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Can anyone tell me please what the correct INTERNAL diameter is for replacement fuel pipes on my 1980 R100RS.

6mm and 8mm seem to be the popular sizes avilable aftermarket. Ideally i want to buy some ethanol resistant pipe.

Cheers Darryl

If I recall correctly, (unlikely) 7mm is the go. where to get it, not sure.

6mm too small, 6.5 (1/4") bit small too.
8mm prolly too loose.

I think I've got 6.5mm on my bike and find a little grease helps with the off and on. I don't use clamps.

A trick I've heard people suggest is to slip an appropriate sized washer between the end of the hose (pipe?) and the petcock barb. This gives you something to grab onto and help slide the hose off next time.

Kurt in S.A.

I gave up on the OEM braided hose as it always seemed to go porous on me. I just use a good quality 1/4" fuel hose.

Kurt in S.A. wrote:A trick I've heard people suggest is to slip an appropriate sized washer between the end of the hose (pipe?) and the petcock barb. This gives you something to grab onto and help slide the hose off next time.
Kurt in S.A.

I like that
Thanks Kurt.

I also gave up on using the braided OEM type hose. Expensive with no value added. Now I just go down to the local auto parts store and purchase 1/4" ( 6.5mm ? ) fuel injection hose. No problems on/off and I also don't use clamps because there is no need

I've been using the washer trick for a long time...VW shops usually have the metric braid-cover hose if you like the vintage look but recently I've had good luck with 1/4 inch fuel hose (it's undersized! and quite tight): SAE 30R6 KX (not sure about the "R") Also bought from NAPA off the reel in any length I need. I usually get 5 or 6 feet at a time.