You will have to remove the valve cover, you will need feeler gauges, not sure if you would use a ring spanner or allen key to adjust, or both, haven't seen this engine, so not sure of the valve specs and how to setup for adjustment, I would expect the engine to have an automatic valve lifter for easy starting, so I would assume that you would rotate the flywheel a couple of inches past TDC on compression stroke so the valve lifter is off cam and allows the valves to be seated for adjustment.
If you don't have a flywheel puller, then you replace the flywheel nut back onto the shaft thread and roll the nut down until the shaft thread is not quite flush with the flat of the nut, this is to protect the thread and nut thread when you get your BFH to "squarely" hit the nut and shaft, you will also need a tyre lever or large flat blade screw driver that you will place under the flywheel and onto a solid place on the engine to place leverage against the flywheel, if your engine has electric start, then be careful how far under the flywheel you place whatever lever you use, there is a charging stator under the flywheel if electric start.
Your best bet would be to either buy a puller or hire one to pull the flywheel.
I'll see if I can find the valve specs for you.
