K11 Owners Group

[tonup]

While travelling cross country a few weeks ago I noticed a phenomenon on my 96K1100RS SE and I’d like to submit this to the list to better understand what is going on.

The bike is a low mile (now 15K) example that I bought used from guy in Virginia (had 11.4K on it when purchased). The only services done were the 6 and 12. To my knowledge the tank has never even been off the bike.

The phenomenon is as follows: when arriving in Chadron Nebraska (I live in Charleston SC) I noticed some brown stuff on the rear drive. I wiped it up and it had stained the rear drive. Damn. I thought it was oil. It never happened again until a few days later when in Kansas City I noticed it again- I had been looking for it each fill up thereafter. That evening I figured out what it was. IT was fuel driplets. They were condensating at the bottom of the overflow valve and then falling off the condensate tube and then landing on the rear drive- believe it or not. I wiped the rear drive up again and it happened only one more time en route back to Charleston SC (so around three to four tanks worth (after noticed) over probably 90 gallons or so purchased via the whole trip). Once I arrived in Charleston- at home- and a place much hotter than anywhere else I’d been I could see it happening…the fumes were coming out of the breather valve and then a drop was condensating on the bottom. Obviously while riding those droplets were coming off the breather hose and landing on the lower half of the rear drive- my suspicion was confirmed- I had also just run the bike at the higher speed- 90mph- to get home. How weird I thought. Am I the only unlucky SOB who this has happened to? If not- and I the only unlucky guy this has happened to whose breather hose happened to be at the correct height as to allow it to drip back on the rear drive and stain.

Here is what I know and some possible pertinent facts:

I did ‘overfill’ the tank twice and only twice did some fuel get into the overflow valve to my knowledge- done while ‘topping up’ so as to get as many miles outta her as possible.

On at least two of the tanks where I noticed the phenom occur I KNOW I had not overfilled the tank.

I know the phenom is occurring as above and as I witnessed it.

The flapper valve is removed from the tank (as I read and was told to do).

There was definitely alchohol(ethanol) in the gas when it was happening.

Twice when pulling up to a station I heard the fuel pump buzzing really loudly- it did this on two tanks in a row but stopped and never did it again and it did not seem to correlate with the driblets going to the rear drive necessarily but it could be a pertinent fact.

The fan rarely came on and the bike never ran in the red- although it was hot- could feel it.

I can seem to smell gas often when my head is down enough to be tucked behind the aeroflow shield to allow wind noise to disappear.

The tank- to my knowledge has never been removed and therefore I doubt there are any pinched breather hoses or whatever.

I always fill up on the center stand (one friend with a K says he never does this for what it’s worth).

Question is: What is causing this? Is it the alcohol in gas evaporating off due to the heat in the tank then re-condensing on the end of the breather tube and I’m just unlucky in that mine drips back on to the final drive? Will it continue to happen even with not alchohol fuels- like I get where I live? Has anyone else had this happen or run into this? I am assuming at this point that this phenom will continue to occur and that my only option may be to reroute the vent hose and/or extend it so that the drips don’t fly back onto the rear drive.

Thanks for you help in advance!!!

Anyone who wants to email me directly may do so at beck.built@hotmail.com. I could also send pics if anyone is interested.


NTB

Charleston SC

[tonup]

please also advise if you know a way to get fuel or other stains off the rear drive silver paint. I tried polishing with meuquirs and using a solvent to clean it. neither worked. I guess i'm stuck repaintig with Wurth Silver and the reclearcoating? or leaving it be and riding happy?

Regards
NTB

[jpberens1994K1100RS]

I had a 94RS, now a 93RS after the 94 got wiped out.
Never noticed this happening, fill up pretty full all the time, yes the fuel pump whines real loud if you get much under a half gallon. My over flow hose hangs below the swing arm by at least 4". I tie wrapped it loosely to another point on the swing arm to stop it from flying around.
The stock silver rims are painted with some kinda chit paint, dirt clings & they stain easy & they are hard to polish. My 93 is Graphite in color code 670 I think, and I am considering painting the rims gloss black this winter when I stop riding it for a few months.
Can't think of much to get the stains out though, eventually you will polish rigth through the paint.
_________________
1993 K1100RS that I'd rather be riding FAST!
2014 Moto Guzzi Norge

[m.cycle]

same thing happened to me a few years ago with my 96 k1100rs on a trip to fla. spent quite a while trying to figure it out and the following is my understanding of the history/folklore of the fuel tank vent. supposedly, the original design of the vent tube (or whatever you want to call it) went directly to the crankcase. somewhere between manufacture and sale the tube was rerouted so any fuel/vapor wouldn't go directly to the crankcase but to atmosphere. when i noticed fuel dripping from my vent it was in super hot weather and heavy traffic. long story short i ended up having a "cup" mounted under my tank with the vents going to it, rather than the hose running down by the swingarm. that was probably 7 or 8 years ago and haven't had an issue since. i don't remember my mileage then, maybe 20-30 thousand, now i'm around 84 thousand. my disclaimer is i'm not very bright and this might have been a story invented by the dealer so i'd go away, but that's my story and i'm sticking to it.

