What size is the fuel line on CB400F2 / top engine breather pipe termination ?

[McCabe-Thiele (Ted)]

After fitting the air box after a fashion I realise I should have connected the fuel pipe!
Old pipe is so deteriorated I can't get a decent diameter measurement.

What is the correct size/diameter I should fit please ?

The breather pipe from the top of the engine cam cover seems to just end under the seat should it be connected anywhere ?

[Bryanj]

5.5mm for fuel pipe, dont know about breather

[taysidedragon]

The engine breather hose goes down the back of the air box and connects to the cup thing underneath the air filter box.

[McCabe-Thiele (Ted)]

The engine breather hose goes down the back of the air box and connects to the cup thing underneath the air filter box.

Thanks for that the cup thing on mine has been part painted black so I never spotted it there is the male pipe connector staring at me! My old hose is a straight piece with original looking clips so I guess the original was not moulded with any bends.

[McCabe-Thiele (Ted)]

5.5mm for fuel pipe, dont know about breather

Is that 5.5mm o/d presumably 3.0mm i/d any tips on whether it should be cotton braided or where to buy from please..

[Nurse Julie]

5.5mm for fuel pipe, dont know about breather

Is that 5.5mm o/d presumably 3.0mm i/d any tips on whether it should be cotton braided or where to buy from please..

The main fuel pipe is 5.5mm ID and the carb overflow pipes are 3.4mm I'd. Non cotton braided, you can get everything from Planet Silicone on ebay.

[McCabe-Thiele (Ted)]

5.5mm for fuel pipe, dont know about breather

Is that 5.5mm o/d presumably 3.0mm i/d any tips on whether it should be cotton braided or where to buy from please..

The main fuel pipe is 5.5mm ID and the carb overflow pipes are 3.4mm I'd. Non cotton braided, you can get everything from Planet Silicone on ebay.

Thanks I really need to get my head round metric sizes as they mean little to me so its 5.5 mm i/d not o/d. lol

[Bryanj]

You got a Honda so EVERYTHING is metric

[McCabe-Thiele (Ted)]

You got a Honda so EVERYTHING is metric

Surprisingly a lot of the early Japanese Car Engines used imperial sizes as OEM. Back in 1978/9 the firm I worked for had a pick up can't remember if it was a Toyota L2 or the Datsun equivalent. Anway the big ends went so we had to have the crank ground & re-shelled. All the bearings were standard BLMC sizes due to the fact that the manufacturers bought a load of old BLMC machinery and obsolete engine manufacturing rights. The crank turned out to be straight out of an old Austin A60 or similar except with a different crank taper. !

[SeanFD]

The fuel hose is 5.5mm ID and 10.5mm OD.

The breather pipe is 12mm ID and, about, 15-16mm OD at the top and bottom.