torch
Well-known member
The Barbarian Jumper Mod is a hardware mod that relocates (or adds) a jumper between two terminals of the ECU, unlocking the onboard idle fuel mixture adjustment, as is possible in the European and Australasian versions. The possibility was the subject of much discussion when these bikes hit North American shores and we discovered Yamaha had disabled that function in ours.
Many, many, many people experimented with it after the jumper was reverse-engineered and the general consensus was that increasing the factory "CO" value by between 5 and 7 points on each cylinder produced the best results, fattening the emissions-mandated lean setting just enough to help the off-idle performance and smoothness. It doesn't really do anything at higher RPM, or when the O2 sensor(s) warm up enough to put the system in closed loop mode.
Yamaha soon learned what we were up to, and made a few half-hearted attempts to foil us. On the later Gen 1 models, they stopped supplying the wire, on the Gen 2 they changed the pin locations. But the community quickly figured out the details almost as fast as the changes were made.
Why Barbarian? I named it primarily in honour of Tom Barber, who first noticed the odd wire in the European wiring schematic. But remember that in 2002, we had to plunk down a deposit, order the bike sight unseen and be happy with what Mother Yamaha decided to eventually deliver. As I mapped out the pin functions with a scope one cold winter night in an unheated garage, I was inspired by the sense of overcoming arbitrary rules -- we were Barbarians at the gates of civilization, hacking the expensive machines we waited so long to own.
