Most JE shelf pistons include double spiro locks as standard equipment. These locks are installed by spreading the lock between 1/8" and 1/4" and rotating the lock into the groove in the piston pin boss. Wire locks are installed in much the same manner but require chamfered wrist pins. Wire locks tend to spread side loads over more of the piston pin boss area and are considered to be a stronger method of holding the pin in place. Hook wire locks have a built in hook at the end gap. The purose for this style of wire lock is to prevent rotation within the lock groove itself. Tru arc locks fall between these two and can be used with the stock sharp edge wrist pins. The advantage of tru-arc locks is ease of installation and they can be re-used unlike spiro locks, however they are not recommended for medium to high horsepower applications.

This Part Fits:

Year	Make	Model	Submodel
2007-2012	Honda	CRF150R	Base
2004-2015	Honda	CRF250R	Base
2004-2017	Honda	CRF250X	Base
2014-2015	Husqvarna	FC250	Base
2004-2014	Kawasaki	KX250F	Base
2005-2015	KTM	250 SX-F	Base
2007-2013	KTM	250 XC-F	Base
2007-2013	KTM	250 XCF-W	Base
2001-2013,2015-2017	Yamaha	WR250F	Base
2001-2018	Yamaha	YZ250F	Base
2015-2019	Yamaha	YZ250FX	Base

Mahle MS Heavy Duty .990in 171g Pin