79 WR250

I've got a 79 WR250 that won't fire up and I'm trying to diagnose. Original motoplat with large flywheel. Original crankshaft, carb and fresh top end. Bike will not fire at all. Not even a pop. Pulled exhaust thinking plugged P pipe etc-still no fire. Entire ignition gone over by VS and blessed off as giving great spark. Won't fire on bump start down hill. Swapped carb with known good carb still nothing. Ground wires run from stator to coil to cyl head. Will spark a plug laying on cyl fins but won't fire up. Mag timing set to 2mm. Timing pin location is at/near 4 o'clock location. Any help would be appreciated.

is the plug wet when installed, kicked, then removed? bike is likely flooded....especially after the pull start didnt work.

had this happen on a 78....ring cracked

yea you might have a crankcase plumb fulla gas might turn it wheels up with the the plug way far away NO SPARK!!! AND GIVE A FEW GOOD SPINS

A few more pertinent details, carb working fine I e cases not full of fuel, plug getting wet with fuel but in normal fashion i.e. Not flooded with fuel, great compression-new bore and Wiseco piston Assy. I did replace the cases due to case rot and I believe they were from a 78 motor. Can anyone confirm the location of the timing pin as about 4 o'clock for the large diameter motoplat flywheel used on the WR?