Welcome to the forums.  I would first make sure that no previous mods to the carb were done. ie...do you have stock jets now, did the p.o. shim the needle? Is the brass mixture screw still in tact? Once you know these you will have a better idea of where to start?

Also, is it a stock air filter?

Exactly right... can't advise where to go until we know where you're at.

It is a stock air filter. It is a 1997 with 2457 miles on it.

Check bolts on header flange, & do it when its cold & dont take your Caveman with you,, 1/4' ratchet, feeel of it,, go Eeeeeasy,, you can tighten it again,
Check where muff meets header, too, a candle is your friend.

It looks like they took out the brass plug already.there is a brass screw with a flat head on it. Now i am wondering what else they have tried on it already.

Be sure that the engine is at operating temp before adjusting the carb.  A 5 minute ride is the quickest way to get it to that temp.
Letting it idle for a few minutes is not adequate; idling for 10  minutes would do it though.  You want it well beyond the point where it no longer needs the choke.

rodeoclown wrote on 03/07/12 at 04:56:49:


Some backfiring is normal, so you may not have any problem there.

Is it running bad now ?,....you never did say. If not, why are you just itching to hack the carb,.......probably for no reason ? Do a plug read, and go from there. You said the idling improved when you adjusted the air/fuel mixture,....thats good.
You better have a dial calipers when you start playing w/ the white spacer. It is a critical adjustment,....and also one that may not be needed.......unless you have a lean spot in the low to intermedieate throttle range.