Unbolt the valve/head cover and remove it. Remove the right side clutch cover and remove the centrifugal clutch, the change clutch, and the oil pump. Unbolt and remove the timing chain tensioner. Unbolt the cam gear and lower it just a little until you can get the timing chain off it and let the timing chain fall down through the cylinder and remove it from the primary gear on the end of the crankshaft.
To install, take the two plugs out of the left side cover and turn the crankshaft until the "T" mark lines up with the mark on the over. Now drop the end of the chain down through the side of the cylinder and put it on the primary gear on the crankshaft. Make sure both lobes on the camshaft are facing down and put the chain on the cam gear with the punch mark on the gear straight up and the two lines parallel with the top of the head and bolt the cam gear back to the cam. It's a good idea to use some blue locktite on these bolts so they don't try to back out. Now, look at the "T" mark on the other side and make sure it didn't move. If it did, line it back up and make sure the punch mark on the cam gear is still straight up and the two lines are parallel with the top of the head. If you have trouble, keep repeating until you get it right.
When you get all the lines lined up right and the cam gear bolted on right, it's time to put the tensioner back in. Unbolt the bolt in the end of the tensioner and take a small flat screw driver and stick in the end of the tensioner and turn it clockwise to retract the tensioner arm. Hold it in this position until you get the tensioner bolted back up. Then, release the screwdriver and the arm will automatically extend and tension the chain correctly.
Now just reinstall the oil pump and both clutches and put the side cover back on and then put the valve/head cover back on. Don't forget to put the two plugs back in the left side cover.
If you don't understand something or need more help, let me know and I will try to explain it.