Cutting Stock Exhaust

[pamcopete]

The stock headers are double walled. The functional pipe is inside the outer pipe, so if you are going to use the stock headers with an after market muffler, you need an adapter that will connect the muffler to the smaller inner pipe. And, yes...the outer pipe does have drain holes in them, so if you just clamp the muffler to the outer pipe, the exhaust will leak out of the drain holes.

The outer pipe may also leak at the head flange as well. The outer pipes were not designed to flow any exhaust, so there is no guarantee that they are gas tight from end to end.


I used this adapter on my '81/H:

This is a 1 1/2 X 1 3/8" adapter available at most auto supply stores, #548520. The small end will fit tightly around the outside of the inner pipe. Clamp the muffler around the large end. There is no way to clamp the small end around the inner pipe, but it fits real tight, so you can either wait for the carbon buildup to seal it or apply some Permatex muffler sealer.

Edit 3/2023 a pic of the common 548520 reducer

The small end is completely hidden inside the header, the big end is completely hidden inside the muffler.

This is what it looks like when installed.

 

[Paul75]

Hopefully I nailed it!!!

 

[YamadudeXS650C]

Very nice, tasteful build, Paul.

BTW, the aforementioned request by Paul S. for the reverse NGK (KGN) caps reminds me of the Garage thread discussion in April of the rare Special Edition AHAMAY, of which I have a nice example, purchased last fall. It features a right-hand drive, left-hand kicker, and AHAMAY logos on the case and tank.

 

[Paul75]

That's certainly unique!!!

 

[YamadudeXS650C]

I believe that the AHAMAY model was made for the riding public in the UK; you know, those British chaps and their penchant for right-hand drive....