Motorcycle Repair: dry spark plugs honda xl250r 83, cylinder head gasket, honda xl250r

Question
Hi Wayne,
My bike died the other day while I was riding it.  I was driving along at 65 mph and it dropped down to 55 mph with the throttle in the same position.  Then it started to drop some more and finally completely died when I got to the side of the road.  I have done some trouble shooting, and this is where I'm at:

Gas flows into and through the carb into the engine block, but does not make it to the spark plug.  There is compression.  When I turn the engine over with the kick starter and holding my thumb over the hole for the spark plug, it pops my finger off.  I also checked the spark, and there is spark.  However, after trying to kick start the bike for a while the spark plug remains dry.  

BTW, the cylinder head gasket is leaking, which I guess is a common problem for '83 xl250's, but my mechanic said it was no big deal if I didn't mind putting up with oil leaking onto the engine block.  

Any ideas as to what is going on and how I should reslove the problem?

Thanks!

Answer
Jeff,
try some carb spray or wd40 in the intake
and see if it fires on it. Then you
know it's likely a fuel problem.
If fuel is getting to the carb, it may
be a stuck float needle/valve not letting
the float bowl fill up.
You may need to remove the carb and check
the float needle/valve and the main jet
in the center and the emulsion jet under
the main jet.
Also check around the carb intake for any
air leaks. Check for vacuum in the gas tank,
could be a plugged tank or gas cap vent.
I will let you know if I think of anything
else.