Hi Widget!
I figure the best way to make money is to find a mower/trimmer/blower/chainsaw that someone has left on the verge or at the tip because they couldn't start it. If the previous owner is not mechanically minded, they may have given up without much of a fight or failed to seek repair from a professional outfit.
If you are lucky, maybe all the engine needs is a new spark plug, perhaps just a new flywheel key because it has been sheared and the timing is out, maybe a new pull rope is all that is needed because the old one is broken or jammed. Other problems might be that the carb needs adjustment, the diaphragm needs replacing and/or the primer bulb is broken (trimmer/chainsaw/blower). In these cases the repairs will be relatively minor/easy and cheap. However, there is always a chance you might need a specialised tool for removing components and you will have to spend more money. Another cost is having to replace the oil (a given), unless it's a 2-stroke.
It won't be worth it at all if the engine has thrown a rod and the crankcase is fractured or has a hole in it. But you might be able to use the remaining good parts to fix a similar engine already in your possession. If you have to change the coil, piston, rings or hone the bore to fit an oversized piston and rings, then your starting to talk about spending a lot of money, especially since you will have remove covers and this will often result in torn gaskets which can't be reused. So new gaskets are probably a given in these situations.
Unfortunately, if there are chassis and clutch problems with the power equipment, they won't be as easy to diagnose or repair until the engine is operational. Such components are costly to repair, and find/replace.
I would go for anything that is running a Honda, Briggs & Stratton, Kohler or Subaru. Stick with brands like Husqvarna, Honda, Stihl, Echo, Kawasaki(actually just about anything Japanese or commercial grade/quality). These hold their value, are very much sought after and revered. Stay clear of the cheap home brands, like Ryobi, Homelite, Ozito or anything generally manufactured in China (at this moment in time). I don't think you would even break even, if you tried restoring/repairing one of these.
Generally speaking, a complete overhaul or restoration from the ground up, to include paint, decals and original components, will be extraordinarily expensive (but it will depend on the condition of the mower etc.). Unless of course, you can do most of the work yourself or you are lucky to know someone in the game, that can point you in the right direction.
