Bridgestone 350 Air Filter
The Bridgestone 350 is a wonderful piece of modern engineering. Perhaps some of the best from the world of 1960’s motorcycling.
One of the weakest points is the air filter. As we all know the cylinders are chromed, pistons are aluminum while the rings are cast iron. This all adds up to long term durability, provided the proper oil is used, and clean air is all that goes through the engine. This system will last well over 100,000 miles.
The Bridgestone 350 greatest shortcoming is the silly air filter, it uses only a fine wire mesh with a thin flocking material applied to it. This air filter is totally worthless. The flocking comes off, being drawn through the engine, along with all kinds of dirt.
Dirt is the WORST enemy to chrome plated cylinders, fine dust particles act like sand paper, wearing out the chrome at a fast rate. Today, new 350 cylinders are in sort supply and re-plating them is very expensive, and in many cases just does not work.
The solution before the cylinders are worn is simple, but it involves a few steps:
Remove the air cleaner cross over case (6221-9000), in which the mesh is bolted inside. (6214-9000)
Remove the mesh, inspect and clean all old flocking off of it.
Using a foam filter from say a 1970’s Husqvarna motorcycle, split the filter long wise and glue the edges of the filter to the
edges of the BS wire mesh, allow some material to overhang the edges, so there will be a tight seal between the mesh when you reinstall it in the
cross over case. The main idea it to make sure there is no place for dirt to “get around” the filter. Do this to the under side of the mesh.
Use new gaskets (6225-9000) between the cross over case and the carburetor aluminum covers.
Use new carburetor aluminum cover gaskets too. (2186-9000 and 2185-9000)
Make sure the carburetor rubber caps are sealing tight too. ( 2177-9000 and 2172-9000),
these are the rubbers that the control cables go through.
Install new carburetor removal hole rubber plugs. (2168-9000)
This small modification will make your Bridgestone 350 last for many years.
Richard Clark
