Fuel line hose replacement at air intake assembly

[daamo]

Hi everybody, this is my first time on the forum. Am owner of a 1985 R65 bought last summer.

Am wrestling with replacing leaky fuel lines and amazed I can't find any other forum entries on any website with an explanation of how the installation works properly.

Once the lower air cleaner housing is opened up I removed the three bolts anchoring it to the engine - bolt at center (down), stud at right, and long bolt to left. I replaced all the hoses a month or so ago, but found that in putting it all back together the hose that passes along the front of the air cleaner housing was totally munched, constricted, and now I'm doing it again.

I see in my Clymer's and the maxbmw website, that there's also supposed to be an additional nut between the engine and the air cleaning intake housing for the right hand stud. Doesn't this a) further munch the fuel line which passes right there and b) misalign the center-down bolt? This whole assembly is quite the swiss watch - there seems to be less than adequate clearance for this hose.

Hope this reaches someone who has a moment to answer.
Thanks, all
daamo

[chopper_harris]

My '85 is a Mono, but the engine is the same.

No, only the three bolts - one into the g/box, and two into the block (And that is overkill).

Are you using a modern, braided fuel hose intended for pressurised FI systems (40-60 psi) ?

The correct hose is 6mm bore, and I find that Gates fuel hose is excellent.

[Justin B.]

Maybe you're thinking of the spacers between the airbox and engine block, they don't "munch" anything.  I use 1/4" clear polyurethane line and I have replaced the hose running between sides with a chunk of steel line as a test.  So far the steel line is working out great.

[Ed Miller]

I was going to try that, Justin.  What size line?

[Bob_Roller]

Hi everybody, this is my first time on the forum. Am owner of a 1985 R65 bought last summer.

Am wrestling with replacing leaky fuel lines and amazed I can't find any other forum entries on any website with an explanation of how the installation works properly.

Once the lower air cleaner housing is opened up I removed the three bolts anchoring it to the engine - bolt at center (down), stud at right, and long bolt to left. I replaced all the hoses a month or so ago, but found that in putting it all back together the hose that passes along the front of the air cleaner housing was totally munched, constricted, and now I'm doing it again.

I see in my Clymer's and the maxbmw website, that there's also supposed to be an additional nut between the engine and the air cleaning intake housing for the right hand stud. Doesn't this a) further munch the fuel line which passes right there and b) misalign the center-down bolt? This whole assembly is quite the swiss watch - there seems to be less than adequate clearance for this hose.

Hope this reaches someone who has a moment to answer.
Thanks, all
daamo

When you have the air box off again, just enlarge the opening with a file, prime and repaint the bare metal , if you like.

After you do that, you don't need to remove the air box again for fuel line replacement .

I like the idea of using clear fuel line, but I kept getting a kinked line on the right side when I installed it.

[montmil]

Just replaced the fuel lines on my '81 with Gates 0.250 i.d. line from NAPA.

I was wondering about the same issue; how to pass the fuel line through the air box without opening up the chamber. Sorta like trying to push a rope uphill, right?

I ended up straightening out a wire coat hanger and running it all the way through the square-ish opening for the fuel line and out the other side.

Next, I wet down the outside of the fuel hose with Liquid Wrench silicone spray, fed the fuel hose onto the wire and pushed it through. Wow! It popped out the other side. Fit to the right-hand carb then trim the length to fit the "T".

Monte

[Bob_Roller]

Monte,

The only material you have to remove is where the fuel line touches the airbox when it enters and exits the airbox.

The metal is only at best 3/16ths of an inch thick at each spot, it's all empty space in between, not a channel, where you would have to remove metal all the way across the airbox casting.

[montmil]

Monte,

The only material you have to remove is where the fuel line touches the airbox when it enters and exits the airbox.

The metal is only at best 3/16ths of an inch thick at each spot, it's all empty space in between, not a channel, where you would have to remove metal all the way across the airbox casting.

Roger that. I had the box open the day before while replacing the air filter and doing some house cleaning inside it. I just didn't have the energy to open it up for the fuel line replacement.

IIRC, would not enlarging the air box cover opening permit some small amount of unfiltered air to enter the intake system?

Monte

[Bob_Roller]

No it won't let any air in, as there is no opening into the filter area, it's just an empty cavity area between the airbox, and the transmission.

[Justin B.]

Ed, I don't remember exactly but I think it was 1/4" and I put just the slightest hint of a flair on each end...

[drewboid]

From what I remember the standard braided 6mm BMW hose is SLIGHTLY thinner than US 1/4 inch hose.  that makes the US hose hard to thread through the openings in the air filter box. The slight difference in size also means a looser fitting at the carb, tank and T.

[montmil]

... The slight difference in size also means a looser fitting at the carb, tank and T.

Perhaps the Gates hose has a thicker wall and/or slightly smaller i.d. as I had to use a silicone rubber lube just to get the hose on the petcock, the 'T' and carb fittings. It is tighter'n a tick!   YMMV

Monte

[nhmaf]

I like Monte's idea to use a coat hanger to thread the hose back through without having to loosen/remove the airbox.

[Semper Gumby]

Cool tip Monte.  Doin' pretty well for a guy with one eye...ARRRRR!  

[montmil]

Cool tip Monte.  Doin' pretty well for a guy with one eye...ARRRRR!  

Pity me, fellow pirates... I have to return to work tomorrow.  [smiley=beatnik.gif] sorta hippy pirate, uh huh.