You don't need to remove the engine. A valve job can be done on the bike.
Get the shop manual. You can download it from one of the sticky threads.
Head removal summary:
1. Disconnect exhaust, carburetor, top engine mount/throttle cable hanger, and spark plug wire
2. Remove cam chain adjuster
3. Remove cam access door
4. Rotate engine to tdc and mark the cam chain at the top
5. Remove cam sprocket - you will need to access the crank bolt via the small access port in the side cover to hold the crank
6. Zip tie / bungie cord the cam chain so it stays taught
7. Remove the two Allen head cap screws from the cam side of the head
8. Remove the four head bolts
9. Remove the head
1. Remove the two valve access doors
2. Remove both valve adjustment screws
3. Remove the cam bushing retainer screws and retainer - you will need to flatten the tabs
4. Remove the cam - it will come straight out with the bushing
5. Compress the valve springs
6. Carefully Tap the valves until they come out of the valve spring retainer. There are two half-circle wedges that hold the valve in the valve spring retainer. Don't lose them! They bounce away like a super ball!
7. Remove the valve from the guide.
Reverse the procedure to reinstall. Notes:
Small needle nose pliers facilitate holding the valve spring retainer wedges.
Adjusting the valves can be done while the head is off the engine
Be careful that the cam chain guides are aligned properly when replacing the head.