If it helps......for the little tacker, I would go with the PW50 over the TTR. Heaps lighter and they don't have any engine braking...It's a long story, but I watched two kids learn together one on a PW the other TTR, they both ended up picking it up quicker on the PW and neither wanted to ride the TTR.
The older aircooled KTM 50's would also be a good one.