If you're looking for a 270cc Go-Kart in Mumbai, I found several karting venues, but I couldn't verify from current public listings that they sell 270cc Go-Karts.
For a 270cc petrol Go-Kart, typical commercial models use a 4-stroke engine, chain drive and disc/hydraulic braking; specifications vary significantly by manufacturer.
For a manufacturer option, you can consider Rajleela Industries - Electric Golf Cart | GO Cart | Cargo Vehicle Manufacturer in Pune | MH | India, which is based near Pune and manufactures Go-Karts and other recreational vehicles.
If your requirement is specifically “270cc Go-Kart for a commercial racing track in Mumbai”, I can help you compare suitable specifications and prepare a product description for Rajleela Industries.