Thumb throttle is really stiff, makes my raptor feel like butter. Any ideas on how to make it easier on the kids? The manual is only 4 pages long and doesn't cover anything.

Take the spring out of the carb. squeeze the spring between your fingers. If it feels soft then there is a cable obstruction. If the spring has alot of tension you can grind the diameter of the spring to make the wire diameter smaller thus reducing the amount of tension of the spring. Remember you can remove material, but you cannot add any so take your time with the grinding. hope that helps.

You can also cut a few coils off and stretch the spring back to the original length. I did this to my banshee when I went to the bigger carbs. It helps but you have to lengthen the spring out or it might not return the slide i.e. stuck throttle.....

The one my son had used two spring in the throttle housing. I tried it with one & it helped some. No matter what I tried it was always pretty stiff. Kids get pretty strong riding the darn thing.
Make sure that if you ride any hard pack or get in situations where you'll lift one rear whell going downhill that you lock up the diff. If you don't the brakes in the rear won't work. Since the brake disc in on the axle hub the wheel that's in the air whill just freewheel, and there will be no braking from the rear. My son almost had a hairy crash because of this fact, luckily he's sharp and didn't spas, just went with it and bombed down this gnarly downhill section with ruts. Scared the shiznet out of me!!
We just pulled the diff apart and welded a bead in the side gear valleys, so that the other gears couldn't rotate through, basically a poor mans spool. The earlier years had a kit you could use to lock up the diff. but I think after 01 they didn't offer it anymore.
Try talking to John Zernikow (Iknow i didn't get it right but you get the idea) @ temple City motorsports he's done all kinds of stuff to those bikes, good guy too.

Thanks for the info everyone