Vintage CB Motorcycle PetcocksFuel Valves

bySalem

1.7K followers

8 years ago

Motorcycle World - Tip 1

Fuel Petcock rebuilds - Brass Tubes/ Straws

Vintage fuel petcocks can be especially hard to find parts for. You can find most gaskets and innards of the petcocks but you will often not be able to find or even order replacement brass tubes (sometimes referred to as straws) which project upwards from the petcock into the fuel tank. Gasoline flows down these tubes, into the petcock and then to your fuel line filter and carbs. When the gasoline level goes down to the point it can no longer flow over the top of the tube, your engine starts to sputter from lack of fuel. This in turn tells you to switch over to your reserve which is either a lower straw or no straw at all on the reserve side of the petcock.

While today, most of these straws are made from various materials impervious to gas, the older fuel petcocks often have these brass tubes. These brass tubes are sometimes found missing when you buy an older bike or, like in my case with my 1971 CB500 four, was split. This meant I had no reserve.

After searching every conceivable motorcycle parts outfit I could find in North America with no luck, I finally noticed on a forum that someone recommended the local hobby store. Sure enough, they carried every size you could need. Their brass tubes are sized so that the outer diameter of one tube will just snuggly fit inside the next size up. I simply used a small copper tube cutter and cut the size I needed. I then polished one end with 1000 grit sandpaper and gently tapped it in the petcock. Problem solved for under $4 dollars and I have enough tube left for another three tubes.

If you do not already have a tube to measure its thickness, you can take the petcock itself with you to your local hobby dealer to check the fit. Ride Safe......