Having had a chat with Yamaha UK, the tech guy said i need to connect to throttle via the three wires (Y, BL, B i think) which still seems straightforward. But the block connectors on the engine connect to the gauges directly also using a block connector, the price for these harnesses seem crazy.
Are you trying to connect a tacho (rev counter) to a yamaha engine that is already wired up to a 703 control box with a wiring loom? i.e. with key start and kill cord etc connected. On mine (and its bottom of the range in terms of size / fancy electronics - so I assume all models) there were 4 (i think) wires coming out the control box. Its possible if these weren't in use that they have just been tucked inside the control box. Hooking them up to the tacho is trivial... search the forum for the colour codes as I have posted it before.
ok great wilco. The throttle power connex seem fine, and the only complication to engine is that the gauge could be older than the engine, ie may need 2 into one block connector, thanks for replying.