[tonup]

Thanks very much...I was hoping to find someone else who it had happened to or who had noticed it (but not stained their parts like me). I've read the clymer and bmw factory manual and there is definitely variation amongst the models with this (and the feedback i am getting based on peoples bikes) so you having a 96 as well is very pertinent and you being in a hot place like me is also very pertinent..i'm going to begin some disassemby and inspection and i'll let you know what you find.

[DetroitDan]

No solution, but an affirmation:

The fuel in mine boils, when stuck in traffic on hot days; or really hauling on hot days with a full-tank.

The bottom of my final drive is stained, too.

I have tried several things, but not found anything to remove the stain.

Last week we did a couple laps of a "cruise" night. Even with a half-full tank, the hose was steadily dripping fuel.

I haven't figured out a reasonable solution, yet.
_________________
1973 CB350F / 1977 R100/7 / 1991 DR650S / 1995 K1100RS

"No man in the wrong can stand up against a fellow that’s in the right and keeps on a-comin’” Capt. Bill McDonald (1852-1918)

[Jim]

There are probably a couple of things you need to do. Install an "air accumulator" - the cup that replaces the line to engine and the rain vent.

There is a nipple on the "shed biscuit" that squirts the return fuel (unused by the injectors) back into the tank. When it's really hot, the return fuel can get sprayed back into the tank in such a way that the fuel gets into the tank vent and comes out the hose. When this happened to me, I figured fuel was getting out through the cap and coming out the rain vent.

The fix (at least for mine) was to put a length of gas line on the nipple - has to be long enough for the end of the hose to lay down in the bottom of the tank. The return fuel then goes to the bottom of the tank and into the fuel that's already in the tank - that way the return fuel can't spray around in the tank and get picked up by the vent.

Make sure your gas cap is in good condition also - mine needs new gaskets.
_________________
Jim
1997 K1100LTSE 94,000 - still has gremlins!
1995 R100RT Classic 16,650 crashed - repaired!
1992 K75RTP 46,000

"We shall not all die, but we shall all be changed."

[DetroitDan]

Thanks for the idea.

It makes sense. When I pulled over, opened the cap, and cycled the pump; the fuel was spraying pretty wildly.

I'll try adding to the return line.
_________________
1973 CB350F / 1977 R100/7 / 1991 DR650S / 1995 K1100RS

"No man in the wrong can stand up against a fellow that’s in the right and keeps on a-comin’” Capt. Bill McDonald (1852-1918)

[tonup]

OK Guys,
It has taken me a while to get the time (since posting for help & input) to analyze this situation but here it is:
I took off the tank yesterday to find that the front vent nipple on the bottom of the tank had nothing on it. Nor did the rear nipple. The rear nipple doesn't matter since it goes to the top of the filler hole and it's supposed to drip into the plastic funnel cup (and then down & out the hose exiting below the drivers footpeg on the right).

Therefore the vent to the crankcase, the front nipple (front meaning toward front of bike), was unhooked and the fuel from the tank top overflow was dribbling into the black plastic funnel cup and out the vent hose- and from there onto the rear drive and thusly staining it badly. So it must have been a situation where it was leaking occasionally just based on when the fuel level was high enough. Or when some sloshed in getting it off the center stand at the station or whatever (one guy here int his post speculated that the return hose could splash fuel in such a way as to occasionally get into interior vent?) It is also possible as well that it is in a fact a heat & moisture phenom that occurs when the gas gets really hot inside the tank (which it does)- the pressure builds, fumes/gas exits and viola down into the plastic funnel and out onto the rear drive! And it accounts as to why I always smell gas when my nose is one inch below my aeroflow and out of the stream of air..or when sitting at intersections.

NOW- the hose to the crankcase was unhooked and obviously intentionally 'cut off' via a metal hinge pin of correct diameter stuck down into it. It was obviously done this way on purpose. I doubt someone just plugged it via tank removal and 'forgot' to put it on because if you were taking the tank off- you wouldn't really need to plug this thing up in the first place while working on bike cause there's no reason to that I can see. It was done by the guys at Hammersley in VA (the guy that owned it before me did not work on it)....where it was serviced- so it was done at the dealers I assume. Another guy on this list posting below said his was this way (and he experienced the fuel dribbling back and out that I did) and he was told that they did it somewhere between germany and delivering the bike at his dealer. His dealer told him it they were cutting this part out on purpose?

So the question is: hook the tank back up with the vent going to the crankcase via the little 'funnel' or check valve as originally designed....and that's the way it should be...period...and its ok for fumes/small driblets of fuel occasionally to get into the crankcase via the vent line check valve system...or

Leave the crankcase vent hose off & plugged up as it is and simply let the system run as it is (except making a countermeasure to the fuel driblets such as guy above did or a longer hose to the ground). Was this a BMW bulletin to do this? Does anyone know?

Your help is greatly appreciated!

[Mystic Red]

I for one didn't want gas going into the crankcase so plugged the hose and installed a funnel (air accumulator). Both nipples bleed into it and I have no problem with gas staining the final drive. Maybe a longer hose is the ticket.
_________________
Scott Hespelt, '94 K11LT
K11 OG #466

[WVMSFKRS]

I just got back from a 2183 mile 4 day trip to Duluth and had the same problems. I noticed the gas smell, the whining of the fuel pump, mine was even cutting out when I rolled on the throttle. I thought it might be a vapor lock, once I got fuel it never did it again. Luckily it was the last 300 miles. Could some send a picture of these nipples or will it be obvious when I look under the tank.

This is a great forum, and thanks to everyone for their help!
_________________
IBA#42211
MSF Rider Coach
Riders Edge Instructor
'09 K1200LT
'07 K1200GT Traded
'96 K1100 RS SE *SOLD*
'05 HD Ultra 82,000+ miles
'04 URAL *SOLD*

[Mystic Red]

They are on the right side of the tank. They'll be obvious.
_________________
Scott Hespelt, '94 K11LT
K11 OG #466

[Flying Duck]

Put a longer hose on it and use some zip ties to point it away from the paralever bar and final drive - like straight down from under the peg plate.
_________________
93 LT (x2)
94 RS
86-97 K75F(K75/100/1100 Frankenbrick)
86 K75C w/paralever, hi perf cams,TURBO!
91 & 92 K75Ss
91 K1
86 custom K100
14 WR250R
IBA #17739 (SS1K, BBG, 50CC)
Buy parts HERE

[Moondog]

My crankcase vent was plugged up since day one that I have owned it from 82K. I talked to many techs and have said that hose is not necessary so a bolt is stuffed in the end and ty-wrapped. I haven't had any issues with it.
_________________
"Badges? We don't need no stinking badges"!

I like the social aspect of riding. Rally's, socializing, drinking beer, fartin' and carrying on.

2004 R1150RS
1996 K1100RS (moved on to new home)

[lostboy]

There was indeed a service bulletin regarding the tank venting into the crankcase. This was BMWs solution to California's "shed test", which restricts evaporative emmisions. All dealerships outside of CA were requested and paid to remove the shed sytems from all BMWs. The air accumultator was the suggested method of collecting fluids from both overflow and vent tubes.

Later, due to complaints about whining fuel pumps at lower fuel levels, a warranty fix was to install a piece of submersible hose on the internal fuel return pipe and direct the returned fuel over the pump. This also gets a few more miles out of a tankfull.

A less than perfectly routed vent line allows the Bernoulli principle to take effect; air flowing over the end of the line actually canpull fuel out of the tank when it is near full. A solutiom to this is to cut the end of the hose at an angle with the short side of the angle facing rearward.

[lostboy]

There was indeed a service bulletin regarding the tank venting into the crankcase. This was BMWs solution to California's "shed test", which restricts evaporative emmisions. All dealerships outside of CA were requested and paid to remove the shed sytems from all BMWs. The air accumultator was the suggested method of collecting fluids from both overflow and vent tubes.

Later, due to complaints about whining fuel pumps at lower fuel levels, a warranty fix was to install a piece of submersible hose on the internal fuel return pipe and direct the returned fuel over the pump. This also gets a few more miles out of a tankfull.

A less than perfectly routed vent line allows the Bernoulli principle to take effect; air flowing over the end of the line actually canpull fuel out of the tank when it is near full. A solutiom to this is to cut the end of the hose at an angle with the short side of the angle facing rearward.