My front carb has the small mixture screws like the ones in dragonslayer's pictures. They turn too easy. That's why I think they may have moved out of adjustment. My front carb is #4742, and it never had the plugs to hide the small mixture screws. I started adjusting the front/rear carbs Air/fuel mixture by turning all four screws out 2 full turns, as stated in the dual four carb setup article mentioned earlier. I hooked up my vacuum gauge to the rear carb to show me the highest vacuum setting, 2 turns is very close to giving me the most vacuum while idling at 900 rpm's. I didn't see where I could hook up the vacuum gauge to the front carb, so I adjusted it to what sounded like the smoothest and best idle. What I have left to do is to make sure that I have 50-100 rpm's from the front carb and then readjust the rear carb idle.

Meanwhile, back to the small front idle screws, I think I will try to find regular mixture screws and use springs on the screws to offer some resistance against movement, at least for the time being.

By the way, I purchased the carbs 17 - 18 years ago from R. D. Katter. The front carb has never had plugs to cover the front mixture screws. Once I know the adjustments are correct, I would like to cover the mixture screws like they are supposed to be,if I can find the correct plugs