Two things will kill a CVT, heat and/or dirt. The variator has fins on it that pull air from the front inlet, pushes it past the clutch and exits out the back. The front inlet should be unrestricted with some provision to filter the air. The cover not only acts as a shield to protect the cvt system but also forms a path to run the air to the clutch.
The snowmobile guys don't deal with the same issues we do. Hard to overheat with the snow temp. mostly below freezing and not much dirt and dust on a snow surface. This pic shows a good method to get more air to the clutch if you have an heat problem. use a howet cover with a removable plate at the clutch. replace the plate with a screen and filter

The 127.5 is ok,i have a 132 ill put in when i open my exhaust up.on four strokes the plug is usually white,you just dont want to be so lean u melt the center porcelin.mine has a lite tan brown on about half of the plug,so its a tad rich wich is ok.im already thinking about a bigger carb,it sounds like the jetting is about the same for the bigger carb.not sure where ill get the carb,mabe ebay if i figure out wich one to look for.i dont remember if you have switched to a 39 tooth sprocket,it makes a gig difference in how easy it is to take off,helps save the clutch.i cut up a paint strainer from lowes to make my clutch cover,just used washers with the stock bolts.watch out for the nuts that hold the exhaust to the head,mine fell off and ended my last trip.i dont see a problem with running with no snorkle,if there was a lota mud that would be different.i also considered drilling a hole in the bottom for any dirty diaper to fall out of.i think heat is the real clutch killer.and the gearing and lack of power,thats all!

I put a snorkel tube and a pre filter on that to pull cooler air from higher up and away from the exhaust. I managed to go 2 years on the stock belt.

RH

Fireman,thats good,i noticed yor buggy has a new clutch,how long did the stock one last?,you also have made mods for more power.i bought a spare belt but my stock one has no wear,i dont think it has ever slipped,when my buggy wouldnt move i stopped before burning things up,well mabe only burning a little!i would back up and gun it forward.i did say if i lived where there was a lot of mud i would do things different.i noticed a lot of talk about a snorkle,but not much about a large exit tube snorkle to help dump the heat out!i think a fan with the intake snorkle would be good also.this is an important subject,i think folks buy a buggy and with the stock gearing and clutch setup go and burn their clutch up in short order,souring their opinion of chinese buggys.the clutch shimming article is very good to learn more about this.