If the engine is only cranking but not popping, backfiring etc. Then like T-Boss 410 said, the injector could be bad. Massimo does not have a inline fuel filter, just a screen. This apparently leads to a lot of bad injectors. A common bad injector symptom is the motor will start and idle but fall off under acceleration. In your case, there is nothing, so let’s look further.
Check the spark with a GOOD TESTER. I’ve been an equipment mechanic for 30+ years and I can’t tell you how many times I’ve seen a spark plug fire when laid on the engine block THEN NOT FIRE when it’s installed and under cylinder pressure.
Is the fuel fresh? In my shop it’s VERY common for flat fuel to cause a no start
If you truly have good spark and fresh fuel then try this quick trick.
Take the air filter off and shoot a little carb cleaner or starting fluid into the intake. Then crank the engine over....
1) Still nothing. You have a valve issue or a compression issue. (It’s not burning the fuel)
2) Motor starts then dies. The Fuel Injector is most likely plugged or bad. (You’re not getting fuel into the cylinder)
I hope this helps.