Vespa malossi holed piston

[Nik221]

Hi all, i have been riding my vespa px malossi 210 around the city and has been great. I went to a rally not far but it was all motorway around 150 miles away. 10 miles to arrival my vespa holed a piston. Same thing happend on the way home with my old kit that i had sent over to me but a 100 miles away from home. I noticed that the cylinder cowl had melted both times. My main jet is 130 and i have a fast flow tap. It is a new malossi 210 sport only had 400 miles on it, with a mazzuchelli longstroke crank with a mmw head 10.8 compression and 1 mm base and 0.5 head gasket. I could hear rattling a lot but thought it was a bearing and it got worse as it got hotter. What should i do ? Cheers !

[Nik221]

Oh yes and a sip road 2.0 exhaust

[lockman69]

Rattling = Pinking ---What is your timing set at ?

[Nik221]

Around 17 btdc

[Spanish Fly]

Maybe the compression ratio is too high?
Do you know the combustion chamber volume?
Is it a genuine Malossi Head?

SF

[sean brady scooters]

firstly i would suggest timing of 16 BTDC ,and as suggested lower the compression ...also check for air leaks .
but most importantly i would advise that you get it set up on a dyno ..
you dont say what carb your running but fuel starvation on tuned vespas is a common prob especially on longer runs at higher speeds and when the tank level gets low !

[Nik221]

The car is a standard si 24.24 carb with a sip fastflow tap. The head is a MMW head.

[Nik221]

I have ordered a cosa float and a 2mm spacer for it aswell

[Nik221]

Should i put the timing on 18 or 16 ?

[Velo Merde]

You did not modified the carb? Second drilling on the needle-valve, 2mm drilling to the main-jet, ect...