So, why do you want to do this?
There is somebody on this board who has done this a few times but I don't know who. Long story short, no, it's not that easy. It's doable, but not a simple as you might think. I wouldn't do it unless you are totally sure your EFI system (or a major component) is dead. If it's just because you don't "like" EFI, I wouldn't bother. My plan for my 92 EFI is, if it blows up, drop in the entire engine/clutch/carb assembly from my 1990 EXT Special 530 - a better engine in every way except gas mileage. But we got through a full season with no show-stopping problems on the 500 EFI...the power is pretty underwhelming but my wife is a little girl and she went as fast as she wanted to and climbed some pretty nice hills. The sled reaches its maximum geared speed on a smooth surface (about 80mph). I rode it one deep powder day and it got me everywhere I wanted to go. But whether it's the lack of reed valves or something else, that indy 500 engine has terrible low-end power, bad midrange, and just barely enough top-end - and this is with the clutching nicely dialed. Looking at how cheap used sleds are selling you have to ask yourself if it's worth the trouble. People seem to really hate and distrust the old EFI sleds but I never had a problem with my older Honda EFI systems and they work the same way. I have no way of knowing the actual failure rate but it seems like anything that goes wrong in an EFI sled people want to blame the EFI. Well carbed sleds have problems too. Bad gas, coolant running out, overrevving (bad clutching), an air leak, an ill-advised mod, etc etc can blow up any engine yet if it's EFI it must have been that darn EFI. Anyway I think you get what I'm saying...just the old $.02
