View Full Version : Triumph, Norton, BSA exhaust question

01-18-2011, 11:37 PM
What's the common size dia pipe used for exhaust ? Triumph, Norton, BSA ?
1.75" ?

01-19-2011, 12:15 AM
both preunit and unit twins are 1.5 inches on the pipes od
heads ports are 1.5 inches id...hope that's what you wanted to know

01-19-2011, 9:52 AM
1.50 or 1.625 are the typical sizes. some will go up to 1.75

01-19-2011, 10:18 AM
from what I know about Triumphs.... the 500's were 1 1/2", the early pre units were 1 3/4", and the late pre units and units were 1 5/8".
Norton's were 1 5/8", I can only assume BSA was the same as Triumph.
a little back pressure is a good thing, large open pipes make great noise but not great power.

01-19-2011, 9:56 PM
thanks all