different Paso headers

[paso750]

I was discussing offline with Antti about exhaust cans and headers and I guess it`s time to post this also here.

Measuring intake diameter of P750, 906 and 907ie exhaust cans we confirmed that all have 40mm inner diameter. So they are all interchangeable (from the mechanical point of view. Usually exhausts are designed to match the engine characteristics so a P750 silencer may not work properly on a 906 ie because more restrictive but that`s another story and not part of our investigation).

The difference between the US and the european header is the tube diameter from the cylinder to the header cross. The header tubes coming out the cross going to the silencers are the same on all Paso headers. (incl. the Limited models)

The Paso 750 parts catalogue lists:

horizontal header
0370.84.020 (validity f.m.) - inner diameter 37mm, outer diameter 40mm
0370.84.023 (validity d.m.)
0370.84.220 (US)

vertical header
0370.84.030 (validity f.m.) - inner diameter 31mm, outer diameter 35mm
0370.84.033 (validity d.m.)

Ian Fallon mentions the racing uprating kit in his Duc 2 valves restoration guide and it`s the header 0370.84.023 + 0370.84.033. As the vertical tube is the same as on the european standard header, the tube diameter of the front header must also be the same so actually the only difference between the standard european header and the Limited header must be the header crossing.

It must be similar for the 906 because there`re 2 horizontal headers listed but only one vertical header tube.

G.

[Tamburinifan]

Seems a bit odd.
Usually 750 pipes are 35mm o/d and not fitting 900`s due to different stroke.
So a Eu 750 has 2 different dia pipes?

[Finnpaso]

I measured just diameters from my 750 Paso. My bike have that Ian Falloons mentioned "kit" (as Limited have also)from since of totally new.

Front sylinder header outside diameter is 40mm
Rear sylinder header outside diameter is 40mm
From "crosssing part" to end of pipes(where mufflers start!) are also 40mm

So, whole header system is made from 40mm tube(outside diameter).

Gerhard made great job again!

btw, also 907IE have same diameter (40mm) header pipes. Measured just.

It can be, that 750 Paso "kit" was designed to more tuned 750cc engine, as its same diameter, as 907 with 904cc engine... Anyway i havent had any problems to use that kit with "not tuned" 750cc paso engine....

[paso750]

Usually 750 pipes are 35mm o/d and not fitting 900`s due to different stroke

Are you referring to silencer or header ? If you`re referring to the intake diameter of the silencers you`re wrong. All headers have the same output outer diameter. (I do have a P750 and a 906 header and they are both identical in tube diameters. The difference is the length of the header tubes from cylinder to cross)
If you refer to the tube diameter of the header (from cylinder to cross). The thinner header was for the US models probably to comply with noise and emission regulations. But who knows what Duacti did as they often just took what was on the shelf. There may be US Pasos with the bigger header and european Pasos with the smaller one. If there are some european bikes with thinner header and also some with the bigger header diameter it may have been also a change during production. I don`t know. Ian Fallon mentions behind the numbers of the upgrade header "(from frame no. 752124)". I`m not sure what that means.

Antti, what part number does your front header have 0370.84.020 or 0370.84.023 ? As I mentioned I have the 0370.84.020 and the outer diameter is also 40mm. (Fallon mentions the .023 for the kit so what other than the crossing can be different?!)

I`m interested in pictures of the 0370.84.023.

G.

[Tamburinifan]

Are you referring to silencer or header ?

I`m referring to headers, first part from heads, front and rear.
Are they relly different size on an EU 750,
40 mm fr cyl to cross & 35 from rear cyl to cross?!?
Just asking, guess anything is possible.

[Finnpaso]

G: My header is 0370 84 020, so its same, as Yours, or SHOULD be...

I am also wondering that Ian Falloons code now.... Anyway, there have been many wrong numbers/codes/strange things in those times in factory. It was time before EU came...

[paso750]

40 mm from cyl to cross & 35 from rear cyl to cross?!?

ok, understand. No, of course not. The front and rear tubes are both either 35 or 40mm od.

[Tamburinifan]

OK, maybe I misunderstood first post.

Are you referring to silencer or header ?

Just asking about 40 mm dia f 750 as I know f e
750 & 900 M & SS headers aren`t compatible (35-40mm, different stroke)
but the silencers are.
So, Paso seems to differ from other models w 40mm on all 3 models.
God research again, lads.

[paso750]

but the silencers are.

not on a Paso