"Looking at the carb diagram, the solenoid inlet needle goes into the inlet seat.
When the key is turned on the solenoid engages and pulls the solenoid needle away from the seat. "

I'm not sure how you came up with that?
The fuel solenoid is simply a plunger that blocks the main jet when power is removed to avoid after fire/run on.

The float needle & seat simply isn't sealing off the fuel flow for whatever reason. Possibly a piece of crud??

Bill,
Thanks for the reply, I now undestand it better.
With the key OFF the solenoid plunger is in the extended position that SHOULD seal off the main jet. With key turned ON it retracts and lets the fuel flow.

Although I'm still stumped with the float. By blowing into the fuel inlet valve hose with the float at rest no fuel can enter, by pulling down on the float a bit the blown air will now reach the bowl, however, that distance of float travel is minimal. Without touching the float no air can be blown into the bowl, quite the opposite of what I expected since it's flooding.

I really need to get the carb off to disassemble and clean, but I'm still unsure how to adjust the float since it has such minimal travel distance.

Since the carb hold down bolt heads are stripped, I'll try to put two nuts on the stud, locking them together and attempt to back out the studs that way, but I'm not optimistic about that since the studs are brass and are soft.

Floats generally don't go out of adjustment. Metal floats can spring a leak and fill with gas but I've only seen that rarely

Bill is right on point advising you to look for a piece of crud. A very small piece of dirt can result in exactly what you're experiencing.

Also look for a loose jet or nozzle.

Be VERY careful with those carb studs. Snap them and you'll increase the difficulty factor of this repair exponentially.

The float is plastic so quite unlikely it has a leak.

I agree, removing the studs will be a challenge since they're brass. Will soak with penetrating oil and let it sit before attempting removal. Can't use heat that can potentially start a fire.

Once the carb is out I can get a better idea of what the problem may be. I still don't know if the float can even be adjusted if need be since I don't see any tangs to bend.
There is just a pin that holds it in place.

@mownie
Thank you for taking the time for a comprehensive explanation on how the carb system works. I now see the reasoning for the solenoid.

I agree, I think it's best to replace the carb and studs to have it function properly. Since the rider is so old and not in the best of condition my neighbor will have to decide if it's worth the cost of the replacement parts.
He checked a local mower parts store and was told the carb alone is 150.00. The mower is not worth investing that much into since the mounting studs will be another 12.00

I checked on Ebay and found a new replacement carb for 90.00 and free shipping. The only problem is the part # is different.

http://www.ebay.com/itm/331223330404?_trksid=p2060778.m1438.l2649&ssPageName=STRK%3AMEBIDX%3AIT#ht_2894wt_1242

The parts for his 28N707-0131-01 indicates Carb part # 497061.

The replacement part on Ebay indicates replaces Carb Part # 498061.

Looking at both parts schematics I see all the component carb parts are the same, the only difference is the carb part #. I think it would fit and that the 498061 is newer than the 497061. I can't find a 497061 replacement doing a google search.

I'm going to call the seller and see if he knows if the 498061 will work.

Many thanks to all that responded, I sincerely appreciate your input.

Instead of penetrating oil get a can of PB Blaster which is sold almost everywhere. Judicious application over a few days works amazingly well especially on non like metals.

You have to get the carb off to repair or replace so that's first.

If you don't have the knowledge to see what the problem is with the carb I'd get the carb to someone who does before I spent the $$$ for a new one. Physical damage aside I've never had to replace a carb that I could get parts for and that's a lot less expensive than a new one... and that's IF you can get the correct replacement carb.

This post was edited by justalurker on Mon, Jun 9, 14 at 19:28

Follow Up,
I got the studs off by using PB Blaster and vice grips, came out quite easily. I then used a file and squared off the rounded bolts to fit a wrench. Next I used a die to thread the bolts the vice grips had damaged. Keeping these only as spares since we bought brand new ones as a replacement.

Next I ordered a new carb on Ebay (big mistake).
While waiting for the car to arrive I took the original carb apart, cleaned everything and used my compressor to blow out all the orifices. I replaced the carb bowl rubber gasket with one from my spare parts.

When the new one arrived I installed it, I then opened the fuel shut off valve. Gas started pouring out of the top of the bowl and flooded the engine. While it was leaking I tried to tighten the solenoid to put more pressure on the bowl gasket but it did no good. Removed the carb, then the spark plug, and cranked the engine until all gas was discharged. Also changed the oil just in case it got contaminated with fuel.

Next I installed the old one (original) I rebuilt.
No fuel leaks, started right up and runs smoothly.
I returned the new one purchased on Ebay and got a full refund less return shipping. I couldn't believe a brand new carb would also have float issues. I tested it before installing by blowing through the fuel inlet while in the mounted position. I was able to blow air into the bowl (worked properly. I then turned the carb upside down and blew in again, no air entered since the float was in the closed position (worked properly).

I have no idea why the thing overflowed like that and at this juncture no longer care.

Yeah, some folks can fall off a 12 foot high wall onto concrete--and never get hurt!
Consider yerself lucky! And, lucky because yer fix worked! by: That old sage--rusty Jones