checking valves myself?

Depends on how mechanically inclined you are. Theres risk of dropping very small parts into the bottom end. As well as timing the motor wrong and causing the piston to hit an open valve when you kick it over.

With that being said, if you take your time its not hard. Just go one step at a time and take your time. Usually you can get a few uses out of the valve cover gasket. Youll need silicone sealant for the “lobes” of the gasket. I would get new orings that go between the head and cam cap around the spark plug hole though. If they fail youll get oil in your spark plug hole and it will leak out the side of the motor.

What bike?

Paw Paw

No special tools needed just to check them except the correct feeler gauges.
You will need to be sure the engine is at TDC on the compression stroke.
You will however need shims if they are out of spec's.

Paw Paw

Do you have any riding buddies that work on their own bikes? They could walk you through it. I have taught several people how to do it.

Checking clearance is the same for all but Shim under bucket adjustments Is a lot more work and there are tools that must be used. Inch pound torque wrench is a MUST! Tiny Suction cup or a tiny Magnet to pull the bucket out is a must. Tiny magnet also works for pulling the shim from the bucket or valve spring assembly.

Take measurements on all valves and write down what each clearance is minimum to max and write down intake, exhaust, right, left so you know whic needs a different shim. When taking cams & rocker assembly off and pulling the buckets keep notes of which is intake, exhaust, right, left to adjust each shim depending on what is needed and properly reassembled in the right place.

FYI: Also understand that most used shims will show wear in the area where the valve puts pressure on them and can thus throw off your measurement calculations, unless you can measure said indentation and work them into your calculations.

Paw Paw

Its super easy If you can do simple math you have the shims and a feeler gauge you can do it no problem. I never re seal my valve cover gasket and it has never leaked on 3 different 450s