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Just replaced the ones on mine with some decent thick walled pipe that does not kink.

Guess the ones that were fitted were the OE ones - clear plastic ?

I replaced them because where the PO had used cable ties to stop the pipes flapping around they had become restricted, which is probably not good for engine breathing.

Originality does not matter to me, and the new black pipes look just fine and as they are thicker walled less likely to kink, so were the plastic ones that are now in the bin OE fitment?

The originals on my 1978 were clear/opaque plastic, approx 5mm bore. In its time, mine has had fish tank air hose, black rubber pipe and currently has PTFE hose with rubber 90° elbows on it. As long as it flows some air and any emulsified oil can escape it will be ok.

Yes, I believe the original breather pipes were clear flexible plastic. Over time they would become more yellowish and get harder. I'm fairly sure the ones on my bike are the originals (1983) as they are a deep treacly orange colour and would probably snap like a carrot if I tried to bend them! They are doing the job so I'm not too worried.

As far as I know the same goes for the crankcase breather with the baffle in it. Alex at NLM changed mine about 25 years ago, I can't remember why, and he replaced it with a clear plastic pipe which is still fairly clear looking and quite flexible.

I have seen some breather pipes with a slightly green hue but I think they must be modern replacements.

Yep, mine had become yellow and hard where they fit onto the rockers, but were quite soft further down, hence the kinks which were restricting the pipes a little.

I have seen that pipe with the green hue - guess it really does not matter what you use as long as there are no restrictions.

Crankcase breather is still nice and flexible and has the "baffles" in it.

I fitted some "ethanol proof" fuel lines shortly after I bought the bike as the ones that were on it were quite hard and inflexible.

Andy_C wrote: ↑21 Aug 2025 20:04 I fitted some "ethanol proof" fuel lines shortly after I bought the bike as the ones that were on it were quite hard and inflexible.

Absolutely the right thing to do.

I'll be replacing mine soon.

I remember the days when we didn't ever worry about such things. You could even leave a can of petrol in the corner of the garage for a few years and when you put the fuel in the bike it would run with no problem. Hey ho.

Morini Jen wrote: ↑21 Aug 2025 20:44

Andy_C wrote: ↑21 Aug 2025 20:04 I fitted some "ethanol proof" fuel lines shortly after I bought the bike as the ones that were on it were quite hard and inflexible.

Absolutely the right thing to do.

I'll be replacing mine soon.

I remember the days when we didn't ever worry about such things. You could even leave a can of petrol in the corner of the garage for a few years and when you put the fuel in the bike it would run with no problem. Hey ho.

Aye, when I were a lass everything were different... we had fresh bread every day, a milkman and a pound of monkey nuts cost 3d

Actually, looking back, things were different. Wouldn't want to go too far back to the times of ricketts and tuberculosis, though!

Mickey

Cue the Monty Python 4 Yorkshireman sketch.............

Jen

I can recommend some pipe named "Ariete" it seems to be genuinely Ethanol proof.

That is what I have on mine as well as my KH 400.

Andy_C wrote: ↑22 Aug 2025 11:59 ...I can recommend some pipe named "Ariete" it seems to be genuinely Ethanol proof...

Thanks for the tip Andy.