Installed the new petcock tonight. Filled the tank full with pre-mix and my daughter tried to start it without luck. Twice it sounded like it was going to go briefly, but then nothing. When she learned last fall in a course, it was on a bike with an electric start. Tonight was her first time doing a kick-start, so she was a bit hesitant.

These were her steps:

1. Turned the key to "on"
2. Turned the petcock to "on"
3. Turned the switch on the throttle to "run"
4. Then struggled with the kick start. Her foot kept slipping.

Anything steps she might be missing? Should the choke be open? Should she do anything with the throttle when starting?  Can she flood it?

Any tips or guidance would be greatly appreciated.

Thanks!
 

Choke needs to be on when starting cold, and do not give it any throttle when l kicking it. Let it warm up for a bit, then turn off the choke. When starting warm, just give it a little bit of throttle when you kick it with the choke off. If the bike's been sitting for a little bit after riding, I always feel the fins to see if it's cold, and if so I put the choke on to restart it.

So I've never rebuilt the choke on my '72 CT2 and it doesn't like to start with the choke on, probably because I never have. Guessing there is an air leak around the rubber. What with warm California temperatures (even down to freezing though), I've had the best luck kicking it over with the key off and throttle just barely open 5 times, then doing the same with the key on and she tends to fire right up.

If the choke isn't enrichening it the problem is more likely a blockage in the choke metering jet in the bowl or in the tube that reaches down to the jet--i think. Unless im misunderstanding the problem.

Yes, choke on to start from cold.

AS RT325 alluded to, there is a tiny jet in the float bowl and this can get blocked.

Here's a link to a random one on fleabay and the jet is at the bottom of the "tunnel" cast into the bowl, not the brass pipe (see 3rd photo). Squirt some carb cleaner, petrol etc down there and you should see it dribble out of the jet/hole at the bottom. If blocked, clear with something like 0.4mm wire.

Yamaha DTMX 125 2A8 Carburetor Tank | eBay

Darinm, I'm not far from you near the beach in Huntington (very temperate climate), and my CT-1 starts cold on the second kick with choke on, no throttle.

She got it started! Posting a video as it was making a loud, knocking noise. We weren't sure if it's a normal sound or not.   She thought not having the clutch all the way in might have contributed to it? We didn't want to fry the engine, so we shut it down. It also shot out a good amount of smoke from the exhaust. Is this normal?

drive.google.com/file/d/1WrvODVmLRY7m5fo...HY0/view?usp=sharing
 

Sounds ok to me, although maybe a bit muffled, as if the exhaust needs burning out?

Yes, loads of smoke on first start is fairly standard on two strokes that have been stood - a couple of good blasts down the road should sort it out. Thereafter, I would expect a light blue haze and a gorgeous smell!  

AWESOME! It sounds fine to me too, just sounds like a Yamaha. That's a really nice looking bike too! Once it warms up and you turn off the choke it'll sound a bit different as well.