EE's right. Yamaha had issues with piston life on the 250G with it's cavernous intake ports.
Just thinking out loud, but since we are now off topic, might I suggest an RZ motor in that frame with say a stroker crank and CPI cylinder for about twice as much power as a TZ top end.
Just thinking out loud, but since we are now off topic, might I suggest an RZ motor in that frame with say a stroker crank and CPI cylinder for about twice as much power as a TZ top end.