Quote:
Originally Posted by Titanosaurus
), I am an auto mechanic, and although similar, I don't have to tell anyone here that it is NOT a car
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True it is not a car but you are a mechanic so you understand the basic principles of the internal combustion motor. The mechanics of this motor are a little different but the same principles apply, air, fuel, spark.
From the symptoms you descibe I'll go through a few items.
you altered the fuel petcock so look at this first. the petcock is activated open/shut by engine vacuum. when vacuum is applied the valve opens to supply fuel, closes when motor is shut off. A good safety feature but prone to malfunction. check for vacuum leaks. The slightest leak causes eratic carb behavior.
Check the tank and fuel lines for trash. replaceing with clear line helps to observe flow. ethenol gas will eat up those cheap chinese rubber lines so watch for this or replace with a ethonol friendly line and filter.
The main jet at 114 is about right for a motor with stock air and exhaust systems so go back to a 114 to get a base line to tune. The carb is a Kehein clone 24 mm cv type. The main jet is a Kehein # 99101-393. The pilot jet is a N424-21. Any cycle shop can get them for you.
Disassimble the carb and clean it well! A lot of low to midrange problems are caused by almost invisible trash in the pilot jet. A new carb can be had from e-bay for aprox. 30 bucks if you wanna go that route but it will have to be jetted for your buggy so save your jets.
The choke or actually a enrichiner is another cause of problems. it is not a choke as such it closes off the air supply but rather gives an extra amount of fuel instead. it is a extra circut in the carb that is controled by a needle and seat that opens for more fuel when cold then closes as motor heats up. this enrichiner need electric power to stay closed. There all kinds of info here to show the proper procedure to check it .
Check All electrical connections! A poor connection can cause malfunctions in the CDI contol unit or the coil that can give the same symptoms as a bad carb adjustment. the china wiring circuts on these buggys is screwed up at best, A bad ground at the switch can cause ignition problems. Most igniton problems show up at higer rpms but you haven't got there yet. you got spark, so focus on the carb systems first
there's tons of info on the web about these carbs and motors in general so read up a little ,get familair and ask us a ton of questions