[Jeepwm69]

I know Shadetree has reported that some of the 350 Rancher heads were defective and had a tendency to drop the valve seat.....

This one for sale on ebay says "valve seat dropped" I can't really tell from the pictures exactly what has happened.

2004 4X4 HONDA RANCHER 350 CYLINDER HEAD VALVES WITH CAM CAP | eBay

What exactly happens when a "valve seat drops"?

I know what the seat is, but I guess I don't see how it can "drop"

Anyone have a better pic of exactly what happens?

 

[SamUK]

I'm assuming it's when the seat isn't seated properly and exhaust gasses pass around the seat when the valve is closed as well as the valve not being able to close properly.
I'd have thought they drop when the alloy head expands, sounds like a manufacturer fault, poor machine work by the factory.

 

[shadetree]

I know Shadetree has reported that some of the 350 Rancher heads were defective and had a tendency to drop the valve seat.....

This one for sale on ebay says "valve seat dropped" I can't really tell from the pictures exactly what has happened.

2004 4X4 HONDA RANCHER 350 CYLINDER HEAD VALVES WITH CAM CAP | eBay

What exactly happens when a "valve seat drops"?

I know what the seat is, but I guess I don't see how it can "drop"

Anyone have a better pic of exactly what happens?

the early trx350 ranchers had a defective valve seat. nothing to do with dropping a valve. when the head heats up, the valve seat works its way out of the head, when this takes place, the valve seat sits there slapping the crap out of it between the bottom of the valve and the valve seats top edge, herby beating it to death, ruining the valve angle face and valve seat face. this makes them sound like a loose cam chain when you rev the motor.

 

[shadetree]

I know Shadetree has reported that some of the 350 Rancher heads were defective and had a tendency to drop the valve seat.....

This one for sale on ebay says "valve seat dropped" I can't really tell from the pictures exactly what has happened.

2004 4X4 HONDA RANCHER 350 CYLINDER HEAD VALVES WITH CAM CAP | eBay

What exactly happens when a "valve seat drops"?

I know what the seat is, but I guess I don't see how it can "drop"

Anyone have a better pic of exactly what happens?

and to touch base when a valve drops ?, these happens when the keepers let go of the valve stem, or the valve stem breaks ?, then the valve drops down smacking the piston, this is what dropping a valve means.

 

[Jeepwm69]

Good info.

So on these loose valve seat 350's, seems like I remember you saying you had one that wasn't readily visible, and would only rattle when it got hot....

Is that right? I just picked up an 05, but no cylinder or head with it. I have a 2000 head from my neighbors parts bike. What am I looking for as far as tell tale marks that the valve seat is loose?

 

[shadetree]

Good info.

So on these loose valve seat 350's, seems like I remember you saying you had one that wasn't readily visible, and would only rattle when it got hot....

Is that right? I just picked up an 05, but no cylinder or head with it. I have a 2000 head from my neighbors parts bike. What am I looking for as far as tell tale marks that the valve seat is loose?

you can't see the bad valve seat. it only works its way out when the head gets warmed up, once you shut it down, the valve spring forces the seat back down into the head. then you crank it up, and the process starts all over. I had an '04 trx350 rancher project awhile back, it would do just what I am saying. I replaced every damn part known to cause this noise ?, come find out, after I spoke with my bud at Honda, he's like '' oh yeah...I forgot to tell you..those trx350 ranchers had a defective head/valve seat on some of them '' !. great..lol.

 

[SamUK]

My thinking on this wasn't far off right then. I'm learning slowly shady lol.