FYI Adam,... I agree with lemegacool smaw (stick) with e7018 lo hi is one of the stronger welds, if it's done right. but if your welding on a go-kart frame it's hard because welding with 7018 3/32'' it's better to run it up hill, and tring to get that rod angle right without long arcing , it's a headache, and welding on thin metal is hard and not so pretty!
I could see if you want a show quality go-kart tig welding is the way to go, it would take forever compared to gmaw (mig) ,not to mention all the prep work involed in tig welding,
My opinion flux-core is the way to go! it will keep you from going bald everytime the rod or tungsten sticks since you say your a beginner! plus its gasless don't have to worry about running out of gas in the middle of a project! you can buy a 10lb spool of flux-core .030 steel wire for about 80 bucks and make 5 go-karts! or a 2 lb spool for about 25 bucks! And if you are worried about spatter with flux-core or mig you can buy spatter spray at any welding supply store, just spray in the area you plan to weld! and simply use a wire brush and the spatter comes right off! Just remember more heat doesnt mean alot more wire in most cases, if your welding on a frame, if your heat range is 1 thru 4 set it on 4 and wirespeed range is 1 thru 10 set it on 4 with .030 and 3-3.5 with .035 you will notice alot less spatter just go slower! might have to do some fine tuning since all welder are diffrent! some ppl. learning think with a heat setting maxed out they think the wire needs to be! if mig welding aluminum i can see the ws being around 8-9. and stainless around 5-7 since the filler burns so quick, on a wirespeed range of 1 thru 10. on say a 110 volt 130amp!