Thanks Uli, I'll wait for your reply.
Peter, thankyou, I'm kind of stuck on that bit about contents as it specifically doesn't seem to confirm the piston question.
It's usual to replace a piston and bore liner on these motors and they are sold separately at approx the same cost for the complete engine, so that's what is confusing me as I can't be certain that it is included in this assembly.
My son's one has a failed piston which we have either to replace or renew the whole motor, I didn't want to end up with two motors and no pistons hence the need to clarify.
If it's all included I can go ahead and order.