[dhgeyer]

For starters the TU has only 2 valves, whereas the GZ has 4. The cylinders look quite a bit different. The tank is different, and the TU has no fuel shut off valve, since it has a fuel pump instead. I suppose you could just rig a line to the fuel pump from the the valve on the GZ and leave it on PRIME all the time. So, at a minimum you would need to buy the fuel pump, the throttle body with injector and TPS (throttle position sensor), and an ECU (electronic control unit). You would have to hope that the connections from the TU's throttle body is consistent with the ones on the GZ's carburator, going to the engine and the airbox, and that the new components would fit in the shorter GZ frame. And, along with the different valve setup and different airbox and filter, you would have to hope the ECU would be able to function at all in the different environment. Might need a different throttle cable. The TU has a catalytic converter, and is a closed loop EFI system, complete with an O2 sensor. The EFI probably wouldn't work properly without the input from the O2 sensor, so you'd have to somehow rig a TU exhaust system to the GZ, or else rig up some electronics to mimic the input from the O2 sensor. People actually have done this to some of the early oilhead Beemers because some of them ran very badly from the factory, and it was discovered that taking the real O2 sensor out of the loop and mimicing its input solved the problem. Way over my head electronically. If you tried to rig a TU exhaust to the GZ you would need to deal with the fact that the GZ has a 2 into 1 system, whereas the TU has a single pipe from the head, and it's a larger diameter. Then you would have to hope that the ignition control in the TU's ECU would properly control the ignition on the GZ, with correct timing and so forth. Probably wind up needing a TU ignition setup right out to the spark plug wire.

When all is said and done, I think it would be easier to just buy a TU250. I'm pretty sure there is one in my (hopefully) not too distant future. I'd trade up tomorrow, but I have this problem. My daughter, who rides, has fallen totally in love with the GZ. I bring up the TU once in a while, but she insists that she's "not ready to break up" with the GZ yet. Like it's a friggin boyfriend or something! Anyway, I can't break her heart, so the GZ stays for a while. Can't see the TU and the GZ along with 2 other bikes, so I'm stuck for now. Damn!