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YZ250 fowling plugs/ not idling. I am out of ideas!

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Here is the deal I am out of ideas, so I came here to see if if there is anything I am missing before I start mass tear down.

Problem: out of the blue, nothing has changed my YZ has started fowling plugs at an insane rate. I fowled one yesterday playing in the pasture and 2 today in the parking area headed to the trail. I have not changed anything on the bike and it usually runs perfect. It will not idle at all, if you let go of the throttle it goes straight to dead. I also have an increased amount of smoke from the exhaust at idle and under power.

Machine Specs:

1996 YZ250

recent top end (20 trails hours maybe) has great compression

PC pipe and silencer

Carbon fiber reeds

175 main

42 pilot

NGK BR8ES plug

32:1 ratio

Things I have tried:

new plug ( stock and one heat range warmer)

Complete tear down and cleaning of carb (btw carb cleaner burns like a :smirk: when you get it in your eye.)

cleaned the air filter

reeds look good

adjusted mixture screw

attempted to adjust idle speed, but has no effect.

I am open to suggestions, do I need to look toward case seals? Could a tank of bad gas cause all of this? Anything helps and I will post this in the Yamaha 2 stroke forum as well. I know many people dont venture here often and thank in advance.:smirk::worthy:

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Ruling out bad gas is easy, so dump what you have for a fresh batch from a different gas station.

Any notice of change in compression?

What are you running for tranny oil and have you seen an change in level?

Make sure there are no obstructions in the exhaust system. I once had a piece of built up carbon from inside the pipe break loose and obstruct the stinger end of the pipe and experienced a problem like you're having.

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