While doing research on belt temperature sensors, it alluded that belt temps will run higher if you snorkel the housing and if you are on a long downhill run.  I can understand the longer length of a snorkel impeding the airflow since there is no fan but that shouldn't be much. I however don't understand how going downhill causes high belt temps.

[2015 Z Force 800 53/Trail EPS]

While doing research on belt temperature sensors, it alluded that belt temps will run higher if you snorkel the housing and if you are on a long downhill run.  I can understand the longer length of a snorkel impeding the airflow since there is no fan but that shouldn't be much. I however don't understand how going downhill causes high belt temps.

There is a fan...it's the fins on the back of the primary and it moves a lot of air depending on RPM. I'm going to say neither statement is true. If there is no airflow restriction..such as using a 3"+ intake with NO filter, and the source location is the same temperature, and the discharge is also 100% unrestricted, the airflow volume and temps are unaffected. Going downhill only causes the clutches to shift-out a but farther thus slowing the primary RPMs which slightly slows the air movement...but downhill also puts less stress on the belt which means.. less heat so...I call BS on those that told you this. The most heat is produced from the belt and clutch sheaves when it is under load and at higher RPMs.

A lot of people use 2" PVC and that will be restrictive for both sides because for example on my Z, the intakes calculate-out to just under 3". I went with all 3" ID turbo/inter-cooler pipe while leaving the discharge alone. I did add a dry-type filter which even clean had some slight restriction but not enough to worry about. When it gets plugged the temps go way up..that's why I installed an inline booster fan..to help cool it enough to get me back to camp. That didn't always provide enough so I then added a Donaldson Top Spin prefilter/particle separator which get about 60-70% of the dust out. Now I can ride all week and more without having to clean that filter or use the booster.   

Thanks for the education.  I am trying to learn as much as I can about how these machines work and how to make them last.  The internet puts information at your fingertips but not all of it is correct.  I have seen videos where only the outer foam filter is oiled and an Outerwear is slipped over it.  Uni's video shows oiling inner and outer filter.  Somewhere I read not to use Outwear as the oil migrates to it and plugs it up.

[2015 Z Force 800 53/Trail EPS]

You must oil..or rather "treat"..as when it drys-down is more of a sticky resin, both inner and outer stages of the filter and it must be worked-through so that all the cell surfaces are coated. Otherwise it's not a filter and particles can get through. Using "Outerwears" prefilter over a treated foam filter is a problem sometimes as even a dry Outerwears are somewhat restrictive at higher flow rates. When they get filter oil on them they tend to collect what would usually drop down into the filter cells on it's surface causing mass restriction..and the more it restricts, the more it gets sucked in against the filter...and the more oil it gets....and the more your engine is air-starved. So If you must use one, IMO, you should put in on away from the filter and have them well oversized to they won't be restrictive so much when they collect stuff.

Here is a pic of a plugged-up outerwears and how little got through to the filter. The guy that had this thought it was great.. but the fact is, the engine was being hurt from lack or starving of air.

My Polaris ATV had an outer sleeve in addition to the paper air filter.  Even without getting coated with oil, the outer sleeve was constantly getting filled / clogged.  I pretty much got into the habit of cleaning it after or before every ride. 

[2015 Z Force 800 53/Trail EPS]

Yeah those dry foam sleeves serve as prefilters. At least Polaris makes a good paper filter.