Where does the lambda O2 sensor install on the motorcyle?

The lambda O2 sensor installs into the exhaust system where a bung has been installed either by the exhaust manufacturer or by user if needed. The bung is a metric M18 x 1.5 threaded that is found near the swingarm or footpeg area of the exhaust piping. Major aftermarket exhaust manufacturers such as Yoshimura and Akrapovic have this installed in their Stainless or Titanium systems. Please check with your vendor or manufacturer of the exhaust you are thinking of buying to make sure this is installed. If you need to install one you can have it welded in place at a reputable welding shop that can do TIG welding of the Stainless ones. The Titanium bung is much more tricky to weld in as an experienced welder with Titanium is needed and a chamber to have an environment free from contaminated air while welding. It would be best to contact the exhaust manufacturer of a Titanium system to have them install the Titanium bung in place with their well equipped shop or production facilities. We plan to add bungs for sale in both Stainless and Titanium, but they can be found with a Google search on the internet. Eventually we will publish a list of businesses to weld in the bungs also.

Where can I weld a lambda sensor bung on the exhaust system?

The placement of the O2 sensor is not very critical. It is a heated sensor and its temperature is controlled by the AFR Tuner, so it will adapt to the placement between wide limits. If the sensor is anywhere on the collector pipe near the footpeg then it will be fine. Motorcycle exhausts are too short for overcooling to be a problem and overheating is unlikely to be an issue on naturally aspirated engines.