Really hard starting

[endo12]

Hey there my friend owns a tow lot and got a 1993 seca ii that had been dumped two or three times pretty bad. So I came up with the idea that we should make a go cart out of the frame and motor. I pulled the body off of my old parts vw beetle I had sitting behind my shop so after a lot of trail runs and welding I got it all straight and true. Really nice motor after I get it warmed up, which is much easier said then done. It seems to only fire on one cylinder and fouls the plugs out really fast. The first little tap on the start button it runs great for American, dies, and goes back to putting on 1 cylinder. The bike has been like that before I cut it all up. Does anyone have any good ideas, or ever experienced anything similar? So far I have cleaned spark plugs, oil change, stays on a battery charger, took carbs out and cleaned them, air cleaner is clean. Any help would be very appreciated. Thank you