I have a Kinroad Sahara 150cc that for some reason burns out rings.

I have just put in a new set of rings, the buggy was running perfectly, no smoke, good power, after about 2 hours of running it started blowing smoke again,

After about 5 hours of stop start running it's blowing lots of smoke again, although I haven't pulled it down I strongly suspect the rings are gone again.

How important is the quality of air filter, I was riding in a dusty environment, this buggy has the stock air box, I have seen on forums that the air box should be replaced as they are dirty diaper.

I am thinking that maybe the engine is getting dust in the cylinder due to the poor air box and wearing the rings.

My options at this point is to replace rings again and install a better air filter as see what happens.

Any suggestions or advise would be greatly appreciated.

i don't know what kind of stock filter you have . mine had a thin foam filter that did not seal good in box and didn't keep dirt from going through filter even when it was oiled.luckly i caught mine in time. a good air filter is a must i think on any engine.
the stock air filter might have been fine on a scooter but there not in the dust and mud like these buggys.
my self i would up grade filter.

pud

further to this, when I replaced the rings they were from a chinese supplier could it be that they a poor quality ( soft ) set of rings.

Should I try a set that maybe be harder.

Sounds like your rings, but not sure. Dust has to be stopped, but we have a flat track we ride on that gets so dusty that we have to stop because we can't see where each other is at, and my original rings seam fine. I did have a defective valve guide on the 150 that made it smoke like a mosquito truck. Check your compression before you tear it down (for you funnyman). If rings are wearing out that fast, something other than dust by-passing the filter is probably causing it. What color is the smoke? Is your oil level dropping in the crankcase? Have you re-adjusted the valves? I wouldn't put in harder rings, if you could find them, because we don't know what the cylinder walls can withstand.