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 Post subject: 906 exhaust
PostPosted: Wed Dec 05, 2007 1:30 am 
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paso grand pooh-bah
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Location: Newzealand
model: 906 Paso
year: 1990
I have been eyeing this cross shaped junction thing in the exhaust with some suspicion . Can any one tell me if this thing robs as much power as it looks as if it might ?Is it worth making up a "straight thru " system , with a cross over pipe ?

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 Post subject: Re: 906 exhaust
PostPosted: Wed Dec 05, 2007 6:32 am 
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paso grand pooh-bah
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DONT take that cross junction away!!! It helps to have better low/mid rpm torque! Its JUST for taking better performance from V-2 engine. U can see such also in very many Guzzis. Its very important equipment, so dot take it away.... :smoke:

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 Post subject: Re: 906 exhaust
PostPosted: Wed Dec 05, 2007 11:59 am 
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paso grand pooh-bah
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Location: Hudson Valley, NY
model: 750 Paso
year: 1988
It does restrict the the flow and there have been spaghetti systems from Ducati in the past but I doubt they fit the Paso. You can cut the box open and remove the square section that is welded inside, This is said to improve flow. Here is a picture of a spaghetti system:

Image

I know of a welder that can make this header and it costs about $1600 if what I was told is correct.

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 Post subject: Re: 906 exhaust
PostPosted: Wed Dec 05, 2007 1:04 pm 
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paso grand pooh-bah
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Location: southern Germany
model: 750 Paso
year: 1987
The ideal in the header cross would be to have it in the same diameter as the rest of the tubes just like this Termignioni system
Image

There are some guys that drive around with completely open header crosses but I don`t think that is good. The exhaust gas streams of both cylinders meet there and to my understanding there should be something leading the streams to the side or at least preventing that the streams directly hit each other causing turbulences.

I had my own middle part totally removed and replaced by 2 open halves. Then they were cut open and a machined new cross was welded in. (the cross has curved flanks, it`s not just a square)
Image

There are no dynoruns that I know of so this is mainly theoretical and experimental.

G.

PS: it`s not chromed but glasbead blasted and then nickel plated
Sidenote: the screws you see on the header normally are totally rusted and hardly removeable as they are made of steel. Meanwhile Ducati sells them made of stainless steel for little money.


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 Post subject: Re: 906 exhaust
PostPosted: Wed Dec 05, 2007 3:05 pm 
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paso grand pooh-bah
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Jon,
you don`t happen know who the manufacturer is of the chain with the golden links (in your pic) ?!

G.


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 Post subject: Re: 906 exhaust
PostPosted: Wed Dec 05, 2007 5:46 pm 
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paso grand pooh-bah
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paso750 wrote:
Jon,
you don`t happen know who the manufacturer is of the chain with the golden links (in your pic) ?!

G.


I have a gold chain it's a DID if I recall.

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 Post subject: Re: 906 exhaust
PostPosted: Wed Dec 05, 2007 7:55 pm 
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Location: Hudson Valley, NY
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paso750 wrote:
Jon,
you don`t happen know who the manufacturer is of the chain with the golden links (in your pic) ?!


I think all major makers can put the gold lines on. It's a very common replacement here in the USA.

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 Post subject: Re: 906 exhaust
PostPosted: Wed Dec 05, 2007 8:07 pm 
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paso grand pooh-bah
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I have used such "golden" linked chains very long time, DID is manuafacturer. :smoke:

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 Post subject: Re: 906 exhaust
PostPosted: Thu Dec 06, 2007 2:11 am 
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Location: Gothenburg, SWEDEN
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Quote:
There are no dynoruns that I know of so this is mainly theoretical and experimental.

Did this on my Monster and buttDyno felt OK, I also have no verification of
if it is good.
Someone said who seems knowledgeable that it helps at low revs and
is bad at high.
Exhaust system w/o crossover is in my experience bad on a mostly
unmodified engine.

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 Post subject: Re: 906 exhaust
PostPosted: Thu Dec 06, 2007 10:04 am 
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paso grand pooh-bah
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Location: southern Germany
model: 750 Paso
year: 1987
Quote:
Someone said who seems knowledgeable that it helps at low revs and
is bad at high.

I would think it`s vice versa. In whatever forum you look there is no proof of any advantage specially on an original engine. Not even a spaghetti header does much on an original bike w/o sport filter, open cans, tuned carbs etc. All agree though that the worst thing you can do is to totally remove the cross, meaning to just cut it out and weld a cover on both sides w/o anything that guides the exhaust streams. In fact the exhaust streams directly hitting each other could have a negative effect on performance and due to the worse flow towards the exhaust the exhaust gas and the header could heat up even more and on the longrun damage the exhaust valves.
Howfar the original cross is really restrictive or not can be discussed. If you look at it each header tube splits in 2 halves and 2 halves make 1. If the split halves are in fact not smaller than the half of the headertubes I`d say it`s the best solution for an original bike and it should be left as it is. What a modified header cross definetely does is it makes it slightely louder (probably giving the effect to think there is more power)

Image

G.


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 Post subject: Re: 906 exhaust
PostPosted: Sat Oct 24, 2015 1:42 pm 
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paso grand pooh-bah
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Location: Hilltown,Pennsylvania
model: 906 Paso
year: 1990
http://www.bikeboy.org/888st4ex.html


4 valve info,can't say if its relevant

a little more http://www.bikeboy.org/900monsterexhaust.html

http://www.bikeboy.org/st2hicomp.html

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 Post subject: Re: 906 exhaust
PostPosted: Sun Oct 25, 2015 9:51 am 
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paso grand pooh-bah
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I modded the X-over section of my 900SS some 14 years or so ago, the same as this one -
Image
I can't honestly say if it made any difference but I did subsequently read from a well known tuner, Doug Lofgren possibly, that there was little point in this mod because by far the biggest restriction was the inlet ports, which have a very poor shape.

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 Post subject: Re: 906 exhaust
PostPosted: Sun Oct 25, 2015 11:24 am 
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paso grand pooh-bah
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Location: siena, italy
model: 750 Paso
year: 1988
Jon, your first pic isunavailable. Maybe it was something like this?
Image

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 Post subject: Re: 906 exhaust
PostPosted: Sun Oct 25, 2015 12:29 pm 
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paso grand pooh-bah
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Location: Hilltown,Pennsylvania
model: 906 Paso
year: 1990
I think the general consensus is it has some advantage on carbed engines not so much with injected without a lot of additional work

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If it ain't broke keep fixin it till it is
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