Andy wrote:

kangranwang wrote:
I've done 50 miles regular riding, and 10-20 miles high rpm(10000+) riding. No big issue found. Carb was cleaned. It was just that the mechanics suggested another pilot jet to increase the idle rpm...

https://tech.nsr-world.com/nsr250/all-nsr250/nsr250-stock-carb-settings.php

Stock pilot jet is #38 across the board. We've actually found we've often needed to go up a size on the pilots with the latest fuels.

My mechanic guy mentioned size 38 as well but he thought it should go 1 size smaller in order to reduce the carbon build up in the plugs. What do you think?