MOTOBRICK.COM
TECHNICAL MOTOBRICK WRENCHING In Remembrance of Inge K. => The Motobrick Workshop => Topic started by: beemrdon on June 16, 2016, 11:54:55 PM
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I had my gas tank off this morning and accidentally broke the inline one-way check valve which vents gas fumes to the engine. OK, no big deal. So I got on the computer and went to Max parts look-up... and discovered that the $7.00 valve was discontinued in 2011. After some thought and research I learned that the line going to the engine could be plugged. I used a bolt pushed into the hose that goes to the motor.
What I didn't expect is how great the bike now runs.
Every K owner should plug that hose!
The pics show the bottom of the gas tank, the broken valve in my hand, the hose coming up from the bottom of the engine and the two pipes at the bottom of the gas tank (not necessarily in that order).
The first pipe is for the valve and the rear pipe is for water drainage so that water doesn't get into the gas.
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I put the bolt at the end of the hose that goes to the engine after cutting off the check-valve piece which was stuck in the end...visible in the pic.
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My main point in posting this is to give other folks a heads up who still have the California anti-pollution valve hooked up.... this hose should be plugged (from my experience). None of the posts that I read mention that the bike may actually run better.
It seems to make my already awesome running K1100 motor run even better.
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greetings beemrdon...
thank you for your positive contributions at the world famous motobrick.com...
j o
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No Problemo. :bmwsmile
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is this a vacuum thing? can anyone else confirm, deny, or shed some more light on this ?
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I believe it is. It was an afterthought, BMW had to try to make the bikes "cleaner" for emissions requirements.. I don't know if all K bikes have them or just later K's.
I have read that BMW sent out a memo a few years ago telling their mechanics to plug the engine inlet. They stopped selling the one way valve in 2011. So they didn't think it was too important.
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It makes sense. I'm wondering if the vacuum correction is coming from the engine side or the tank side.
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What do you mean by "correction"?
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What do you mean by "correction"?
well if the bike is running better by plugging up 1 or 2 of these holes being the overflow / pressure release from the tank & the related hole going to the engine crank case then what we're assuming is that by having this thing routed the oem way causes a vacuum leak which is throwing the whole system outta wack. it seems like this was a quick and easy fix for bmw to quickly meet emissions standards at the cost of performance.
so im just curious, if this is a vacuum leak, does it stem from the tank or from the crankcase. being that they are both under pressure and need to be air tight.
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When I bought my K75RT new in 1990 the dealer removed that hose and valve and plugged the tube on the engine block with on of the little caps that are on the throttle bodies. I never even thought about it since but that valve is in a ziplock bag in the bike's tail as I keep everything.
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It makes sense. I'm wondering if the vacuum correction is coming from the engine side or the tank side.
It's not vacuum, it's the reverse of vacuum: When pressure builds in the tank (like from cool gasoline or gasoline vapors on a warm day), the vapors are *pushed* out through the valve into the crankcase, instead of being released directly into the atmosphere. I guess theoretically the gas vapors will wind up traveling through the crankcase vent Z-pipe into the combustion chambers and be burned. The one-way valve prevents crankcase gasses from being pushed into the fuel tank. It may or may not prevent air pollution, but it definitely doesn't help your K bike run any better.
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but it definitely doesn't help your K bike run any better.
Well, in that case then, billday, removal has a strong placebo effect. Who wouldn't enjoy that, and only at the cost of a bolt?
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The bolt was free! :riding:
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The bolt was free! :riding:
Placebo plus! :clap: