The term "TCI" typically stands for "Transistorized Ignition System" in the context of motorcycles. It's a type of ignition system that uses transistors to control the ignition timing. However, it's important to note that the specific TCI used in the Bullet 350 motorcycle may be unique to Royal Enfield and may not have an exact equivalent from other brands.
Different motorcycle manufacturers may use different ignition systems and technologies, so it's not straightforward to find an exact match from another brand. Additionally, the compatibility of ignition systems between different brands can be challenging to determine without detailed technical information and expertise.
If you are experiencing issues with the TCI on your Bullet 350 or looking for an upgrade, I would recommend consulting with a professional motorcycle mechanic or contacting Royal Enfield directly for information about compatible aftermarket options or potential upgrades. They will be able to provide you with the most accurate information and guidance for your specific motorcycle model.