In the picture locate #12. #12 is what is called a dash pot. All carbureted engines have a dash pot on them. With any carbureted engine, if you throttle back to quickly, the engine can stall out. What this dashpot does, is when you throttle back quickly, the dashpot prevents the carburetors from closing to quickly. The dashpot holds the carburetors linkage open and then allows that linkage to slowly closes, instead of just slamming shut. If the carbs linkages and throttle plate slams shut quickly, the engine stalls. If the linkages close slowly, the engine returns to and idle without stalling. Ultimately your problem is going to revolve around the carbs. You can have a sticking dashpot, sticking carb linkage, or sticking carb throttle valves. In the shop what we would do is pop the linkages off the carb and first make sure that the linkages, as well as each carburetors throttle valve (the butterflies) are not sticking and jamming up. If they are sticking or jamming up, then you need some oil/lubricant in those areas. If the carbs throttle valves open and close freely, without sticking or binding, then you have a bad dashpot, holding the carbs linkages open for to long, and not allowing the throttle valves in the carbs to slowly close. Does that all make sense to you. I do want to make sure you are happy with my service before you go. If you had a further or more specific question on the issue by all means feel free to ask. If not, Just in case you do not understand the way the website works (and some folks do not). You do have to put forth a positive rating in order for it to credit me for helping you. When ratings are not done, the website simply keeps your deposit and they will not credit me. The ratings box is located at the top of the screen. To rate, you must select the star you wish and also confirm it. Please let me know if you run into any problems or errors when trying to do it. If you do have a problem, or if you can not see the ratings box which is at the top of the screen. Please reply back "I rate Jason's service _______" and fill in the blank.
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