Exhaust diameters

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Nov 11, 2004
I have just purchased some new original peashooter mufflers for my Mk3 Commando. The outside diameter of my (non original) exhaust pipe is 1.5 inches, which corresponds with the outside diameter of the bit of the muffler that is supposed to fit over the exhaust pipe, meaning that they wont fit.

Can anyone tell me the diameter of the original exhaust pipes, and what the diameter of the muffler "sleeve" should be?

Looking at the Norvil website makes me suspect that there were two different exhaust diameters available.

Original pipes are 1 3/8 inch diameter. 1 1/2 inch "peashooters" are available by Viking thru Old Britts and others. However, Mk III Commando "stock" mufflers were the "black cap" annular discharge type, not "peashooters" if originality is what you are striving for.
When people talk about 1 1/2 inch exhaust pipes where are they measuring?

The headers on my Mk IIa 850 are 1 3/4 inch at the engine and approx. 1 1/2 inch at the junction of the header and muffler.

I would guess that this is a 1 1/2 inch system.

I've been wrong before.

Any suggestions on replacement pipes - location Sydney, Australia.
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