The HPI Flux EMH-3S Brushless electronic speed controller (ESC) is designed primarily for 1/10 scale RC vehicles, whether on-road or off-road, with a DC current capacity of 80A and waterproof protection against dust and water. Regarding compatibility with your Reely Dirtbike Brushless WP10BL50RTR 1:4, it's important to note that this controller is specifically designed for 1/10 models, which means it may not be directly suitable for a 1/4 motorbike due to differences in scale, power and connectivity.

There is no explicit information indicating that this ESC is compatible with 1/4 RC motorbikes such as the Reely Dirtbike. If you want to make a change, you'll need to check that the electrical specifications (voltage, current, connectors) match those of your bike. Without precise confirmation, it is likely that this ESC is not directly compatible with your 1:4 RC motorbike.

I advise you to consult your bike's manual or contact the manufacturer to confirm compatibility before replacing with this model of HPI ESC.