This is good read for anyone building 2-stroke bikes. http://grubeeinc.com/index.html I know Don personally and very familiar with the YaunDong engine factories work. Always my engine of choice for the quality. Personally I have had enough of the EPA, they now also regulate MB's by TOTAL DRY WEIGHT of 44#! 44 pounds? Shoot, I have built on bikes that weigh that much before the engine kit parts! Actual real Skyhawk GT-5 EPA approved quality engines should hit the US shores any time now. gasbike won't get any, they have been abusing the Skyhawk name with sub-quality parts for 2 years now and still do to this day. For reference, a WD is a Wholesale Distributor. They buy in in 40' long cargo containers. RD is a Retail Distributer. I know of a couple but that is the jest of the 2-stroke world in the US. It's looking pretty glum and why I moving to 4-stroke and electric builds. Just beware of gasbike/kings claims of anything Skyhawk or GT anything, they aren't. Just a heads up from someone that actually knows.