Got oil pouring into air filter and then onto exhaust after about 40miles,engine not missing or louder than normal.have been getting a gray thick liquid in small amounts from time to time in the breather hole at the bottom of air filter box help

There are three common reasons for oil on the plugs. A blown head gasket, worn valve stem oil seals and worn piston rings. The most likely reason will probably be the head gasket.
Check the coolant overflow tank for oil floating on top of the coolant. This is a sign of a blown head gasket.
For Valve stem oil seals check the following... On a Cold start you get a large thick cloud of blue coloured exhaust smoke. You also get the same smoke when going from idle to higher engine revs. Such as pulling away from a red traffic light after sitting waiting for traffic.
Does the vehicle use a lot of oil? Does it have excessively smoky exhaust gas, usually more of a grey/white colour, when driving? Has it lost power? Look in the engine air filter box. Is there oil? Worn piston rings sometimes cause 'blow back' where an oil/air vapour is forced back through the air intake into the air filter box.

Next check I'd do is Fuel correct then Spark Plug, if still then Check for a broken or miss aligned ring.
Note:
If the exhaust smoke is blue or gray: Thick blue or gray smoke is an indication of the vehicle burning oil, which means that oil is somehow leaking into your engine'scombustion chamber.
If you have wrong fuel say have 2cycle mix and put in a 4cycle you'll get fouling too.
Hope I helped
Mike

Could be bad piston rings but first check your oil in the engine and if its too full this could cause burning oil. Check your air filter and if its clogged replace it as this will do it also.

Will, let me tell you the "Old school" way to fix this.(1) Remove all of the spark plugs. (2) Disconnect the fuel lines. (3) Pour light weight oil directly into the heads.(I know, sounds weird) (4) Crank Crank Crank Crank. Until the engine turns smoothly. If the valves were stuck, this should cure it! (5) Blow the oil out by the compression of the engine cranking. (6) Pour alcalhol into the cylindars to clean the oil out of the top of the pistons.(Starting fluid also works well) (7) Again, Blow it out using the compression of the engine. (8) Put everything back together and fire it up! NOTE!!!! Any time you know you are going to store anything with an internal combustion engine, treat the engine in the same way, by pouring oil into, and onto the pistons directly. This prevents seize ups, and helps to preserve oil seals. ^^

I would suspect it is a wheel bearing issue, if it sounds similar to a baseball card in the spokes of a bicycle, stays somewhat same pitch just louder with speed that is where I would look. Does noise go away or change when making turns?

Most people consider white smoke to be oil burning in the engine. But that is not always the case. If the carburetors are pouring too much fuel into the motor that can cause white smoke to pour out of the motor. If oil or antifreeze got into the exhaust system , that could take a few miles to burn out causing white smoke. Lets assume the bike was laying on it's side for a few hours. Did you check your air filter and air box to see if they were full of oil. An overlooked air filter clogged with oil may be all that is causing this issue.

Is the white smoke steam or water? If so it is a blown head-gasket. Fix ASAP or you will ruin the engine. Or is exhaust blueish/gray or gray and smells like gas or oil. If this is the case then it could be a fuel injector, spark-plug (or no spark to plug), valve seals, piston ring/s, or clogged air filter.

check the fuel filter and the EGR valve

you have a blown head gasket you need to get it to a shop as soon as you can

White smoke usually associated with water or moisture. it doesn't take too much water to produce white smoke. check

1. cloudy oil under oil cap
2. leak through gasket from cooling jacket to combustion chamber