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Exhaust from timing hole

Old 09-20-2010, 06:14 PM
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Exhaust from timing hole

Well.....that's my question. I get a stream of "air" out of my timing bolt hole and flywheel bolt cover while the bike is running. Is this normal? It could be just air blown by the flywheel.......but it seems like a lot. I'm concerned about the o-ring between the cylinder head and valve cover that seals the exhaust tube for the PAIR system. Any ideas out there?
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Old 09-20-2010, 07:29 PM
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Very unlike an I4 where they cancel each other out, the pistons move up and down almost together on a V2. This causes a lot of air movement in the crank case. I know a lot of air move through the oil filler if you remove the plug, a very quick pulsing back and forth. Probably the same phenomena your describing. It's normal.
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Old 09-20-2010, 07:52 PM
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It's pretty much normal. These motors have pretty big pistons and they do pump a lot of air. So that and the 270-450-270 firing order on this motor would make it pulse.

Now if it's a "steady" stream it's probably the flywheel, though it is kind of hard to guess how much "a stream of air" really is. Can you put your hand over the hole and block the stream? If so don't worry about it.

If it blows your finger off the hole, have someone that know what they are doing look at it.
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Old 09-20-2010, 09:20 PM
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My wife left her oil filler cap off on her '86 Toyota ExtraCab 4x4 about 15 years ago, after adding oil at the gas station near home. She drove 30 miles to work the next day, and most of the way home, before oil started streaming up the windshield. The oil cap was still sitting on the valve cover.

She wiped under the hood as best she could with towels before I got home. I took it to school the next day and spent 20 minutes with the pressure washer and another 20 with an air nozzle. The plug wires failed 2 weeks later.

A LOT of air moves inside the crankcase, both from piston movement and blow-by.

I saw the same thing a month later on a school employee's Honda Civic. Jiffy Lube did that one...and they got to clean it up.

Last edited by VTRsurfer; 09-20-2010 at 09:24 PM.
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Old 09-21-2010, 04:53 PM
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Thanks guys. I didn't think about the pistons. I forgot the the piston bottoms are open to the crankcase. Duh!
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