I've only seen one operator use a dyno in a manner that will replicate road riding...

Can you expand?

[sean brady scooters]

brake loading.............

[J1MS]

Could have been aplying a little back brake to load the engine giving a power drop in real terms just a guess... could be a mile out yet again..! Sean you beat me !!!

[sean brady scooters]

the brake is attached to the dyno.....................usually a disc brake of course....................
it adds extra load over and above roller weight............
under hard acceleration or say up hill motors require a much richer mixture.............