Beat monks in leaper race was a mission in Jak 3. Seem demanded the dark eco crystal that Jak took from the crashed dark satellite in the earlier "Unlock satellite" mission. He wagered a light eco crystal in return if Jak would race against Seem's monks on their leaper lizards.
For this mission the leaper lizards will be much faster than normal, being able to knock down wastelanders without any trouble. The other racers are pretty good at this as well, meaning the only thing you can rely on is to cut as many corners as possible and knowledge of the track beforehand. There's several tricky jumps and turns where you need to be quick to turn the speedy leaper in a different course. You will have to hit all the rings or you'll fail the mission.
The track itself starts at the northern end of Spargus, makes a couple turns here and there and then leads south past the Spargus Palace and through the market area. From here you'll make a couple more turns and jumps in this southern section and eventually end up at the finish line at the market.