I have two yerf-dog karts, one of them the same model as yours. I put a clone engine (196cc but demention wise same as a predator) to get more power than I could ever get out of the Tecumseh. It was a pretty easy bolt on swap.Engine holes lined up perfectly. I stayed with the stock jack shaft and clutch and it works good. If you can save yours, do so. If it's only rust, some sandpaper, elbow grease and brake parts cleaner can do wonders. The reason I say to try to save it is that the driven clutch should be 7" where as any new converter you buy will be 6" . It doesn't sound like much but what it does is give you a lower starting gear ratio w/o sacrificing anything on top end speed. With the limited engine power we have available it makes a difference in acceleration and hill climbing ability. I have 4 karts, all with torque converter two with 6" and two with 7" so l have 1 st hand knowledge of this. If you have the stock clutches driver and 7" driven REGARDLESS of condition they are very easy to freshen up. There isn't very many parts to them and there's a ton of videos showing how to do it. I realize you might be new this stuff but it is all really pretty easy to figure out and you can find a kart video to walk you through most anything.