You may have a loose clutch cable.
You slowly let the clutch out while throttling up a little bit, when the bike starts to move give her a little more, let the clutch out and take off.
quads and motorcycle use a wet clutch system so there isn't a separate oil for it penis , just uses the engines oil. Make sure your using a compatible motorcycle oil too
a motorcycle grade (moly free for the clutch) 20w-50 JASO rated oil would be great dont use car oil. you could ruin your clutch
Removing and replacing the clutch on any motorcycle is an involved job. Your best bet is to purchase a book like the Haynes manual which will take you through removing the clutch basket and replacing the clutch plates. It will also instruct you on the correct set up and oil for the clutch. Correct set up of your clutch could save your life on any bike, so its best not to take chances by guessing.
remove the bolts holding it to the water pump pulley, then wiggle the fan out under neath the radiator hose ( or take it off if you like) there will be 4 bolts on the front of the fan holding on the fan clutch. good luck!
I would start by checking the clutch reservoir level. If it is OK then try flushing the whole clutch hyd. system if that does not fix it. Your clutch might be the problem.
Take it to an authorized Yamaha mechanic. This is a tricky proceedure that should not be undertaken by a backyard do-it-yourselfer.
Pull start it in a mid range gear. While pushing down on the clutch pedal stab the brakes. It may take a while so make sure you have room to drive. If that does not work you will have to split the tractor at the clutch housing.
You can take the motorycycle test even if you don't have motorcycle yet.
To remove the clutch fan on a 1993 Mercury grand marquis hold the fan in place using a clutch fan tool, then remove the holding nut. Most large auto parts chains will loan you the tool.
adjust the clutch
Some vans don't hav a fan clutch but electric fans. If yours does have one, simply remove the 4 bolts holding the fan on then take the bolts out of the clutch. If it has just one big nut a special tool is required.