20 Most Recent 2006 Yamaha WR 250 F Questions & Answers

I would remove the carb and give it a thorough cleaning. If you have that junk in the bowl, chances are the jets are clogged with it too.

Some videos here https://www.google.com/search?q=2007+wr250f+getting+no+spark ..

check your crank bearing could be sucking air

Sounds like the crankshaft has come out of phase. If the crank is out of true, damage to rod and crank bearings can occur.

open rear brake resover cap ,drain some fluid out,remove brake pads,clean piston,push piston back into caliper,refit pads,pump up rear brake

Drain tank and carb float. Use Seafoam to dissolve any ethanol that made the gas go bad. Gas loses it volatility after about 6 months of storage. The ethanol will coat the carb and interfer with the proper operation. Check your battery and make sure you use a new spark plug set at the right gap.

Check ground wire, make a 12" jumper wire (remove plastic casing from both ends, touch wire to bulb socket and steel frame, if the light get brighter clean grond with sanpaper//emory cloth and bolt it back down. You may need to check each light. if all good and no bulbs get brighter when good grounding there is likely a loose or broken wire to or from the battery/relay switch.

okish? make sure they are OK.
possibly too rich, buy a new airfilter element, and adjust the air screw when it is hot, (turn out, anticlockwise half turn) if this doesnt help you should turn it back in the half turn.
you could also lower the needle by raising the clip one notch
take notes of what you do so you can change it back if it doesnt work