Scooterotica

isnt the melting round the edges caused by debris from the holed piston travelling up the transfer ports and becoming trapped between the head causing localised overheating here

the exhaust side seems clear

soulsurfer wrote: It had just been dynoed and with EGT guage a 700 degC spike at this speed which, on a TMX30, I tried to jet out without success.

Can you post the Air/Fuel graph?

drunkmunkey6969 wrote:

soulsurfer wrote: It had just been dynoed and with EGT guage a 700 degC spike at this speed which, on a TMX30, I tried to jet out without success.

Can you post the Air/Fuel graph?

No, I didn't get a copy, but I saw the screen in real time. The spike didn't show up on the dyno, only on the road

At what revs did the engine make peak power on the Dyno..?? and at what revs would you have been riding it at when it popped..??

i would guess at between 5...........6000 revs..............depending on gearing

sean brady scooters wrote:i would guess at between 5...........6000 revs..............depending on gearing

So if riding at this say 6000 rpm, where the strongest pressure wave returning from the exhaust would increase the chances of it detonating, more so if there was an already underlying problem... Maybe.??

J1MS wrote:At what revs did the engine make peak power on the Dyno..?? and at what revs would you have been riding it at when it popped..??

Peak power was 21.27bhp at 7500rpm. Gearing is LI150, 16x47 rpm at the time would have been around 6500rpm.

Was it ok before you went to the Dyno, did they change anything. Seems starnge that after going there it went wrong.

Worth checking the ignition advance against what you think it should have been..........

soulsurfer wrote:

J1MS wrote:At what revs did the engine make peak power on the Dyno..?? and at what revs would you have been riding it at when it popped..??

Peak power was 21.27bhp at 7500rpm. Gearing is LI150, 16x47 rpm at the time would have been around 6500rpm.

Forget that then.... Maybe the ignition might be somthing to check, as Avantone says.... but it may still be a combination of more than one thing which makes finding the cause of this melt down a little tricky... have you managed to get a full print out yet from the dyno..??