Motorcycle Repair: runs rich from idle to 1/2 throttle, reed valves, pilot jet

Question
I have a 1993 yz250 that ran well under all conditions.The bike was not run for a couple of years & when i tried to ride again it was running rough unless i ran it at more wide open.It was also smoking excessively.I was advised that the crank seal in the trans may be leaking & sucking oil into the crankcase.I replaced the seal.This seemed to help but when riding it still had poor low throttle response & crapped out unless opening the throttle more.I have tried dropping main jet sizes to 2 steps smaller & lowering & raising needle.I dropped pilot jet sizes 2 steps.
I also cleaned reed valves & reversed them to get better sealing.I changed needle & seat in carb & set float level.If i shut fuel off & run it starts to run better as fuel in carb gets low & will idle & have good response until it starts to run really lean before it runs out of gas.If i run it with the boot off air cleaner side of carb it looks like a lot of fuel is coming out of main jet port even at low throttle openings.If you have any suggestions it will be appreciated.It doesn't make sense to me that this bike ran well at all different conditions before & now is running rich.
                      thanks Ron
                 e:mail ronpm2@aol.com

Answer
Hi Ron,

First impression is the fuel service level is too high (rich).

Thoroughly clean all circuits of the carbuertor.

When tuning the carb, make one change at a time to know the effects the change has on performance. Multiple changes may yeild positive results if lucky, though often is fruitless and a waste of time.

Read the spark plug.

Check compression and pressure test the engine to verify the integrity of the seals and combustion chamber.

I sent tech information files to your email. You may reply to my email.

Respectfully,
Mark Shively