GasGas 50SM Q:

[slocalspode]

I know the GasGas EC50SM is kind of a rare bird here in the USA. I am
hopping someone might have the answer to my question.
I am trying to find out who makes the motor for the GasGas 50cc bikes.
Is it GasGas? Or Minerelli, Piaggio, Polini. I know it is not the same motor
that I have in my Derbi Senda 50SM.
A friend of mine has the bike and we have been unable to find a "Big Bore"
kit for it. I know GasGas makes cylinders and pistons for their 65cc MX
and 80cc trials bikes. And I think they used to make a 70cc trials cylinder too.
I would assume the trials cylinder port timming would not be "sporty" enough
for a street SuperMoto like the EC50SM. Am I wrong? Is the high RPM
performance gained from the pipe used, or the port timming. If so. Would the
top end from the TXT80 fit the bottom of the SM50 motor? Or is there an
aftermarket performance kit available for these bikes? Like a Hebo or
Malossi or MK.
Thanks for any clues to my search.
Jeff in So. Cal.