RE: MAGNUM with west 50 running on when throttle shut
Guys:
Sounds like MDS and Magnum use the same carb. Had several MDS engines with the same problem, air leakage. Put a ST carb on one, stopped the problem and ran great. You might try some of the aftermrket carbs like a racing version of the perry, or the best of the best, the Jett (sports Jett) carb. Bet you could talk Dub or Bob B match you up or mill you one down as necessary. Jett and crew are great guys and will help whenever possible, even on a Magnum which is gonna self destruct at any moment!