Been looking at carbs for awhile, wanted something bigger than 15.88mm x 12.7mm 603 carb. Hugh at SD Scooters gave me a good deal on a new HDA 223 19mm purge carb. 19mm in the rear & a 15.1mm ventrui. I got a GRT 40 / CY42 purge intake manifold kit w/ a delrin spacer, and modded it to fit my Zenoah/Cag engine. Can't wait to get it on the engine stand w/ the Big Belly exhaust. Took 6 hrs of hard work to get it right. Still have to take it back off to put the boost fitting in.