K11 Owners Group

joeangi · Posted: Sun Feb 15, 2009 10:47 pm Post subject: Vacuum Hose??

Hi everyone...I found an errant vacuum hose, and I don't know where it goes. It runs from a small "F" in the engine block, just behind the radiator. One leg of the F goes to the air box, the other a small 1/8 size line runs up to under the tank along the right side frame rail...but it has a plug in it?? It appears to be an original hose as it is all cracked.

Why run it all the way up to under the tank, just to plug it? Is it a vacuum test hose?

Thanks,
Joe

Scott_Anderson · Posted: Sun Feb 15, 2009 11:48 pm Post subject:

It most likely went to the fuel tank vent line for vapor recovery. Now there should be a collector cup under the right rear of the fuel tank that sits below 2 hose nipples. This collector is then hosed/drains down the right side behind the footpeg plate by the rear brake pedal.

1 is for fuel overfill/overflow/vapors/vent. The other is piped up to the rain drain around the fuel cap.
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1995 K1100LT 0302044
2017 FLHTK Ultra Limited
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"One who does not ask questions is ashamed to learn" Danish proverb
1997 K1100LT 0302488(R.I.P.)
1997 R1100RT ZC62149(sold)

joeangi · Posted: Mon Feb 16, 2009 8:30 am Post subject:

Dear Scott,

Thanks for the reply. I have the collector cup, and that is attached to nothing. I figured that that was the rain drain, and was going to drain that down to the footpeg. Vapor recovery makes sense, but if it also is for overflow...I really don't want raw fuel into the crankcase.

On my old K the two hoses go straight from tank to peg, and they get connected under the tank.

Do I now only hook up one line under the tank, as the rain drain goes into the collector cup?

Thanks,
Joe

Scott_Anderson · Posted: Mon Feb 16, 2009 8:58 am Post subject:

Phil Marvin · Posted: Mon Feb 16, 2009 2:15 pm Post subject:

Hi, Joe,
Your bike most likely has had a "flapperectomy". As it came from the factory, there was a flapper just under the fill cap. This was held onto the fill cap by 3 screws (accessible after removing the cap from the tank). The flapper was removed and saved for when the bike went for inspection or, most likely, discarded. The 2 nipples under the tank had hoses attached. One went behind the brake pedal and vented to atmosphere. The other had a 1-way valve in it and attached to a fitting on top of the engine just behind the radiator. This vented gas fumes (and maybe raw gas) into the crankcase where, via the breather hose, it went into the intake and was consumed.

Many of us did not like the idea of venting gas into the crankcase, so we removed the flapper (could put about another 1/2 gal. in the tank), removed the hoses from the under-tank nipples, plugged the hose to the crankcase, added the "air accumulator", BMW's name for the funnel which goes under the nipples, and attached the other hose to the bottom of the funnel and ran it to behind the brake pedal. Some didn't remove the flapper (less chance of fuel sloshing out the vent on hard acceleration with a full tank), but I wanted the extra capacity.

I hope the above explains what you probably have discovered.

Ride Safe,
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Ride Safe,
Phil Marvin in El Paso, TX
'94 K75A/3
'95 K75RTP

joeangi · Posted: Mon Feb 16, 2009 3:31 pm Post subject:

Thanks guys...The flapper is still on the gas cap (checked). I agree with just capping it down at the crankcase. No sense running a capped hose up to under the tank.

Let me get this straight...I don't attach any hoses to the bottom of the tank when I put it on??? That is great, just let those two nipples go into the funnel, and then hose off the funnel to the rear peg?

Thanks,
Joe

Saltcreek · Posted: Mon Feb 16, 2009 6:24 pm Post subject:

OK I've read others talk about flapperectomies and I don't get it. I can't see what harm it does and can see some potential good and no way do I see it making room for 1/2 gallon of gas. What am I missing?
_________________
Jim

1994 K1100LT Mystic Red, bfd, 37000 miles, sold Sad

2009 Wilderness Systems Zephyr 155 ST
2002 Litespeed titanium

joeangi · Posted: Mon Feb 16, 2009 6:28 pm Post subject:

I did it on my K100. Basically, you are making the fuel neck a little taller, so the fuel pump will allow you to put more in the tank. The downside, is you are venting my harmful fumes into the atmosphere, that and sloshing a little when full....I put it back on, I did not like getting some fuel onto the tank.
Joe

Off the grid · Posted: Mon Feb 16, 2009 7:29 pm Post subject:

Did the flapperectomy a while back, pretty much a no-brainer.

Got 20-40 more miles out of a full tank with it.
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Phil Marvin · Posted: Tue Feb 17, 2009 11:27 pm Post subject:

Saltcreek · Posted: Wed Feb 18, 2009 8:31 am Post subject:

I stand corrected. Presumably I'll find a flapperectomy thread if I decide to do it.

But if it's such a good idea, how come my spell checker wants me to replace it with hysterectomy? Confused

_________________
Jim

1994 K1100LT Mystic Red, bfd, 37000 miles, sold Sad

2009 Wilderness Systems Zephyr 155 ST
2002 Litespeed titanium