Hi Guys/Gals, I am a newbie to this forum. I am in my 60's, have a WR450, and an XT660R. I have been working through Mods to the 660, Have changed the air filters, and removed the duct from the air box. Have an Ohlins shock on the way?Have staintune Mufflers. Have a spare set of WR forks and Triples, has anybody tried these on a 660, with gold valves in them??? Also check the air box temp sensor, and found the resistance goes down, as the temp rises, so has a Negative Temp co-efficient, I used the variable resistor to set the right value, then replaced it with a fixed resistor!!! with regards to the Co2 sensor, these are only a Narrow band sensor, and vary from 0-1V and seeing as how the ECU thinks it is running Rich by averaging above 0.5v, so I know Kevs device is a voltage divider etc, but I cannot see why a resistor would not work to reduce the voltage below 0.5v, which would indicate to the ECU that it is Lean, The only thing that would affect the resistance would be Temp and current flow. They have used resistor ballasts in cars for decades??