Sounds to me like it's leaning out !!! Sucking all the gas out of the float bowl.
Happens quicker on a hill cuz its using fuel faster to climb.
That's why they keep telling you to check the floats. To ensure the bowls are at the
proper level before you start to climb.
I had that shit happen to me before on Olds. hill at Glamis. I had Just bought the
bike, didn't know shit about it. The engine ran hard up the first 2/3 of the hill and
then fell off and almost completely stalled out. I would turn it around and in a second
or two the throttle response would come back. I thought (my world was ending) there
was something majorly wrong with the engine. So....we headed back to camp.
I found that I was letting the fuel level get too low in the tank. On the incline there
wasn't enough fuel at the petcock.
I ran out of gas about 3/4 mile from the hill, the fuel pickups (in the tank) had been
removed and I had no reserve. Been back with full tank, no problems.
It just sounds like your float bowls are emptying out on you. Check your pickup screens
inside the tank (remove the petcock). Make sure the fuel lines aren't blocked or kinked
or really close to a pipe or something else really hot. Check the FUEL FILTER. It may be
clogged too.
In the other post about checking the plugs the guy wasn't talking about doing a plug chop.
Just pull the plugs and look to see if they are overly black. They will probably look pretty normal
when you pull em though...IMO.
Reread the plug chop threads another time or two, they will probably make more sense. You
have to do it with brand new plugs and it will tell you if your mixture is off.