RM100   Kit includes
1 head body, 2 domes, 1 o-ring kit
5 acorn nuts, 5 copper washers

Order your kit from parts listed below

2003-2010 Head body

OS12 o-ring kit fits all years

Dome selection (see note)
K40 or W40 6.9cc
K41 or W41 6.4cc
K42 or W42 6.0cc
K43 or W43 5.6cc

Note
Heads colors are red, blue, black, gold and aluminum
K40 dome is closest to stock compression for the RM100 these domes use o-ring seal, the max bore is 52.5mm. The W4 series domes have no o-ring groove use head gasket the max bore 54.5mm. The 54.5mm motor is somewhat unreliable and frequent head gasket replacments should be expected.
54.5mm Big bore head gasket kit optional
Dome modification for big bore available see FAQavailable see FAQ