The Yamaha YZF-R1 can have some serious problems with the gearbox. In affected motorcycles, both second gear wheel and pinion gears in the transmission may break as a result of extremely high stress and/or improper down-shifting. This is due to inadequate component strength.
In addition, the third and fourth gears may be deformed or break as a result of excessive stress caused by hard usage. If gears fail, the transmission could lock up, causing loss of control.
At the moment Yamaha Thailand has not issued a recall for the YZF-R1 and they're said to look into the problem if any motorcycles in Thailand are from production that has used the inadequate components.