I'm putting my bike back together after having the fairing repainted and I'm starting w/ my fuel tank. Do I need to attach the black rubber hoses to the fuel tank as shown in the picture below?

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cant really see the pics clearly
but if its the rubber tubes running back to the swingarm
they should connect to a small bowl which just sits on the frame below the 2 outlets on the under side of the tank ......

I just edited the picture.

yep that's them ......look for a small odd shaped plastic bowl  with 2 "sit over" plastic bits that sit at near right angles to each other ...sorry don't have a pic available

Not all bikes came with the "the cup". (a.k.a. air accumulator)  My 90 K75RT had hoses on both of them.

From the Haynes manual:

The tube connects to the front of the two outlets which is the breather for the tank and as it has not got the catch cup then it should go to a charcoal canister (smog control). Mind the canister probably ended up in a dumpster long ago. The other outlet is for the drain at the fuel cap, the small hole to the left side of the filler cap, and exits down near right side the pillion footpeg.
Real OEM is a great place to get info on almost everything BMW parts and assembly wise. http://realoem.com/bmw/

Charcoal canister???.......have you been smokin' something illegal today, Rick.

Some of the US models had a charcoal canister on the vent just like many of the cars of the era.

First models that got a charcoal canister was the K 1200's.

I can't find any reference to it but I think that the Californian regulations caused them to be fitted.
I shall keep searching my library.

The californian models did have a more strict regulations to follow, but that didn't include a charcoal canister.
The fuel tank ventilation did lead the fuel vapors (sometimes also raw fuel   ) to the crankcase via a non return valve.

That hose went to the vent on the top front of the engine.

Because 100 molecules of gas would harm California's air quality.

RicK G wrote:I can't find any reference to it but I think that the Californian regulations caused them to be fitted.
I shall keep searching my library.

Mine is an 1988 with the time fuel vapor recovery system, originally the vent hose goes to the engine crankcase via check valve, drain one goes back to floor.
There is a BMW service bulletin that  recommends to take out the check valve and extend and redirect the vent hose parallel to the drain one  and cap the crankcase tie in.
This to avoid over rich mixture and oil contamination on hot weather.
No charcoal, direct atmospheric vent
Best regards
JAP

Yeah OK I stand corrected maybe I confused it with something else, different bike.
I think I need to go for another ride but I wont tell my physioterrorist she says maybe in time for the June Alpine Rally 

RicK G wrote:I wont tell my physioterrorist she says maybe

We have the correct one for you here in Norway....she's called Else.....for your Norwegian lessons:

Arrrgggg!!! that is physioterrorism, mine is a little more gentle and insists that I do some of the torture.

So I'm still unsure from the responses what I should be connecting on my particular model? Am i connecting the hoses to the vent pegs coming out of the bottom of the tank?

Yes, both hoses should be connected......if both hoses points to the rear, it doesn't
matter which hose you connect to which spigot.
If one of the hoses points to the front, this hose should be connected to the most 
forward spigot.

If you get the earlier mentioned plastic cup, you don't have to mess with these
hoses when removing the tank (a rather tight space)......part # 16 13 2 307 467.
If one of the hoses is pointing to the front, this hose must be blinded...if the cup
being mounted.

Ok thanks. One of the hoses doesn't seem to be connecting to anything at the opposite end of the fuel tank?

Both hoses would  be very happy to be out in the open air, in the opposite end
of the tank connection.

You can order the cup froma dealer or give re-psycle (in OH) a call.  They may have a used one.

Thanks for all the help. I need some further guidance on securing the tank. Currently the only thing "securing" the tank is when I slid the back of the tank into the frame (shown on the 1st picture above the fuse box).

I've included 2 pics below.

- In the 1st pic, where do I secure the open bolt hole up above the yellow sticker?

- In the 2nd pic, where do I secure the open bolt hole that's facing the fairing?


Thanks!





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Those are both holes for grommets to attach  body parts.

#1 - side cover

#2 - radiator shroud on a naked K100

Thanks duck. My tank still doesn't feel secure. Looking at pic #1, does it look like I have the 2 bolts in correctly? They just slid into the frame bracket, they are not secured with a nut or anything else.

The posts at the rear of the tank should go through rubber grommets in the frame (16111455167) and be secured by C-clips (07129934336).

Also check the dia. of the posts, it was a change 05/91 from 10 to 8mm.
(put your frame no. in the signature).

8 mm grommet part #16 11 2 309 163.
8 mm c-clip part #07 11 9 932 863.
.
.
10 mm c-clip part # 07 12 9 934 330

[quote="duck"]The posts at the rear of the tank should go through rubber grommets....and be secured by C-clips (07129934336).
GRAVITY

The only problem with that is that in a getoff when your bike is sliding on it's side and runs into something like a curb or whatever that GRAVITY has nothing to do with holding your tank in place.

It is surprising just how many are held on with Gravity Glue.

RicK G wrote:It is surprising just how many are held on with Gravity Glue.

It's probably more grommet glue than gravity glue. LOL.

In the end though, it's a matter of personal preference.  Me, I'd just as soon that the tank remains attached to the frame in a getoff.

This will soon parallel oil threads....

duck wrote:The only problem with that is that in a getoff when your bike is sliding on it's side and runs into something like a curb or whatever that GRAVITY has nothing to do with holding your tank in place.

True, but at that point I will be thinking of that K1 I cannot afford to buy without the extra $2500 the insurance company put on the value of my wrecked of my bike.

And trying to get away from the fuel spill being rapidly lit by the spray of sparks.

And wondering where the post on the forum was about the value of C clips on your tank.

The tank is aluminum, how many sparks do you think that will create?

Just checked mine. No clips!  But must be an overabundance of gravity
cause it was still pretty hard to lift. Underneath the tank one of the vent
tubes was disconnected and the other was pinched between the tank and frame. The disconnected one goes under the bike to the back, but the other
one was only a few inches long with a little round disc thing on the end with a small hole in it. I replaced the disconnected one, but the short one with the disc thing just dangles under the tank. should I replace it with a longer
tube and run it to the back like the other one and leave off the little disc?


Hey mack8882, Nice looking new paint! cant wait to do mine. 

From reading the Clymer manual I was under the impression that only the K75 used the clips? Mine had them but I think it has a K75 tank on it now, and they didn't seem to do anything anyway - I simply pulled them out of their hidey hole with small pliers, no clipping was being done. I have left them off, the grommets seem more than capable of holding it in place.

Can't help Dale though, no idea what he means. I just have open pipes on the tank pointing into a cup, like most people.

More on "the cup" here: http://classickbikes.com/ckb.tech/0.ckb.tech.files/thecup/thecup.htm

Thanks duck, helpful link! The cup does seem a better solution than the hoses. I'll try to find one. The disc turned out to be a one way check valve.

Hi there, just be sure that the "vent on the top of the engine block above the middle of the timing cover" where the hose downflow the  check valve used to be tied is properly caped, else you'll have air leaking related problems.
Best regards
JAP

Yeah I was wondering about that. I'll take a look for the vent when I pull the air cleaner to change out the fuel return hose to FPR.