gas cap sucks - K-Bikes.com - Excellence in Motion
 
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post #1 of 8 (permalink) Old Oct 12th, 2010, 5:25 pm Thread Starter
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gas cap sucks

Ocelot's gas cap sucks. Ride a few miles, crack her cap, and there's always a sucking sound. I'm thinking there's a vent that's got to be clogged somewhere. I see a vent tube coming back under the starboard aft corner of her tank, with what might be a check valve of some sort in it. This MAY be part number 19 at http://realoem.com/bmw/showparts.do?...28&hg=16&fg=05 simply named "valve"; but the drawing is far from clear. 1990 K75C. BTW.

Is this something that can be eliminated? What's it doing?

Unmitigated risk aversion is the new Puritanism, complete with witch hunts, funny outfits, and solemn preachers thundering doom. The name of God is changed to Safety; the name of Satan is changed to Lawyer; but the object remains the same: to suck all the life out of life and make you live on the husk.

Last edited by Ocelot; Oct 12th, 2010 at 5:53 pm.
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post #2 of 8 (permalink) Old Oct 12th, 2010, 6:01 pm
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does your performance suffer if you ride very far between openings of the gas cap?

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post #3 of 8 (permalink) Old Oct 12th, 2010, 8:19 pm Thread Starter
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cap sucks

Dunno. Just got Ocelot on the road last week. The PO had parked her ten years. I have been running my eight mile commute and twelve miles to the gym and that's about it. Brand new fuel pump.

Unmitigated risk aversion is the new Puritanism, complete with witch hunts, funny outfits, and solemn preachers thundering doom. The name of God is changed to Safety; the name of Satan is changed to Lawyer; but the object remains the same: to suck all the life out of life and make you live on the husk.
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post #4 of 8 (permalink) Old Oct 12th, 2010, 8:45 pm
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Yes it sould be vented, can't help you with how those are vented however,I think they had a few changes over the years. You don't want to burn that new fuel pump from lack of venting so open the cap once in a while until you figure it out.

What's with that starboard aft thing.....does that come naturally to you just like it does for me?

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post #5 of 8 (permalink) Old Oct 13th, 2010, 7:04 pm
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Mine does that too. But I didn't think anything of it because I had read in the owner's manual that it is normal.
Page 14 under Adding Fuel it says: "Warning, turn your head from fuel cap when opening. Fuel tank operates under a low pressure".
I'm thinking low pressure would cause this sucking sound when we open it...
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post #6 of 8 (permalink) Old Oct 13th, 2010, 7:29 pm Thread Starter
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blows too

No shit Wayne. Wo. That means it not only sucks, it blows. I'll have to review to manual for that one.

H96669 one upon a time, so long ago it was in a different life, I built a 52' schooner and singlehanded the beautiful thing 28,000 nautcal miles around the Pacific. Hence port and starboard. Most jargons are pretty useless. But when you see a guy facing you talking about right or left, that's when you catch the beauty of port and starboard.

Unmitigated risk aversion is the new Puritanism, complete with witch hunts, funny outfits, and solemn preachers thundering doom. The name of God is changed to Safety; the name of Satan is changed to Lawyer; but the object remains the same: to suck all the life out of life and make you live on the husk.
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post #7 of 8 (permalink) Old Oct 14th, 2010, 11:06 pm
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The check valve you found is part of the evaporative emmissions system, where the gas tank is vented into the crankcase. It should be removed and the vent run to atmosphere. There is what called an "air accumulator" available which clips to the frame. This has one hose connected to it's bottom and makes tank R&R much easier.
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post #8 of 8 (permalink) Old Oct 15th, 2010, 7:04 am Thread Starter
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goes aft

Does not go to the crank case. Goes aft where all hoses go to air. Perhaps the PO did a mod here. Going camping now. Next time I get a chance, I will remove the valve and see if it's just stuck.

Unmitigated risk aversion is the new Puritanism, complete with witch hunts, funny outfits, and solemn preachers thundering doom. The name of God is changed to Safety; the name of Satan is changed to Lawyer; but the object remains the same: to suck all the life out of life and make you live on the husk.
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