Hello my name is Kenny
You say that you checked compression, can you give me that number ?
I Guarantee that you have a compression issue, you need to check that, I have NEVER seen where water and mud into a engine will survive, take the spark plug (so you get the right size gauge) and you can go to a Autozone or any of those chain Autoparts store's and you can rent one from them or if you have a Harbor Freight Tools, you can pick one up there for about $10
100 psi (which is what this unit will require to start) will blow your thumb off, but 80 psi it will not start, 20 psi with the thumb, you'll never be able to tell the difference.
I have seen this a lot on this model, they are very sensitive to low compression.
Let me know what you come up with, I have a manual on that if you need anything out of that.
I'm sure you did something to the piston and rings, depending on how long he rode the unit will dictate what happened to the cylinder.
This unit is really easy to work on, you can at least pull the exhaust pipe off and look through the exhaust port and or just pull the head off, but if you can I would try to do a compression test, its always better to have an idea before you go into it.
If you need help with getting anything apart then let me know, you might be able to get away with replacing the piston and rings, these little bikes are more forgiving.
I checked the compression and it is low 62 psi, my next move is to remove the exhaust, head, and remove the cylinder. From there I'll assess the damage. Thanks
I do have one other question, I am getting the gas filling the cylinder, I have replaced the needle and seat in the float bowl and still have this problem.
That is likely from maybe the low compression, remove the carb and put it in a vise, then hook an external fuel tank to the carb, see if it leaks, if you have to pull the float bowl off and then hold the float closed, and see if you have leaks somewhere else in the carb, you float level could be a little high, also make sure the "float" floats, drop it in some water just to make sure.
Well i think you found your problem, good lesson learned here, the old thump works sometimes but it can bite you also,
Glad you got it figured out, let me know if you need anything else.
Thanks again !