I have ordered the replacement parts to replace the composite geared camshaft on Non-John Deere FD620D BS03. I ordered the $290 kit to do the repair from an ebay retailer as well as new water pump for $56.
I pulled one cylinder head and manifold then the crankcase cover in the last couple of days. I did find two finger tight nuts holding down the carb.
Removing the valves can be done with your bare hands. No need for a spring compressor. Valve diameter is within specification and the seats look OK just need lapping the old fashioned way -- by hand. The valves need to be cleaned up with brass wheel to get rid of the carbon. I will install new springs and push rods since they came with the kit. See below pictures of the head and valves.
I also removed the back cover and cover inside of the engine looks good. I will probably pull the pistons and provided the bore is fine I will simply deglaze and put in a new set of standard size rings. See pictures of the back cover (front and back side) plus the inside of the engine. below. Overall, I am please the condition of the motor is pretty good. There is residue of oil that looks like is leaked past the rear crank sea. It is 20 years old and has 760 hours of use. Pulling the back cover was problematic because I failed to find anything about how the engine is mounted via the bottom of the crankcase cover. When I removed the 8 cover bolts and oil drain on the side the darn cover would not budge. I felt under the mower and there were two bolts. Removed them and the cover came right off.
Manifold has to be removed (4 bolts).
LEFT SIDE HEAD -- Valves removed and combustion chamber wiped clean with CRC Lectra motive parts cleaner. Left head stem diameter measured . Both valves are .001" greater that minimum stem diameter. .234" min. diameter on INTAKE. .233" min diameter on intake valve.
Still need to be cleaned with brass wire wheel on the bench grinder while chucked in electric drill with the valve stem taped to prevent marking. See below for the work in process.
Below are some pictures of the crankcase cover and the inside of the engine.
Below is the root cause of needing a teardown and partial rebuild. The composite geared camshaft that fails between 700 and 1000 hours.
Crankcase cover with 8 bolts and two motor mount on the bottom.
Inside of cover looks pretty good:
Governor gear should be white. It has yellowed with age. It's being replaced.
Inside the engine looks pretty good:
Repair parts are due late next week. I will be able to clean and lap the valves before the parts arrive. I will pull pistons and measure the bore. The oil pump needs to be checked for any excessive wear and the screen cleaned out in the pump. Manual image is not identical to my model but it is representative of the oil pump.