Carburetion and Fuel Injection

Carburetion

• This page has an excellent explanation of how carburetors work.

Rebuilding

• Serius Consolidated Inc sells carburetor rebuild kits, which seem to include:
  • float bowl seal
  • top cap seal
  • float needle
  • o-rings
  • main needle and clip
  • main jet
  • pilot screw.
• Partsnmore sells somewhat less comprehensive rebuild kits for vintage carburetors.
  • float bowl seal
  • five o-rings
  • top-cap fiber seal
  • float needle
    • Compare the Sirius kit to the Partsnmore kit for the 1978 CB750.

Petcock

Sealing

• This thread discusses how to seal a weeping British petcock.
• Jomar Gimme the Green Stuff is a soft-setting sealant which should prevent gasoline seepage.

Connectors

Quick Disconnects

It's often nice to have a quick disconnect on your fuel line to make tank removal much easier. There are several options, and most of them are probably bad.

Regarding quick disconnect fitting barbs, here is an excellent explanation of why clamps shouldn't be used on barbed connectors, and how to use them correctly on beaded connectors.

Plastic

Colder Products Company

CPC sells plastic (Acetal, I believe) quick-disconnects. They're available with Viton O-rings, which is a must-have when dealing with gasoline. They're available in shut-off and free-flowing versions. Presumably, you'll want the ones that shut off when you disconnect the two halves.

CPC supplies connectors to BMW, and there are many examples of the male side of the connector failing on BMW motorcycles, particularly the LT models.

Additionally, they have a maximum rated temperature of 180 degrees Fahrenheit, which really isn't very high if it's going to be near hot engine cases and especially if they're anywhere near exhausts.

McMaster-Carr

MCMaster-Carr sells various plastic bodies that are likely comparable to the MotionPro and CPC connectors.

Metal

CPC also makes a chromed brass series (it still uses plastic internals). The problem is, it's still rated to the same 180°F temperature limit! The metal disconnects sold by Omega and AF1 Racing are CPC LC-series connectors.

The other problem is that all of these options are quite expensive. For example, a 1/4" complete connector (male and female sides) chromed brass version would cost $37.49, plus shipping, from quickcouplings.net. In my case, I need two sets of connectors since I have two fuel taps. That's $74.98 for a set of connectors that still might fail being so close to a hot engine and exhaust.

Jiffy-Tite

In my opinion, this is the best option. Jiffy-Tite are made of machined aluminum, use Viton O-rings, and are even made in the USA. They're expensive, but actually available for around the same price as the CPC metal connectors, and seem to be the cheapest metal option available.

A kit intended for the BMW bikes is available from Racer Parts Wholesale, also known as Racer's Warehouse, I think for $79.99 (or on Amazon for $72 + $7 shipping). It's for 5/16" hose and comes with high quality clamps. A version with right-angle fittings is available for $84.99.

Fuel Hose

Materials

Nitrile (abbreviated NBR) is moderately affected by gasoline. Viton B Fluoroelastomer (abbreviated FKM) is the most highly resistant to gasoline.

Consult Custom Advanced Connector's Chemical Resistance Chart to compare materials.

Gates

For carbureted applications, Gates Barricade Carburetion Hose (SAE 30R7) is the only option I've found which uses a Viton (FKM) liner. 5/16" hose is available from Oreilly Auto Parts for $1.99 per foot. Note that the Gates product brochure recommends that beaded stems be used rather than barbed stems, claiming that barbed stems are for use with plastic tubing only.