Zero Motorcycles, Inc. (Zero) is recalling certain model year 2014 Zero SR motorcycles manufactured 30 December 2013 through 20 February 20 2014; MY 2014 Zero S motorcycles manufactured 36 December 2013 through 18 February 2014; Zero DS motorcycles manufactured 24 January 2013 through 4 February 2014; and MY 2014 Zero FX motorcycles manufactured 14 January 2014 through 27 January 2014. Due to a possible manufacturing defect, the motor rotor may contact the stator while riding, causing the motor to seize, locking up the rear wheel and increasing the risk of a crash.
On 24 February 2014, Zero Motorcycles was notified of a motor lockup on a 2014 Model Year SR motorcycle, which was being ridden aggressively at top speed by an expert rider on a race track in Australia. This event did not conclude in either an accident or injury. However, since this was a highly unexpected failure, on the same day, Zero Engineering obtained a production motor from inventory and was able to reproduce the failure on a motor dyno test at sustained max rpm and temperature (extreme durability test).
Zero Motorcycles issued an internal Stop Ship to investigate this situation further. The company tested additional motor samples were tested, with similar results obtained on a portion of the tested population. Zero developed a screening test to ensure the integrity of motors moving forward.
As of 10 March, neither the motor manufacturer nor Zero has determined the exact nature of the manufacturing defect that is the root cause of these unexpected failures. Both teams continue to investigate this situation and will continue with 100% motor screening for the foreseeable future.
Zero will notify owners, and dealers will test the motor and if it fails testing, replace it free of charge. The recall is expected to begin in April 2014.