Small Engines (Lawn Mowers, etc.): sticking intake vavle, valve stems, valve job

Question
I have a B&S 11hp, 252707-0621 mounted in a riding mower.  The intake valve hangs up and it loses compression.  I took off the head and accessed the valve springs and added some lubricant to free it up and it became loose and cycled normally. I reassembled the engine and cut the lawn without a hitch.  I then shut it off and let it cool down. 2 Hours later I went to try it and the valve had hung up again.  Short of a rebuild, can you offer any suggestions?  Can I replace the valves without the seats?  I appreciate you help. Thanks! David

Answer
You can replace the valves without replaceing the valve seats.  In fact, very few mechanics or machine shops will even replace the valve seats...doesn't seem to work to well.

The valve stems are 5/16 inch, at least that what Briggs calls them.  Briggs sells special reamers to clean the valve guide, and for a top quality valve job Briggs sells tools to replace the valve guide.  

If the vavle is hanging, you can probably just remove it and clean it with a wirebrush, re-install to check the clearance and lap with rough and then fine compound.  

If you pull the carb and head off, basically have it all ready to do a valve job, you local Briggs dealer can do the rest since they have all the special tools.  By doing most of the labor yourself you will save a lot of money.  With clear access to the valves, a shop should not charge you more than 1 hour labor to install a new valve, valve guide and set the clearance.  I'm guessing to buy all the tools you would pay about as much as a shop would charge if you pull all the misc parts so they can access the valves.

Eric