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Hey guys I have a 1986 mighty max. I want to ensure the stock carburetor is setting screws correctly position. Is there even away to do that? I bought a manuel repair book but how I understood the book it was to adjust if it hadn’t already been adjusted. Not sure if the previous owners had messed with the carburetor. Also I’m having a lot of black tar coming from the tail pipe. Any ideas of what could be causing that?
Hi and welcome to mightyram. First up, what symptoms is the engine showing that makes you think it might be running lean? If your plugs are fouled it could be from a number of causes. It is way more helpful to identify what is going on before altering screw settings on the Mikuni - it is not a carb for noobs. There could be (and most likely is) air leaks in the carb vac control module. Generally a coked up exhaust indicates oil burn. What is the oil looking like? Yeah I know this is a barrage of questions but it will save you a fortune in migraine meds if you follow a process of elimination.
Rpms seem high an the mad an sas1 screw just iffy on their positions. I can get the engine to idle fine but jus not sure about the other two. An it seems to be running rich.
Honestly I just want to know if there is a way to reset the adjustment screws
Back off the throttle stop screw and the fast idle screw (the adjuster under the throttle cable linkage - do NOT remove that screw as there is a captive spring in there and you will have to be extremely lucky to find it if it drops out). Check the adjuster for the throttle cable to ensure it's not loading up the throttle and you have a little play on the cable. Wind the throttle stop screw back in until it touches the throttle cable linkage and try to start the engine (this needs to be done from a cold start so the fast idle can be set). Wind the fast idle screw in until you get an idle rpm between 1150-1250. Try not to apply pressure on it as this will fudge the idle. Let the engine warm up and check the idle (should drop back to 850-900 rpm). If you've got your carb sorted out, now would be the time to reset your ignition timing as the ignition relies on the engine idle being correct. Some carbs have a sealed idle air bleed screw which can't be monkeyed with but the usual way to adjust them is to wind it in all the way gently until it seats itself, then wind it out 1&1/2 - 1&3/4 turns.
Honestly I just want to know if there is a way to reset the adjustment screws. Because someone moved them
Attachment 20224Do have this identified correctly