You need to pull off the side cover and check that the kick start mechanism was put together correctly, and that the return spring is located properly. Unlike the NSR250, the 250 has a missing tooth on the kickstarter engaging gear so it's impossible to get wrong. However, the shaft may be bent, or one of the springs may have gone walkies.

As for engine noise, well, none of the NSR150SP's I've seen have been very quiet! Even AP Honda say that some knocking is normal! My old race NSR150's didn't knock though and made nearly 40hp, so it's as much down to how you put them together.

Oil quantity is 0.7L at change & 0.8L at rebuild. SAE 10W-40.

Oil pump has a mark on the pulley which should align with a mark on the pump at WOT.

Can't really remember the procedure for setting the RC valves, but if you rev the engine up and down you'll see that there's high and low marks on the cylinder. Just adjust the cable until the high lines up at high rpm. It might even be that at idle the valve moves to the set position which is where the cut out in the pulley should align with a hole in the cylinder.