1994 K75 gas tank vents

[heejrbmw]

I had my K75 gas tank sitting to the side while I gained access to the relays. I noted that the two hoses attached to the rear end of the gas tank were brittle and broken off. I traced one to the foot peg area on the right side and the other seemed to go near the right side then turned to the left side. I did not finish tracing where it went before it was too late to see if it was attached to anything. It appears that it was not attached to anything, because the hose end was dirty and did not have the appearance of having been attached to anything. It may have gone to the left footpeg area. I searched the forum and found the following:

"It is not uncommon to take the vent hose that runs from the tank to the crankcase and disconnect it from the crankcase end and then run it to the right side by the centerstand. The thinking is that any fuel slosh caused by overfilling or any fumes caused by expansion will not find their way into the crankcase thereby compromising the oil. Usually these fumes gas off after the oil has been hot for a period of time. If you do alot of short trips (to the corner store, a close by friends house, etc,) it is thought that instead of gassing off, it builds up.

The two tank hoses (vent and filler overflow can be T'ed together if they go to the area of the right footpe(not left, there is a big chrome hot thing there!) But don't allow the filler overflow to go to the crankcase. If you overfill it , it will put raw gas into your oil.

You said that the hoses "were disconnected from THE FUEL TANK". On later K75 there was a cup underneath the tank vents that would catch anything that came out of the vent tubes and then drain through a hose, but I gather yours does not have this. If you don't have the cup, a hose should be attatched to each of the two tubes and then routed to the right footpeg area."

Lee Fulton


I found a follow up from PGlaves as follows:

"The little plastic funnel that clips to the frame under the tank is called an "air accumulator" and the part # is: 16 13 2 307 467. It positions under the two stub pipes on the tank.

The vent hose running from the tank to the crankcase was disconnected because it was one of those stupid ideas that didn't work out. Fill the tank, and park in the Sun on a warm day, and you were almost guaranteed to dump raw fuel into the crankcase - thus diluting the oil and trashing the bearings. My dealer disconnected this hose and installed the air accumulator (funnel) on my K75 back in '86 at the 600 miles service, 3 days after I bought the bike."
__________________
Paul Glaves - "Big Bend", Texas U.S.A


I believe that what I'm reading above indicates that I should replace the two brittle hoses and run both to the right footpeg area or replace with a single hose coupled with a tee. Can anyone confirm? If the line I did not trace all the way down was connected to anything, where should I look to see if I need to plug a line or crankcase?

Thanks for the help in advance!!

Ed

 

[pglaves]

Yes. One is a vent for fumes in the tank. The other is the drain for the fill overflow area at the cap. Both can be routed down to atmosphere.

The little funnel works. A "Y" fitting can work. A "T" is hard to fit.

Or run two new lines down to the footpeg area.

 

[roncooper]

If I run the accumulator, I smell gas on a hot day. As a result, I run a tube from the tank vent(front tube) to the right footpeg and let the other tube drip.
Only water from the gas cap area will drip from this one.

 

[heejrbmw]

Thanks to both of you for your responses! Since my bike does not have the funnel, I'll run new lines. Anyone know if a 1994 should have had the funnel?

 

[98lee]

Just buy one and put it in:

16132307467 AIR ACCUMULATOR $2.15



There is a metal nipple sticking up from the top of the engine block just below the fan. This should be capped. Otherwise you will have a vacuum leak.

 

[heejrbmw]

Thanks Lee. I found the metal nipple and it is capped.

 

[ghyber]

93 K75S FUEL TANK "Protuberances"

In anticipation of cable replacements, I have removed "some" parts from my K75S including the fuel tank. From reading this thread, I now have the answer as to the reason for three of the four small tubes protruding from under and the lefthand side of my tank: lefthand side forward is a vent and it is still connected to the crankcase (I removed the air filter - not an easy task getting the electrical connection off in the top section of the air filter case).

Three inches back from this vent line is the line which appears to feed fuel to the injection system. Is that right? If so, why is there no fuel coming out of this tube when there is fuel in my tank? I understand it is a pressure system, but nonetheless, there should be some fuel (tank has 60 miles worth of fuel left).

Underneath tank, there are two vents positioned directly over a small plastic cup collector leading to a tube.

Why are there two overflows instead of one?

ghyber

 

[98lee]

In anticipation of cable replacements, I have removed "some" parts from my K75S including the fuel tank. From reading this thread, I now have the answer as to the reason for three of the four small tubes protruding from under and the lefthand side of my tank: lefthand side forward is a vent and it is still connected to the crankcase (I removed the air filter - not an easy task getting the electrical connection off in the top section of the air filter case).

Three inches back from this vent line is the line which appears to feed fuel to the injection system. Is that right? If so, why is there no fuel coming out of this tube when there is fuel in my tank? I understand it is a pressure system, but nonetheless, there should be some fuel (tank has 60 miles worth of fuel left).

Underneath tank, there are two vents positioned directly over a small plastic cup collector leading to a tube.

Why are there two overflows instead of one?

ghyber

The left hand side forward is not a vent and it is not connected to the crankcase.
It is the return line from the fuel pressure regulator.

The line behind that is the output from the fuel pump which loops high up inside the tank before exiting. That's why no fuel coming out.


