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Discussion Starter #1
Is it normal with a little bit of oil inside this hose conected to the air box? Also a little bit inside the "conection-part" of the air box, but the box it self had no oil in it.

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Perhaps the best answer to your question will come from others who may have looked at the inside of their intake systems and found similar conditions.

Here's my long winded take on it:
Are you certain it is oil? On other engines I've seen an oily film that appears to be oil but is in reality a mixture of carbon and fuel inside intakes of engines, not necessarily UTV engines. As far as I can determine, unless something is mechanically wrong with the engine, what appears to be oil in those engines is caused by operation at an RPM that causes fuel standoff. At some particular RPM tuning of intake and exhaust is not optimum, vacuum level is low enough that it allows some fuel air mixture in mist form to actually "flow" backwards through the carburetor or throttle body where is adheres to the surfaces of the surrounding intake side of the system as a sticky oily substance.

Although it is assumed by many that the flow through an engine is a steady stream, in reality it is not, it pulsates at a high rate with the opening and closing of valves and motion of the piston. Engines with greater valve overlap (longer duration cams) tend to be more prone to this occurring becasue the time both intake adn exhaust intake valves are open is greater and occurs during a portion of the 4 stroke cycle where the piston is moving upward on the compression stroke. During that period, when there isn't enough residual flow through the engine due to intake/exhaust tuning mismatch at that particular RPM, intake mixture can actually momentarily flow backwards and be seen as a mist outside the carburetor or throttle body if intake parts like air filters and intake ducting are removed. Most engines have short low restriction intakes and longer exhausts, which create greater restriction than the intake, which exacerbates the situation.
Of course there may be mechanical deficiencies that do cause oil to end up in that location. Bad valve guide seals, worn valve guides, worn rings, clogged engine breather, engine breather that is stuck in the open position, valve float (possibly caused by weak valve springs or over revving) to name the most common.

It's also noteworthy to mention that all engines consume some oil. Rings and valve guide seals are not 100% seals. There will always be some oil that makes it past them, even if it's unnoticeable and a minimal amount. Operation during high vacuum conditions such as long deceleration down slopes using engine braking can increase oil consumption becasue the throttle is closed and the engine is still trying to draw in air. This creates a high negative pressure in the cylinder and anyplace oil can make it's way from the crankcase past the rings or valve guides will allow oil to enter the cylinder. In cases of worn parts oil can accumulate to the extent that blue smoke will appear out of the exhaust when the throttle is opened next time. In severe cases plugs may become oil fouled. In most cases where the engine is in good condition oil consumption via this avenue is minimal but we may notice the oil is low at the next oil change or at some interval between changes. This, of course, is normal.

In general higher performance engines tend to have the greatest amount of valve overlap and produce the greatest power at high RPM. I would consider most newer motorcycle style engines that Polaris produces to be of the high performance type. 1000cc is about 61 cubic inches and power output if that engine is about 82 HP based upon the specs I read. Any time you get an engine to produce more than 1HP per cubic inch you are getting into the high performance zone, IMHO. Modern technology engines with greater than 1HP per cubic inch are not uncommon and tend to reliable so they are often not considered to be high performance, but the realities of how that horsepower is made are that cam timing is part of the equation, along with cylinder head design that allows higher compression operation without pinging or detonation, fuel injection, computerized controls that take into account air pressure and temperature, air flow, engine temperature, perhaps monitor exhaust to determine fuel mixture and more. In the end some of the design features of old style high performance engines still contribute to HP output and conditions associated with those design styles still apply.
 
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Somewhere that engine will have a PCV valve. If the crankcase vent is plumbed upstream of the air filter that could be the source of the oil. Usually the PCV valve hose is in the intake plumbing between the filter and engine though.

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With the filter and box being clean, it has to be upstream or left from manufacturing. Makes for a good seal anyway...
 

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Discussion Starter #6
For me it certenly looked like oil. Light brown and felt like oil between my fingers. Did not taste it...

The machine starts, idles and runs great as it always has, so I’m not that worried. But the thing in there that I was 100% sure was oil (95% after what pyro wrote) just dont makes sense to me. Interresting if anyone other with the ’18 1000 xp would have a look at the same place, and if they find any.
 
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