Motorcycles are depressing.

If the speed drops by only 50-60 yards, it should still be a carburetor problem, such as improper mixing ratio, low oil level, improper position of the main oil needle or slight blockage of the main metering hole, and problems with the throttle diaphragm. This failure may occur if the air filter is poorly ventilated. If it's a circuit problem, it won't just drop in 50-60 yards, and there are few problems with the igniter and high-voltage bag of Diamond Leopard, so you can check it.