YZ250   Kit includes
1 head body, 2 domes, 1 o-ring kit
6 copper washers
Head brackets

Order your kit from parts listed below

1992-1998 Head body
1999-2010 Head body

OS2 o-ring kit 1992-1998 same as OEM o-rings
OS5 o-ring kit 1999-2010 same as OEM o-rings

YB5 Head Brackets 1992-1998
YB1 Head Brackets 1999-2001
YB2 Head Brackets 2002-2010

Dome selection 1992-1998
Y31 21.6cc
Y32 20.2cc
Y33 19.2cc
Y34 18.6cc

Dome selection 1999-2010
Y21 21.1cc
Y22 20.1cc
Y23 19.1cc
Y24 18.4cc

Note
Heads colors are red, blue, black, gold and aluminum
Y31 domes are closest to stock compression for 1992-1998
Y21 domes are closest to stock compression for 1999-2010
Y3 series domes the max bore is 72.mm
Y2 series domes the max bore is 68.5mm
Dome modification for big bore available see FAQ