Predator 79cc Won't Start,

I finally got the engine mounted and everything more or less solid.
But now the engine won't start.
I seem to get a good jolt with the plug wire, so it should be giving a decent spark. I suppose the next step is to make absolutely sure about this, but I don't think this is the prob.
It has gas in the tank.
I've only used the engine for maybe 3 miles (5 km). I stopped it when I realized the pulley was broke (now replaced).

The arrangement has little to do with the engine, but I'll explain. The engine is on a ladder that pivots (under seat a bit forward, see the bolt with the large washers) on the bike frame. The clutch is accomplished by using the clutch handle to move the engine & roller off and on the rear tire.
The white tube in the rear is just fall protection for the engine.
The brown almost vertical tube just holds up the engine, keeping the clutch disengaged, temporarily for riding with a dead engine.
The red tape is something I just put on. I was adding insulation.
The sheet metal covers the hot muffler.
The white rollers keep the ladder in position when needed, but it's pretty strong.

But the problem is that it won't start.
When I pull the start cord, it feels like decent compression.

Could the valves be bad this soon?

What should I test next?

It's now starting. I posted too quickly.
When I re-mounted the engine & roller shaft bearings after changing the pulley, I put things out of line and it was dragging on the engine too much for a start.
My mounting methods are developing as I learn.
I use holes and elongated holes to mount the engine & roller shaft bearings.

Next time I make square tubing ready for mounting, I'm going to cut slots instead of drilling holes. In that way, I'll have more latitude on position. I'll drill a hole at each end, then cut out the metal between.

Although a bit dangerous, the bike is working acceptably now. Actually, my brakes need new disks and the clutch needs refinement, but I can, indeed, ride using the engine.