My previous reply was that MDS have a problem. Most of mine stalled in flight, either every flight or most. I build my own engines for fun and therefore think I know what to do to cure problems. Unfortunately my larger MDS sizes, 148 and 58 stop frequently and have resisted every attempt to cure them. The 148 is better with an ASP 1.08 carb, which fits straight in. The 58 is better after sealing the slow running needle with gasket seal. Also the throttle stop screw. Better but so sensitive to the correct mixture that it needs re-setting almost every flight. I have given up for the time being, but still keep looking at the lumps and trying to find a cure. My pal also bought the 58 at the same time and fitted it to WOT 4 the same as mine. He is still using it and after the above sealing session has managed at least one flight when it kept running! We still have the old style carbs as the UK agent is not so willing to replace them free and the cost is almost as much as we paid for the engines.
Calculating the cost of using the 148, I found that stopping in the wrong place has cost me a scratch built Ultimate, shredded through a tree, a complete fuselage re-build of my WOT 4 and a lot of dead engine landings causing minor damage. Since fitting more reliable engines I have not had one stoppage or crash caused by the engine.