I'm trying out the VM12 on my first CG engined bike with a Amazon bought Kaxton 48cc. Since the smaller engine should be similar to the 50 cc Yamaha kids bike in fuel draw and metering.I have been running one of those on a Flying Horse for several years now. Its a decent carb. Was way rich as received. Remote choke is nice as is an idle circuit.
I tried the 12mm version of the Bing figuring I would loose some top end but gain better response and low/mid range. Was just too small. The 15mm may be just right. I have since swapped my CGs to pumper carbs so this one may never happen.
NT had the best low end power, but the runtong is a close contender now after some jetting. For sure the runtong has better mid and top end hands down. The NT carb must of warped the body from the heat and stopped working the slide, the brass hammer made sure of body had no slide. Runtong runs good but wont idle which is fine for me. But wonder how a real Dellorto would run over the runtong. Or any of these carbs listed in this thread.I have tried the Runtong, not much of a fan. Neither am I of the NT. Was just determined to make one work. Get something with an adjustable idle circuit what ever it is.
Jaguar at the other forum has some fixes for the Runtong.
I like the idea of adjusting the NT with a hammer!