Just got the Z400 back together with new clutch, water pump rebuild, valve clearnce check and some major cleaning. Started right up and runs good exept it sounds awful! I still hear a metal wearing noise from inside the engine. Same sound I hear on the last day of our dune trip. I'm thinking the cylinder and piston might need to be replaced. Maybe even the rod bearings are worn? I guess the only way to find out is to a full tear down of the motor which I don't really want to do. Last time I rode it the power was there and everything ran great except for the clogged radiator that was causing it to over heat. What should I do? Should I just keep running it until something happens or tear it apart?

 

You can do a compression check, that will make sure your pistons and rings are good, as far as a crank or rod bearing the motor will probably have to come apart for that, Most quad motors i've come across are noisy *** motors and its really hard to tell what sound is suppossed to be there and which isnt, I personally would run it, but thats just me