The motorcycle can't get into the 1.2.3 gear, but what happened to the fourth gear?

There may be a problem with the positioning device of the shift arm, shift hook and transmission drum on the right side of the transmission drum. Open the right engine cover for inspection, and the gear teeth and fork will generally be fine.

The engine installed in your car has a four-gear protection function, and you can only shift from four wheels to first gear after parking, which is not possible when driving. The purpose of this design is to prevent the danger from changing from fourth gear to neutral gear and then to first gear after misoperation, and also to prevent the bad operating habits of neutral landslide, mainly for safety.

As long as the car stops, you can change from fourth gear to first gear. This function is realized by the limit plate on the fourth gear of the countershaft.