I gotta tell ya, 125's wear out FAST, especially when they are raced. I have never gotten one to last longer than 2 years, and even then had to rebuild the motor (crank up) several times in the second year. My youngest is on his second year on his 2002, but since he was hurt part of last year, I am hoping to keep in going throughout the year. I already put a new motor (crank up) in last December, and will probably do it one more time in June just to be safe. Between rebuilds, I change the dry side seal monthly. Kawasaki said I was nuts, but this has worked to keep 125's together for more than just me, as I have shared this trick with lots of dad's whose son's ride 125's. Not sure why, but the dry side seal just does not last on the 125's.
I would recommend that you step your friend into a 250. The frame geometry is about the same, but the 250 is much more durable, and will cost a LOT less to keep running. You can also get into a 250 pretty cheap with the deals the factories are offering, as the used market is currently soft.
Just my $.02.
Rick
