$1000
You can get a rear sprocket wheel with fewer teeth. You can also install a set of bigger carburetor jet needles instead of the original one. The original jet set is called 100, but you can buy oversized jets of the sizes 102 and 105. Finally, it is possible to install the XR100 carburetor on the XR80 but it takes some work.
I don't know, but I would post the question on thumpertalk.com. You will get alot of help there.
No only 2-stoke bikes have powerbands, the xr100 is a four stroke.
My opinion and my knowledge the xr100 is slower than the xr80 because I had both of those bikes and the xr80 always beat the xr100
The Honda xr100 has 5 forward gears 1-down, 4 up.
a dirt bike
there is a screw on the carb. be sure to adjust while the engine is running so you can tell by the idle when it is set properly.
Usually the best jet sizes for a Holley carb are the ones that came in it from the factory. Sometimes you can improve performance slightly by stepping up or down one or two jet sizes.
the main jet sizes vary because there a few of them but i hope this link will help
They're not.
The xr100 uses straight unleaded gasoline. (car gas)