Welcome to the forum.
It is now 15 years since we had one of the air cooled KTM 50's, so I struggle with recollecting much of that motor. Here the bike/motor to get you started: 1999 KTM 50 SXR Pro Senior OEM Parts, KTM World
Also do a search here: Manuals for KTM bikes (updated 29 Apr 2021) for a manual for the bike.