This the pre-MkIII assembly. Seems like a lot of parts. I think, from what I can tell, not many bikes still use this contraption.


I have the T fittings and could make it that way.


This is the MkIII assembly. That is how I first mockup up my carbs, except I think I have Triumph banjos, which may have an angle instead of 180º fittings.



Which fuel lines are you using?

swooshdave The H type is the one that cam on my 74 when I bought it in 75 It will have a new one when Im done rebuilding it Phil

Mine has the original 'H' set-up. Yellowed and brittle as hell. Can't believe DPO never replaced it. Well it was sitting for thirty years so that may explain why.

Will be using the latter type configuration.....when I finally get to the carbs!

Blimey, didn't know you could buy them made up. I use black fuel hose, looks neat. Use the latter configuration, but did originally have the H type.

Anglophile wrote:Mine has the original 'H' set-up. Yellowed and brittle as hell. Can't believe DPO never replaced it. Well it was sitting for thirty years so that may explain why.

Will be using the latter type configuration.....when I finally get to the carbs!

I literally had to cut the old lines apart using a Dremel.

Dave Did you try a heat gun Im going to try it on my old one Phil

Norton-Villier wrote:Dave Did you try a heat gun Im going to try it on my old one Phil

I was afraid of melting the plastic fittings. I ground away the old hose very, very carefully and when it was almost through I pried it the rest of the way off.

The 750 models used the 'H' set-up with plastic 'Tees'. This was changed to the double banjo for the 850's, I believe in '74. The problem with the 'H' set up is the cross over is quite close to the back of the cylinder.

I make up my fuel lines with polyurethane tubing. This tubing discolors as badly as the old vinyl, but it does not get hard and brittle. I also try to use metal 'T's and metal banjo's when I can find them. The old style monobloc carb banjos were usually metal, but sometimes need to be drilled out to fit the concentrics.

The closeness to the cylinder is only an issue if a head gasket blows out at it weak spot where the oil drain hole is, then jets of combusting gas directly hits the fuel line and will cut it to spill flame in about 30 sec. I remembered this about 15 sec into Trixie Combat's blow out and a few more to get stopped with just seconds to spare. Replaced back gasket and repaired clear factory fuel hose by silicon and heat shrink as still held fuel. New clear hose kit by factory number goes on this season.

hobot

Hi Dave
I think Ron is right that the change was due to the possibility that a blown head gasket might heat things up enough to cause some unwelcome fireworks outside of what goes on in the engine at the 28 degree spark BTDC.
Don't Quote me but I think IMHO this was the reason.
May be more knowledgeable folks confirming this???
CNN

Ron L wrote:I make up my fuel lines with polyurethane tubing. This tubing discolors as badly as the old vinyl, but it does not get hard and brittle.

On my Bultacos I've used Tygon, great stuff, won't harden and is translucent so you can see the fuel.



Wakula Racing Tygon

With the banjos I have I don't think I can do the newer style setup. I might try the H style until I can find the right banjos.

swooshdave wrote:With the banjos I have I don't think I can do the newer style setup. I might try the H style until I can find the right banjos.

Yes, the 150°double banjos are for Triumphs.

The 180°double banjo for 1/4" pipe is Amal part 376/419


http://www.amalcarb.co.uk/default.aspx

L.A.B. wrote:

swooshdave wrote:With the banjos I have I don't think I can do the newer style setup. I might try the H style until I can find the right banjos.

Yes, the 150°double banjos are for Triumphs.

The 180°double banjo for 1/4" pipe is Amal part 376/419


http://www.amalcarb.co.uk/default.aspx

Before I bastardized my bike with the Mikuni TM, I liked the way the 150's tucked in and pointed to the petcocks, and the 5/16" pipe. 376/139

I was fortunate to have an A-N new asembly in a box of bits which came with mine - fitted perfectly and hasn't gone brittle or opaque in over 2 months of hard use

I'm still dismayed by the costs of the fuel line assemblies but those fittings are more expensive than you would think. The banjos are about $10ea from Amal and the ones that go to the petcocks have to be at least that much. There's $40 right there before hose and crimping. No wonder they are $50+ for the whole thing.