A motorcycle comes around the corner and your dog barks or lunges. The sound and movement arrive together, with little warning. The first job is traffic safety, not asking for silence. Keep a secure, well-fitting harness and a standard lead you can hold. Move behind a barrier or turn onto a quieter street if there is space to do so safely. Never use a long line beside a road.
If your dog could pull you into traffic, stop using that route until you have in-person help from a qualified, reward-based trainer. A new or severe sound reaction warrants a veterinary discussion too. Do not deliberately stand beside passing motorcycles to "desensitize" your dog, being overwhelmed can make the next encounter harder.
Find the workable distance
Start with a route where motorcycles are occasional and can be seen or heard at a distance. Before your dog reacts, reward them for noticing one and turning back toward you. Then leave. Practice a cheerful U-turn on ordinary walks so it is familiar when a bike appears suddenly. If your dog cannot eat, freezes, or barks continuously, move farther away next time.
You may not control when a motorcycle passes. Choose timing and route to reduce surprises, and build the skill away from traffic before asking for more. For dogs frightened by noise, a veterinarian or behavior professional can guide a gradual sound plan suited to that dog's level of fear.
A successful walk might be a shorter loop on a quieter block. That still counts. If sound is part of the problem, see the noise-fear guide for planning practice away from traffic, a secure lead and a safer route come first
Sources: Dogs Trust: Reactive dogs - why it happens and how to help. VCA Animal Hospitals: Fear of Noises in Dogs.