I have a near thirty year old John Deere 112L mower. It comes with this FB460V although the engine on it now came from a Gravley Walk behind mower.

It's always been slow to start when cold or even cool, with both engines for that matter. In the past couple months it gotten to where it floods very easily. Now once I get it started, it starts and runs great, under load all day. It runs a bit rich under no load condition.

With the breather off, I see rapid pooling of fuel in the air intake and carb. I still have to use the choke to start it, but I may have to dry the plug a couple times and use jumper cables to maintain enough starter speed to make it go.

Once started, it is clearly rich, but after a few seconds clears somewhat. The idle mixture screw has little to no effect on idle or part throttle. At full throttle it still flutters some, until I engage the PTO. Under load, this thing runs like a champ. It'll cut thick 8" tall fescue at near full forward speed, even with the bagger attached.

I have removed and disassembled, cleaned and inspected the carb and have found nothing so far. All passages and orifices seem to be open, and all throttle, governor and choke adjustments have been set and triple checked.

The float isn't soaked, it's plastic, not cracked and doesn't slosh.
The needle and seat seem in fine condition, is adjusted and it is shutting off flow.
The Idle mixture is not scared, scratched, bent or otherwise marked and the seat seems to be fine.
Main, jet, main nozzle and bleed jet all seem fine.
All "O" rings, (the few there are) are not nicked, cut hard or brittle.
Gaskets are also in good condition.

What am I missing? Anyone got any magic?

Thanks for all the help guys :thumbsup:

Check your valve lash, it's possible the intake valve may not be seating well and you may not have enough clearance either.

Thanks 30yearTech. That may well explain the bit of compression I'm getting back through the carb during cranking, but I dismissed it because of the very good performance under load. I'd thought any valve seating issues would reduce horsepower significantly. I'll look in to it.

Well, valve lash is fine and compression is strong. I didn't measure it, but it pops the old thumb off with authority.

I have to use a heat shrink gun to warm the head in order to start it. Odd thing is that it can sit for several hours, cool down completely and will start without much delay.

Go figure! I decided to check the coil adn coil air gap,..it's fine. This thing is makin me nutz!

You may have to remove the head and inspect the valve seat and face to see if its seating all the way around. I just had one that had clearance but was only seating around half of the valve seat (intake) it was getting a lot of blow back into the carburetor.

Correcto! Pulled the head today. Badly recessed valve face. One side wasn't seating at all. Off to the machine shop, reface, trim the stem length, now she fires right up and purrs like cozy kitten.

You'll laugh but for the last two months, I've been heating the cylinder through the spark plug hole with a heat shrink gun AND taking the air cleaner cover off before it would start. LOL!

I thought it was running pretty strong once started, but there is sooooo much difference now.

Thanks 30yearTech!