M8 heads for sale!!16 Aug, 2018 in Head Hoggers tagged harley 4 valve heads / harley 4 valve porting / harley bore and hone / harley case service / harley engine machining / harley machine shop / harley performace / Head Hoggers / M8 builds / M8 kits / Milwaukee 8 heads / motorcycle mobile dyno by headhoggers (updated 2813 days ago) These are WATER cooled heads. They are our stage 3 M8 head. Oversized 41.4mm intake valves/ 32.10mm exhaust valves, new guides, seals and woods M8 valve springs. Fully ported and ready to go!! $1500.00 no cores needed. Let me know.