Modern Vespa

My buddy has a 74 bajaj vbb that I've been trying to help him keep running. It'll fire up and run for about 5 minutes and then just die with no amount of kicking or bump starting gets it going again. The next day it'll start up again for another 5 minutes and die. There's spark and I've cleaned the carb completely twice and switched out the needle jet and float thinking it was flooding out. It doesn't rev up when it dies like it's running out of gas, just dies. The plug looks good to me. Wet but not black

Blocked tank vent?

Bad coil or stator coil that dies with heat?

Blocked tank vent is a good idea for sure. I'll take the fuel tap out and clean it out.
If it was a coil wouldn't it not have spark when I check for spark after it dies?

You can just run with cap open, it's not about the tap itself.

On the coil maybe but maybe it just gets weak.

There's a small pin hole in the gas tank cap. Opening the cap and seeing if that lets it run will let you know if that pin hole is clogged or not. Quick and easy to check that at least!

Did you check that fuel goes at normal speed through the fuel hose ? It could be a blockage from the tap due to dust, residues…

Mine did similar before I replaced the coil. It wasn't 5 minutes… it was more like 10-15.

It this point I'm pretty sure its the coil.
I have spark for the first 5 kicks and then nothing... going to switch it out to one I have on another bike that runs

I switched out the cdi and external coil that I know are good and still no spark.
I think it's time to move on to the stator?

On other more typical situations the black pickup coil is at 8:00

(Cue negative remarks about Bajaj electronic ignitions from the crowd)….

Does anyone have another stator that'll work for sale??

from what I know, the bajaj ones can work but often have electrical faults that keep them sidelined. usually a bunch of people chime in the moment they see it's a bajaj system and tell you to ditch it. I have no experience with them yet, but it's just a pattern I've observed.

people in the know will be along soon.

This one?

So I replaced the stater and flywheel and it fired right up. It must have been the ignition coil on the stator.
This is the set up I have on there now. Thanks

Should I be concerned that the flywheel doesn't have cooling fins? I've never seen one without them.

As OP has now demonstrated, we make those negative remarks for a reason. There should be a (plastic) cover that bolts onto the flywheel. Check you old flywheel and you can probably remove it off that and re-install it onto your new one.

This is the first time I've seen a Grade D repair part from SIP. Doesn't seem very reassuring but they do state it's adequate. Hope it holds together.

SIP now make the Vape for the small cone crank, which is money well spent if you insist on running an OG crank.

of course there is. Thanks

It's all good