I've never been to Kunming, but I've lived in Shanghai for the last year and while a fair amount of people are riding without plates, it isn't really safe to do so.

I'm not interested in riding without plates, however I am wondering if it is a common thing to do as it would also likely show that license enforcement wasn't so common either.

There are some issues right now that leave me unable to obtain a Chinese drivers license, and at best I have my Canadian license. I'm not interested in driving cars, but I will likely need or be bringing a motorcycle.

Is it common to see motorcycles without plates? How safe would you feel riding a motorcycle without a Chinese license (but with plates)?

Do you ever see motorcycles/scooters getting pulled over? Or motorcycle police? Police traps? For anyone with motorcycles, do you ever get pulled over?

Yes, police traps are everywhere, these days. Recently they have started to co-ordinate via radioing ahead, to stop motorcycles in the city.

The downtown area of Kunming - within the 2nd ring road (?) is off limits to motorcycles during business hours.

If you're a foreigner riding a motorcycle these days, you'd BETTER be licensed. Riding a motorcycle or driving a car without a license has always been a deportable offense - but with the recent crackdown on terrorist activities within China - the PSB are generally more rigorous with enforcement. If you can't get a Chinese driver's license for now - you can try using the international driver's license under the pretense of ignorance - but you still risk deportment and potential confiscation of your bike.

For city driving - just use an e-bike. If you want to tour outside - probably less problematic - however, again one should respect the laws of China reasonably rigorously.

I am not sure how motorcycles are classified.
The 125cc and above have licence plates here. I also think there are restrictions on where they can be ridden.

However, I see gas scooters that were not carrying a licence plate. Not sure, but they may be under 50cc and LPG.
Ebikes are the other option. Some of these have a very good range now.

It used to be ignored here, but now it IS enforced. You WILL be stopped and, if you do not have a license, they WILL take away your motorbike, and possible arrest you. Do no chance it: just get a Chinese motorcycle license.

or ride something legal that dont need a licence.

China is probably* the same as other jurisdictions in that if you are not licensed or otherwise driving illegally then you are not insured. You'll not be covered for third party liabilities that could run into hundreds of thousands of dollars. For example, if you killed or maimed someone.

* What proportion of drivers are insured, even for third party liability?

kill someone and it usally costs 60k rmb. unless the stiff was from a rich family, and even then.

@NNoble All motor vehicles that have current registration have 3rd party insuarance but the standard max payout is 50k which isnt so much thesedays.