Justin

The engine will rev to a certain RPM in each gear and then runs out of any additional power.  The revs will slowly climb past that point in 1st and 2nd.  As the forward speed increases and the mechanical advantage decreases, the engine can no longer pick up revs and my speed maxes out.

What is a "slider".  I just took the carb out and was inspecting it for rust or contamination.

Pretty clean inside.  Just a hint of red dust in the float bowl.

BUT the black thinggy that goes in from the top will not move with reasonable finger pressure.  Since there is a spring in the top pushing down on this, I suspect that this part is stuck.  Is this the "slider"?

Is there a fix?

Thanks for you help.

I think you've found the problem.  

This thread stared out with oil in the airbox, and now I see that the "slider" is really oily.

That oil, apparently, caused the "slider" to stick.  It was stuck hard enought that I had to pry it loose.  Once it broke free, though, it moved OK.

I cleaned the hole and the slider itself, and now it seems to move freely.  I'll put the hole deal back together and see if it runs OK.

Thanks so much for the help!

Ranger Bob.

Guys,
I had this problem, but not nearly as bad.
If you overfill the oil sump or lay the bike down, you will get oil in the airbox and carb. This will create problems.
My problem was the carb piston became stickey with oil and the bike would not go into warp speed. (accelerate at higher RPM for those in Rio Linda).
I had to remove the carb and clean the piston and its bore. This fixed the problem. This can also happen if you install a K&N air filter.
I'm now at 12 SuperTrapp discs and can accelerate to warp factor 3. My rear Metzler is going away fast.