The KT100 is a purpose built(racing), 100cc, free air cooled, piston port, 2 stroke racing engine. It is a poor choice for a fun kart for the following reasons.
1. requires massive, expensive, electric racing starter(looks like minigun minus the barrels)
2. Spinning at 16000+ RPM it require frequent rebuilds.
3. Runs a VERY fat oil mix with some expensive oil.