As the name suggests, this has the outer cylinder pipes made from larger bore tube (1 3/8" O.D.) and is "one piece" from the head through to the Silencer.

The center port pipe is the same as the stock Manifold.

I can set this Big Bore pipe up to suit either the Raygun or Mega-phone Silencer, or any particular Silencer that you would like to use.

This photo shows this Big Bore pipe fitted with the stock '71-'72 Mega-Phone Silencers (3017)

The '69-'70 Raygun Model (3017-1)

To use the Raygun Silencers two short adapter/clamp piece's are required. (3017-2)


Construction.

When building these Big Bore pipes I constuct the two 1" inner pipes, bend up the two outer pipes and set them in my Jig, which is this case is an actual bike.

I then scribe around the joint where these two inner pipes meet the outer pipes,

I then remove the outer pipes and cut this oblong shaped hole.

This is about 20mm wide by 60-70mm long.

This ensures that there is NO restriction of gas flow from the center port to the two outer pipes.