Most of the time to get a small engine to run good, is by cleaning the carb.One time I was in Colorado visiting my wife's grandparents. Her grandfather could not get his lawnmower to run very well. I cleaned his carb and he was ever so thankful. He is a former machinist who also thinks I should go for it. Another uncle who is an entrepreneur says I need to start a side job doing something I already know how to to and do it well. I am an excellent trouble shooter and I know I can find the problem and repair thing in a short time frame.
When I see someone hasn't run their small engines for a while, 80% of the time it won't run right after it fires up on the start cycle.
The primer did inject the fuel but the main metering jet isn't providing fuel due to it gumming out or clogged up and needs a teardown and a good cleaning from a can of carb cleaner or starting fluid.
And for 2-stroke, you need to tell them to drain the fuel and run the engine til it dies to clear the fuel lines and carb of the remaining fuel.
I tore down and rebuilt a 5hp 4-stroke lawnmower engine when I was 12 yrs old. Why?
Someone poured engine oil into the tank that had the cap marked for fuel
I would invest in a 220v air compressor with a oil sump. The capacity size will be determined by your workspace size and how many air tools you want to run off of it at once. Those impact guns will come in handy in removing stubborn bolts and mower blades bolt.I already have most of the tools as I have already rebuilt several small engines including a Robyn golf cart engine. I will need to get the specialty tools but I can get thin one at a time as the need come up.
Also various flywheel pullers, crankshaft splitters, hydraulic presses, kits for measuring oil content in fuel, heavy duty battery chargers with 'engine start' feature for those that have electric starters... And depending how big small engines equipment you may run up to...ie mid sized John Deere tractors and uility tractors, I would get a engine hoist or a forklift truck with attachments for removing heavy arms and wheels from the tractors.
And you will be dealing with annoying problems more than once in a while, ie no 2 stroke oil mixed, explaining that it requires 2 stroke oil and not plain gasoline alone..and the engine is damaged for extenstive repairs...those are the idiots.
And yes once in a while you will get a generator that won't start... only to find out the oil level switch is defective and unplugging it will cut the ground to the engine block and igition will fire on the start stroke.
I don't know much about your area...but here alot of spanish 'landscapers' or lawn 'service' come in and talk spanish and try to tell you it won't start or run. Or like a belt is not tight?