Hello all! Been 3+ years since I picked up a U-Force 2013 800. Thanks showing me the way to get a manual! Because of many issues at home I'm just posting about it! No compression one #1 cylinder, took off the valve cover and found the rocker arm shaft bearing bosses ( right word?) completely broken in half opposite the gear. replaced the head and drove it about 1K miles. Stopped on the trail, no noises, no warning, just stopped! No compression on #1 with same exact problem! I can't imagine what could cause this this! Not ridden hard, clean oil, no overheating, I'm baffled! Anyone on here experience this! Help! Thanks!

[2015 Z Force 800 53/Trail EPS]

Those "Bosses" broke on quit a few and mostly because of a bad design. But others found the piston hit the valves during overlap because of a timing issue or stretched chain or a tensioner issue, that momentary pressure transferring to the cam would break the rocker mounts/bosses. So look at the piston for marks from valve contact. I thought they fixed that design flaw and pulled all the bad heads...guess not.