This would depend on what sprockets you are running and what chain you plan to run. If you don't have a local shop to ask, I would go to this website and ask them: http://www.1trail.com/sa/p/Driven_USA_Suzuki_DZR_400_00-_04_MX_Front_Sprocket.htm
52 dollars
You can earn Zeny by defeating monsters and selling the junk that they drop. You can hunt for monster cards or rare items and use a merchant to sell them. Merchants can earn more Zeny from selling items to NPCs.The exact amount that Merchants can save from purchases from NPCs is 24%. 24% is also the percent of extra money Merchants get from selling items to NPCs.If you want some suggestions for areas to grind to make lots of money, here's some suggestions:Low Levels: payon caves lvl 1 (opal sell for 3k, skull rings for 5k)Mid Levels: Hill Winds (can make ~500z per kill)High Levels: Rachel Sanctuary (can make ~400z - 700z per kill with the chance of getting rares easily worth over a mil each)For tips on how to get rich in ragnarok online, check out the Zeny Making guide at http://guiderz.com