broken cam sproket?????

[toyotakid]

ok i finaly got the bike together after blowing 1st 2 times and about 4 months i started it up and let it warm up eavrything seemed fine. then i went for a about mile and a half ride down the road in 3rd pined i heard this clicking noise and i cut the engine. then after trying to get it running again (check spark, compression) but no fule so i rebuilt the carb and still wasnt getting fule so i took off the valve covers and turned over the motor and the valves wernt moveing so i took off the cam cover and saw i broke off the tooth that holds the sproket in place.

how did this happen was it that maby i forgot to tighten the cam sprocket or was it going wide open for 5min or something ealse?????

[PlanetMinis.com]