Ok, Im new here, would like to thank anybody that may be able to help me figure out the problem I am having. I recently purchased an 86 lt250r as a project. Would like to get her running before going into the cosmetics etc.  The guy I bought it from said it had sat about three years but supposedly ran before it sat. I get it home, clean the carb, and flush the tank. new gas and mixture, new spark plug. cleaned air filter. Had great spark. Put everything back together hoping to get her going and she wouldn't fire at all. I finally got it to pop on a shot of ether, and it would stay running for all of three seconds then foul the plug with black oil. So, I figured it must be right side crank seal. Replaced left and right side crank seals, tore down the top end while I was at it, replaced reeds with brand new boyesen power reeds, all new top end gaskets etc. Put everything together and now it wont even hit off of ether. I am no longer sucking oil from the tranny which is good, but can not for the life of me figure out what is going on with this bike. Timing marks on stator are lined up, .010" clearance between pickup and flywheel, good flywheel key. Brand new stator. swapped coil with another zuki quad and she has good hot blue spark. any ideas as to what I could check next? I have even tried fuel straight into the cylinder and nothing. 150 psi compression. Any help would be greatly appreciated. thank you.

if it's fouling plugs, sounds like a jetting issue.  what spark plug are you using?  what gas and oil?  what ratio are you mixing it at?

Also, dont hit a 2stroke with ether, good way to damage the motor.

check your jets, maybe a plugged jet, i know you said you cleaned the carb but never know. make sure the jets are clear as well as the other ports in the carb.

just sounds like it's pig rich on the jetting.  What are your jets?  carb?  needles position?  elevation?  air box lid off?  air filter?  Pipe?  any port work?