I got a mds 40 as my first engine but it kept cutting in flight.(when it got flying[:@] ) Im now on my second mds40 chich runs really well on a 11x7, enya no.3 plug and 10%. I find the carb very sensitive to adjustments. When you do get it set DOBT change it. it shouldnt need changing unless you put it in another plane. As for the low end start the engine and run it up then let it idle for a minute or two. Then rev it up, if it dies open the low end needle 0.25 of a turn anticlockwise. keep doing this until it throttles well. Also the engine takes a lot of running in.
Tom