Fit For Black Stem Seals For Zongshen NC250 250cc For KAYO Dirt Bike Motorcycle Spare Parts Fit For Zongshen NC250 ZS177MM 250cc engines on For KAYO offroad dirt bikes black rubber with delivers Tight sealing lip stops oil leakage to eliminate excess oil burn Blocks carbon dust to slow stem abrasion extend train lifespan Full stem seal kit supports simple cylinder head overhaul replacement