if yout dont have all the gear you will need a few switches. the power comes in from the alternator from here it goes to the kill switch and the fuse box, the red wire is basically the common. from there its pretty easy to follow. if you need i can redo the diagram for just the engine ignition.
the lifan 125 would be alot faster. buying a semi auto would be best for a cart tho. they put out roughly 10hp at stock. buying a larger carb and a larger exhaust you gonna be pushing 12-13 hp.
as Anderkart said , its gonna be easyer to mount the 13hp. But if you can get a semi-auto lifan. its gonna be better. they both put out roughly the same power at stock but the lifan has 4 gears to play with. and is easyer to add more power too.
I use to run a Loncin 110 in a quad. they good little engines, however the semi auto clutch wears out fast, the bore is an odd size and hard to come across (in australia) and the electric start lets just say "its not very good". The lifan is the better buy by far. especially for the extra power...
anderkart has the same idea as me. another way would to take your spark plug to a nuts and bolts shop and get a thin nut that screws on to it . then screw that on and screw it into the head. then tig-weld the nut to the head and fill the gap .
a diesel engine would be your best bet, no ignition system to worry about, just have to worry bout the engine cooling down too much. but if you cbs that. i have been toying with the idea of using a motor bike stator and magnetto as my ignition system and using the cdi and everything. all you...
im running a 28mm on my 5hp mitsubishi engine on my gokart. and a 28mm on my YZ140 . its 200cc id go with the 30mm, its gonna provide plenty of flow for that engine.
most dont unless stated, which is abit of a pain. i picked up a new engine for my kart today and gotta fab the exhaust and mounts . its similar to this one...
the oil the engines are shipped with is basically run in oil, its there to run the engine in. but it is better to change the oil straight away. i have run engines with this stock oil for 7 hours running them in and havnt killed any. also if you want more power go for a better carb and high flow...