Paso 750 manifold - header pipes question

[Hifimoto]

My bike came with removed exhaust silencers and manifolds. I’m at the end of restoration and I tried to install them, but I was faced with the problem: the rear header pipe for the vertical cylinder is 35 mm diameter, the front header pipe for the horizontal cylinder with the pipe junction have 40 mm diameter and also 40 mm diameter for connection to the vertical cylinder pipe. So one of the headers is not right. Funny thing is that both have correct part number on them (vertical 037084030, horizontal 037084020)

My question is: should it be both pipes 35 mm or both 40 mm? Is this the difference between EU and US version? Or is it maybe 40 mm header pipe from some other Ducati bike (SS or Monster)?

Can somebody please measure the header pipes on their EU version Paso 750?

I’m buying a beer!

Ducati headers.jpg (385.61 KiB) Viewed 14365 times

[Mc tool]

Im thinkin that the rear header is narrower because its longer , so as the two headers have the same internal volume . The mis match of the rear header and junction is because there is a gasket/sleeve thing that goes in there too ?

[Hifimoto]

I thought initially the same... but it doesn't seem logical. The longer pipe (vertical) would be wider, the shorter (horizontal) narrower for the same pressure.

There is no gasket in the parts catalog. I'm quite confused...

Manual.jpg (122.94 KiB) Viewed 14355 times

[Tamburinifan]

"Or is it maybe 40 mm header pipe from some other Ducati bike (SS or Monster)?"

My guess too.
600-750 had smaller I/d.

[paso750]

https://forums.ducatipaso.org/viewtopic.php?p=55400

[Hifimoto]

Great, thank you very much for your kind help!

It confirms an odd situation with the part numbers. So, I need vertical header with 40 mm diameter or horizontal header with 35 mm diameter... both need to be the same. And from what was said in the older post, I conclude that the EU version needs to be 40 / 40 mm.

Back to search for the 40 mm vertical header...

Thank you again!

[Hifimoto]

Additional information about the exhaust for paso 750: there are actually three versions of manifold for it. And confusingly, they all have the same SN on them:

- narrow version: 35 mm diameter (US version)
- normal / wider version with two rings attachment for cylinder head: 40 mm diameter (EU older version)
- normal / wider version with one ring attachment for cylinder head: 39,4 mm diameter (EU newer version)

So you can’t really combine the latter two if you want a good seal between the pipes.

[oilyrover]

One of the header sets I have that I need to re-home has the double ring set. Anyone interested should PM me.