I believe 162 main 48 pilot is correct for stock 2001 RM250.
Depending on what it is doing, you probably need to move the clip position. Typically in hot/humid Ohio summer you need to lean the bike out, which means dropping the needle (moving the clip UP).
At Mid Ohio this past weekend, I needed to have my needle clip all the way up (dropping needle all the way down) in order for the bike to run right. Monday I immediately ordered a leaner needle for the bike.
Because the OEM needles were not available for my '98, I ended up ordering a "kit" from
https://jdjetting.com/
Their kits are a little pricey, but they also come with the ability to have them help you out. I've used their kits before for other weird bikes like Yamaha TW200 and man it ran great. I talked to them for a bit on the phone yesterday and they are very nice and helpful.
Here is their kit for your bike:
Main jets Multi-taper needles Detailed instructions
jdjetting.com
But before you do anything, I would check clip position on the needle and possibly move it up a spot to drop the needle and then try the bike out.