Looking at possible build options and was wondering what larger size engines (either 2 stroke or 4 stroke) that people have tried with success for building of an in frame chain driven combination without tons of custom fabrication (don't have the ability to weld). What types of features would be helpful to have when looking at individual engines (for example clutch sizes, etc.) and helpful in determining if the engine would work well and fit if just a kit was purchased and the engine was bought separately. I would assume the main limitations to what type and power of engine are weight of the engine, dimensions of the engine (ones with larger horsepower may not mount properly within a bike frame), and overall cost. Can anyone point me in the direction of some examples of projects that involved larger engines than what typically come in the all in one engine kits? I have searched the diy forum and found some examples but many involve significant custom fabrication which I do not have the equipment for. I have a high quality steel mtn bike with 29 inch wheels and very nice brakes which I will be installing the motor onto.