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Question about XX engine


Scooter9495

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Hello i am new here and wanted to say hello,i also have a question-is it normal when you remove the oil fill plug while the bike is running to have a flow of air blowing out? i was pretty sure while running there should be vacuum in the crankcase.the bike is a 2002 with 5400 miles.

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:icon_eek:

The oil should blow out like its ass is on fire. The crank sloshing around the oil should also make air blow out as well.

Now answer me a question.. What does oil do in an engine?

What does an engine do when there is no more oil in running engine?

Please don't do that anymore.. :icon_wink:

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There should be a crankcase vent tied into the airbox.

Thanks for responding,i understand the vent tube to air cleaner box but im worried i am getting "blow by" by the amount of air being put out from the filler plug.

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There should be a crankcase vent tied into the airbox.

Thanks for responding,i understand the vent tube to air cleaner box but im worried i am getting "blow by" by the amount of air being put out from the filler plug.

If you want to keep your engine alive, never pull the oil plug while the bike is running. If you are concerned about blowby ( you should not be ) do a leakdown test and then you'll know without destroying your engine.

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You're fine just enjoy the ride. If you had blow-by your airbox would be full of oil. These motors are good for well over 100,000 miles, so unless someone did something dreadfully stupid you are good to go.

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He said oil fill plug, guys, not oil drain plug. :icon_wink:

:icon_doh:

You don't fill your engine up with oil from the drain plug? :icon_think: I figure that since its already off I might as well fill it back up that way also :icon_lol:

But you gotta be quick, I watched Karate Kid 6 dozen times before I mastered it..

Sorry I misread your question.. :icon_redface: Yes it should be blowing air out...

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He said oil fill plug, guys, not oil drain plug. :icon_wink:

:icon_doh:

You don't fill your engine up with oil from the drain plug? :icon_think: I figure that since its already off I might as well fill it back up that way also :icon_lol:

But you gotta be quick, I watched Karate Kid 6 dozen times before I mastered it..

Sorry I misread your question.. :icon_redface: Yes it should be blowing air out...

Ok, thanks alot everyone i just wanted to make sure.

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the bike is different from car, fill car from rocker there should be no puffing from filler, if there is you have possible ring damage allowing compression to leak down to sump, bike is different, the air you see coming out is a product of the movement of oil round the engine under great pressure from the oil pump, you will alway get this, you also have the pistons on their way down stroke this will also cause pressure

so don't worry

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Has nothing to do with the pressurized oil running around inside the engine. That is all contained within oil passages until it bleeds out the sides of the bearing surfaces and returns to the sump, at which time it is free oil.

It has everything to do with the fact that pistons pump air and from both sides! (who would have thought). In theory, since two pistons are going up and two are moving down almost all the time within the engine crankcase volume should remain the same and crankcase pressure should remain neutral. In practice, the air communication between the cylinders is not that good and the crankcase can become pressurized at even fairly low RPM.

For quite some time now, drag racers have been fitting vacuum pumps to the crankcases of their engines as these pumping losses are significant. There is about 10 net HP to be gained at the expense of a little weight and complexity. The NASCAR boys do it too, just in a different way, with their dry sump systems. They run as many as 3 or 4 stages of scavenge pump on their dry sump systems.

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