Motorcycle Repair: sprockets, air gauge, bicycle tire

Question
QUESTION: can you please tell me how to go about changing the sprocket on my engine. i have a 1990 KX 500
ANSWER: Hi daymen
         You have to first find the master link in the chain,it is the link with the clip.Remove the chain,put in motor in 1st gear,grap a wrench to fit the nut.Remove the nut,washer and gear.when all that is done assemble in the reverse order locking the nut to atleast 45 lbs of torque.glad i could help.

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QUESTION: 2 other questions please. my bike(1990Kx500) was setting for about three years and i noticed my forks sagging a little. what can i do to fix it or should that be done at a shop? Also, if my exhaust is very loud, do i need a new muffler or can i repair the one i have on there? My last one please. If i change my pipe and muffler, will i have to have my carburator rejetted and what are some of the  things i need to do when putting on new pipe and muffler? Thanks A Million

Answer
You forks i believe on that bike have a air valve on the top.Take a air gauge and see how much pressure is in them,and then take a bicycle tire hand pump and put a couple of pounds in each one of them.as for your pipe being loud, you can buy packing for your silencer from a dealer.look and see if there is either bolts in the front of the silencer to pull it apart,if not you have to drill out the rivets in the rear pull out the core of the silencer and repack it.To do that first get the packing,it will be in sheets cut to the width that you will need wrap it around the core(perferated pipe)tightly.you can secure it tightly with either tape or zip ties,if the dealer tells you to secure it with wire dont because it has to be able to burn off so that the packing can expand to fill up the silencer.Glad i could help!