Rancher 420 4x4 2021 valves not opening and closing

[DeadBattery 6]

A little backstory from what i know, my buddy had his top end rebuilt, he broke it in, few rides later his coolant hose comes off, he lets his cool down, and he starts trying to go home, in the end blowing it up, there was scarring on the cylinder wall, metal chunks, piece of the piston broke, the valve has like some build up on it, and they look old. I'm rebuilding my buddies honda foreman 420 4x4 and after battling with the wrist pin on the piston, I put it back together, everything right, I turn it over, and it didn't start, I sprayed starter fluid in the cylinder, it backfired out of the airbox, and the reason I'm guessing is the valve is ceased, I'm not sure if it's the rod that's coming off or if the valve is ceased, when I turn it over I hold the rocker arm and it doesn't move up or down, but I don't know how to check if it's the rods falling out. Is there a way I can check if the valves are ceased or the rods are coming off.

[jeepwm69 7,232]

On 8/12/2023 at 1:29 PM, DeadBattery said:

A little backstory from what i know, my buddy had his top end rebuilt, he broke it in, few rides later his coolant hose comes off, he lets his cool down, and he starts trying to go home, in the end blowing it up, there was scarring on the cylinder wall, metal chunks, piece of the piston broke, the valve has like some build up on it, and they look old. I'm rebuilding my buddies honda foreman 420 4x4 and after battling with the wrist pin on the piston, I put it back together, everything right, I turn it over, and it didn't start, I sprayed starter fluid in the cylinder, it backfired out of the airbox, and the reason I'm guessing is the valve is ceased, I'm not sure if it's the rod that's coming off or if the valve is ceased, when I turn it over I hold the rocker arm and it doesn't move up or down, but I don't know how to check if it's the rods falling out. Is there a way I can check if the valves are ceased or the rods are coming off.

 

Chances are the crank is shot if you had to fight the wrist pin.  The small end of the rods on the 420's almost always are ruined, requiring a crank rebuild.

 

What do you mean by "ceased"?  Seized? 

 

You'll have to pull the head off, turn it over to see if the push rods are moving up and down with the cam.  Cam lobes could be wiped out, could be a bad push rod, could be something up in the valve cover/rockers as well.

[DeadBattery 6]

Turns out the valves just needed to be wire brushed, ran fine after and he traded it.