I tinkered around with this the other day. Bought 200 assorted spring kit from harbor freight for $5. One of the smaller strong springs worked out well. It’s a tight squeeze to get it on there, I had to be creative with some dental picks. Right side cover needs to come off. The frame is directly in the way of straight access. There is a notable difference in pickup from 0-1/4 throttle. I leaned out the idle jet and the bike seems to run great. Seems to have a higher top end as well, but that doesn’t make much sense. Probably just in my head.