Is there a good source to read about rejetting?  What is does exactly, specs, etc...

All kinds of sources on the internet.  When I was learning, which never really fully happened, I used the write-up oin factorypro.com.

Biggest thing is you need to figure out whether your bike needs more fuel or less fuel, where it's needed and then change something.  As the guys at factory pro tell you, if you don't know what it needs but you know it needs something, then just change something and see what the results are.  You can always go back to how it was before.

You can look at this site for starters...

http://pantablo500.tripod.com/

Also check the FAQ section here and search this site.

Anytime you rejet, you are changing the mixture.  Depending on which jets you change you effect a different area of the RPM band.

You should also know that early bikes have 2 sets of jets while the later models have three.  I believe the change year is 2001 but that might be wrong.

I posted a Dyno run of a stock 1993 bike that shows the mixture of that bike.

My feeling is that stock bikes have a lean idle which causes the bikes to be cold natured.

Others may disagree. The search function should reveal a wealth of information and conjecture.

after 40 years of working on car and bike carbs, all I can say is, don't screw with it if it ain't broke. The factory settup is far more precise than anybody in this list can duplicate. My stock '01 runs great. It stumbles just a bit for the first block or two, as it warms up, then runs perfectly and gets 75 mpg. The reason these bikes (and all engines with carbs) have chokes is because it is necessary to richen the mixture until the bike warms up enough to run without it.

My old GS 400 ran for 27 years with stock jetting. Carbs have a function that attempts to match the load and throttle position as best it can. When you change any part of the equation, you get changes to the whole deal. Best leave it alone. Unless you like tinkering around needlessly..