Carb swap for a 97’ RM 125

If you want better than Keihin by a wide margin, there is the STIC Super X. Looks like a PWK, but internally it is quite different.

It's superior to porting bc it both creates significant low end and over-rev HP gains. Imagine a 125 that can get into the powerband at quite a low RPM, without always clutching! No more shifting on the bubble. It'll make you shift like a pro. If out on the trails, with little to no clutching, it will lug up steep slow climbs better than a 250RMZ. It's like having an electric motor assist.

The best value aspect is that you don't have to touch the engine or exhaust system. Maybe fresh clutch fiber plates and heavier springs is a good idea. 

Is the complete only available by calling George? Under $600?

I don't think HPRacing and Tokyo OffRoad have stock as yet. Price is under $700, which is lower than other less powerful aftermarket carbs. 

I've seen one for sale over at KTMTalk.com, BTW. I don't know if it's the long/short body, X or X2 version.

I threw a Lectron on my 98 RM125 that I use as a woods bike.

Love it compared to stock.  Very reliable.  Put it on at the same time I had a lot of other motor work done so hard to isolate what the impact was, but my 125 lugs pretty good in the woods and out on the track it has a pretty serious hit that if I were a good rider, I could really take advantage of!

 I’m old, lazy and sick of getting premix all over my hands swapping jets, so I love my Lectron on my ‘97!

Didnt have a problem with the stock carb on my 97.  Check your reeds and crank seals.

Boys, call them, I believe they have a new needle that has some voodoo for the low end grunt.

Xcelerator Metering Rods - Parts (lectronfuelsystems.com)

New metering rods.  Haven't pulled the trigger yet, but a very much maybe.