Welcome to the forum man, and that's a great looking Saltare. Tres bien!!

Everyone is pointing the right direction on your engine not being able to rev up unless really warmed up. You may be dumping too much fuel, running rich. When it runs, does it smell like pure raw gas from the exhaust? If so, that and your choke may need to be adjusted would cause this problem to happen.

If your engine is running rich, it's pumping too much fuel into the carb. It won't affect it much when it's warmed up because the choke is full open. But if your choke needs to be adjusted to open earlier, or isn't opening electronically at all, that will definitely cause your problem.

When you look for fuel in the bowls, check your choke. It should be electronic. Turn the key, and watch the choke open. It should go from closed to open in 2-3 minutes. 5 at the most. If it takes too long to open, and you're running rich, those two combined can kill a motor till it warms up. Nothing really wrong, just stuff needs to be adjusted.

Keep us posted!