The front vent near the right rear of the tank is the tank air vent. It originally connected to a 3/16" x 1" nipple at the top front of the block directly below the fan motor. This nipple needs to be capped. MAKE SURE IT IS!

The rear vent is the filler cap rain drain. When you open the cap, look at the 9o'clock position of the filler opening. There is a hole. This drains accumulated water away from the filler.

The cup should have a hose connected to the rear of it that drains behind the right peg plate. THIS HOSE MUST BE THERE or raw fuel could drip on the hot engine (Pooof!)

 

[ghyber]

93 K75S Fuel Reservoir

Lee, your knowledge of the K-bikes is very accurate, thanks for correction above.

You are right on about the fuel pressure regulator. I took the air cleaner housing apart late last night and posted today without even going back to check.

Now I understand why fuel doesn't leak out by gravity since we have the equivalent of a plumber's trap inside our tank piping.

Unfortunately, I did not locate the nipple at the top front of the block directly below the fan motor. Here is a picture (my bike is a mess I know, I often get caught riding in rain) of the fuel pressure regulator. Maybe you could point my in the right direction so that I can verify that it is capped. I can take a pix of the front engine block too, if required.

So I guess I don't really need to cap the lines, is a return line and the other isn't going to leak as long as no one causes the fuel to slosh, right?

Quick disconnect valves appear to be moot at this point.

 

[98lee]

Someone neglected to replace the insulation on the underside of the fuel tank when they repainted it.

I'll go out and get a picture of that tube that needs to be capped.

 

[ghyber]

Original Paint

Lee, I am under the impression that is the original paint job. There is some dirt which I am ashamed to say I neglected to wash off before taking the pics.

I have read about riders on this Forum that have had issues on very hot riding days with the fuel heating up. Is it possible that the Canadian bikes are imported without the heat shield or insulating material? I don't know at all, but the bike paint certainly looks original.

Maybe some Canadian riders can chime in and confirm if they have insulating material under their tanks. I will ask a local rider from my area in the meantime.

 

[98lee]

The nipple that needs capping is shown at the tip of the pencil. In the picture it has a 1" tall rubber vacuum cap on it. You must remove the intake snorkel to see it.

 

[ted]

Lee you're going to have to update your sig with "And one Dakar Yellow"

I still regret taking a pass on that low mile Dakar Yellow '94 with the complete set of spare panels, new in bag solo seat, new in bag liners, and of course two new in bag bulb kits Apparently sold to a woman from Nova Scotia who bought it sight unseen, flew down and rode it back.

 

[ghyber]

Capped Off Crankcase!

Thanks for that picture Lee, it helped a lot.

It appears that someone has capped off that opening on my K75S. I took a picture and the tip of the screwdriver appears to be where your pencil tip was pointing at; there's nothing else there anyway. The camera shows it better than I had expected. Even with a portable lamp, I could not see that with as much detail.

I also cleaned the underneath of the tank and it certainly looks like original paint to me. The bike only had 64,000 km when I purchased it. Then again, there's always a possibility that it could have been repainted. If it has, that's all right. I am just wondering if I should purchase and install those three insulation sections. Up here, I can probably count on one hand the number of weeks of greater than 80F temperature and the number of days of greater than 90F on one hand. The second pix is a little out of focus, too close.

 

[ghyber]

1993 K75S ECE Model

I went to the Max BMW website and investigated for the part numbers for the European model, if that is what ECE stands for, and they don't list the insulating material.

http://www.maxbmwmotorcycles.com/fiche/DiagramsByPartNumber.aspx?parts=16 13 2 307 467

http://www.maxbmwmotorcycles.com/fi...6&Diagram=16_0808&menu=&parts=16+13+2+307+467

 

[98lee]

Not mine. It's a buddy's (Quickdraw) that I just put a clutch and tranny input shaft in.

It had the dreaded misaligned spline syndrome. Second clutch and tranny splines in 66,000 miles. First one was changed at the dealer at 33,000 miles. I believe I found the root cause (and is wasn't the intermediate housing). Story to follow after I discuss it with Don.


It was just the easiest to get to for the picture. It's going home Saturday.

Currently my shop looks like this:

My four Marakesh Red K75Ss, Quickdraw's Dakar Yellow K75S, and a Koenigs Blue '87 K75C with rear disc brake that I picked up. Next week another '88 K75S will be showing up that needs reviving before being reunited with its owner.

 

[ghyber]

Topasrotviolet

Not mine. It's a buddy's (Quickdraw) that I just put a clutch and tranny input shaft in.

It had the dreaded misaligned spline syndrome. Second clutch and tranny splines in 66,000 miles. First one was changed at the dealer at 33,000 miles. I believe I found the root cause (and is wasn't the intermediate housing). Story to follow after I discuss it with Don.


It was just the easiest to get to for the picture. It's going home Saturday.

Currently my shop looks like this:

My four Marakesh Red K75Ss, Quickdraw's Dakar Yellow K75S, and a Koenigs Blue '87 K75C with rear disc brake that I picked up. Next week another '88 K75S will be showing up that needs reviving before being reunited with its owner.

I think you need to add a Topasrotviolet (colour code 246) 91 K75S with 15,000 km, one owner original owner bike to your collection. It's not mine though. It's a K-bike I saw advertised around here last autumn. Never driven in the rain!