Hitchcocks Forum

There are 2 tubes of different sizes runnin to and out of the breather box. My question is what size are they. And composition of materials used?

I can`t help you with the sizes; but if you take a sample to a Fish Tank/ Pet Shop, they sell plastic hoses for the filters, which I have used for the 2000Bullet. You might be lucky.

Just measure the diameter of the pipe stubs on the breather box for the inside diameter of the hose, I think the larger one is 10mm. They're probably nitrile rubber.

A.

One of them might also have a non-return valve built into it (the one running to the timing chest) but there are variations on this theme across the range.

With the use of modern oils and fuels, any rubbery pipes I get for any of my vehicles, is either silicone or viton, synthetic oil and ethanol just destroys rubber, the same goes for 'o' rings and oil seals as well.

You're better off without the breather box altogether IMHO

Thank you for your insights. So the simple solution is to plug return line,and run feed line to rear?

On my 05 Bullet, the bigger breather hose is 10 mm id. I went to a motor factor and bought some 10 mm breather hose, my plan was to replace the stock breather hose, which has a right angle bend as it exits the stub, which I think acts as a trap for goo, with a straighter run to the catch can. however, I ran into a snag ; the hose appears to flare out as it slips into the catch can pipe, so I had to abandon my plan, as the hose would just not go. The stock breather hose seems to be 10 mm at the crankcase outlet, but flares out to about 12mm at the catch can.

Yes, blank off the return to back of timing chest, run breather to rear ( to chain if you like) and dump the catch can altogether. Blank off the pipe to the air filter too.
It was a poorly designed anti pollution device and never worked properly.