help, wont start

[hondamxerd]

i have a problem, my cousins 400ex will not start. i have checked all i know to check. including the following, nice big blue spark from spark plug, getting proper fuel, changed ignition modules, no metal in oil, clean oil, good gas, good compression, exhaust free flowing, electrical wires, charged battery, clean a/f, and checked for anything abnormal looking. i am completly stumped.
i have always done my own work on my quads, but never had any problem like this. it started with a loss of power accelerating in 3rd gear, slowly decreasing in rpm, pulled clutch in stopped, heard loud clicking sound.

[starky]

possibly a bent valve, your intake valve could be stuck shut...

[hondamxerd]

thought of this, took valve caps off and cranked engine, both valves are moving properly

[starky]

the vavle could still be bent though, it could be staying open to long or vise versa. Only a leak down test will tell/

[400ex28]

Originally posted by starky
the vavle could still be bent though, it could be staying open to long or vise versa. Only a leak down test will tell/

true...

[Quad Dude]

that could be the problem but he said it had good compression ane with bad valves wouldnt the compresson not be there