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 Post subject: Ducati 900 Supersport 1989 is going back to Weber
PostPosted: Thu Sep 03, 2015 11:08 am 
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Joined: Fri Aug 21, 2015 8:26 pm
Posts: 6
Location: Lithuania
model: 900 SS
year: 1989
Hello to everyone,
I am a new owner of Ducati 900 Supersport 1989. This is my first Ducati. I have read this forum a lot before buying this motorcycle, but now I can't find answers to my questions, that's why I have created new post.
This is my motorcycle:
Image
It came with Dellorto carbs PHM40 and I want to covert back to Weber 44 DCNF. So I have bought Weber "44 DCNF-118 9J" from Germany it came with airbox and intake manifolds:
Image
Image
When I have attached these manifold to the engine and tried to fit Weber manifold, it looked not straight, but turned to right side:
Image
Image
I want to ask if it is normal when fitting Weber or the manifolds that came with Weber carb are not original and from another bike and angles are wrong? :)


Last edited by slepsnys on Thu Sep 03, 2015 2:45 pm, edited 1 time in total.

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 Post subject: Re: Ducati 900 Supersport 1989 is going back to Weber
PostPosted: Thu Sep 03, 2015 11:53 am 
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paso grand pooh-bah
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Joined: Sun Jul 18, 2004 12:00 am
Posts: 5061
Location: southern Germany
model: 750 Paso
year: 1987
Hi, the links to your pictures don`t work but did you try to swap the carb manifolds? They are not identical (according to the part numbers).


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 Post subject: Re: Ducati 900 Supersport 1989 is going back to Weber
PostPosted: Thu Sep 03, 2015 4:21 pm 
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Joined: Fri Aug 21, 2015 8:26 pm
Posts: 6
Location: Lithuania
model: 900 SS
year: 1989
I have updated links, so now they should work. I have tried to swap manifolds and result is same, so both manifolds are identical.


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 Post subject: Re: Ducati 900 Supersport 1989 is going back to Weber
PostPosted: Thu Sep 03, 2015 6:12 pm 
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paso grand pooh-bah
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Joined: Sun Jul 18, 2004 12:00 am
Posts: 5061
Location: southern Germany
model: 750 Paso
year: 1987
install the rubber boots. They have an impact on the carbs position. (and eventually try to swap the manifolds again;)


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 Post subject: Re: Ducati 900 Supersport 1989 is going back to Weber
PostPosted: Thu Sep 03, 2015 7:35 pm 
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Joined: Fri Aug 21, 2015 8:26 pm
Posts: 6
Location: Lithuania
model: 900 SS
year: 1989
So, to answer my question, these manifolds are right for Weber carb?


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 Post subject: Re: Ducati 900 Supersport 1989 is going back to Weber
PostPosted: Fri Sep 04, 2015 8:12 am 
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paso grand pooh-bah
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Joined: Sun Jul 18, 2004 12:00 am
Posts: 5061
Location: southern Germany
model: 750 Paso
year: 1987
Yes those are Weber manifolds.

It`s interesting looking at the parts catalogues (unfortunately we don`t have one for the 900SS). The vertical and horizontal carb manifold have the same part numbers on the P750 and the 750S (037098780). On the 750S tho there exist two types, hence two part numbers (037098780 & 037098783). The 906 uses the 037098783 for the horizontal cylinder and a 13710021A for the vertical one. 13710021A is the manifold that the 907ie uses on both cylinders.
Maybe the manifolds for the 900 engine are the same on both cylinders and just one part number was superseded.


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 Post subject: Re: Ducati 900 Supersport 1989 is going back to Weber
PostPosted: Fri Sep 04, 2015 11:33 pm 
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paso grand pooh-bah
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Joined: Wed Dec 05, 2007 12:35 am
Posts: 1528
Location: Newzealand
model: 906 Paso
year: 1990
I seem to recall having a similar issue with my 906 :)

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 Post subject: Re: Ducati 900 Supersport 1989 is going back to Weber
PostPosted: Sat Sep 05, 2015 7:29 am 
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Joined: Fri Aug 21, 2015 8:26 pm
Posts: 6
Location: Lithuania
model: 900 SS
year: 1989
To: Mc tool
And what You have done to resolve this issue? Fitted other manifolds which where straight or adjusted this issue it with rubber boots?


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 Post subject: Re: Ducati 900 Supersport 1989 is going back to Weber
PostPosted: Sun Sep 06, 2015 3:57 am 
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paso grand pooh-bah
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Location: Newzealand
model: 906 Paso
year: 1990
Twas a while ago now but Im pretty sure that the two intake manifolds are different ,but not by much so it aint immediately obvious .Being Ducati , its a bit half arsed and the carb more than likely wont line up perfectly flat and square , which is probly why its hidden under the tank :) If you put the whole lot together and leave the hose clamps loose it may be possible to improve things by rotating the rubber sleeves , or even swapping them around . Sometimes the rubber deforms over time and if you pull em to bits they have to go together exactly ( the same rubber the same way up on the same manifold and oriented the same way ) the way they came apart or they will look wonky

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 Post subject: Re: Ducati 900 Supersport 1989 is going back to Weber
PostPosted: Sun Sep 06, 2015 6:56 am 
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Joined: Mon Dec 15, 2014 11:05 am
Posts: 92
Location: Sleepy leafy South Birmingham UK
model: 750 Paso
year: 1987
Hi slepsnys and welcome to the forum.

That's a nice looking bike you have there, but why do you want to put it back to the single Weber ?

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 Post subject: Re: Ducati 900 Supersport 1989 is going back to Weber
PostPosted: Sun Sep 06, 2015 8:58 am 
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Joined: Fri Aug 21, 2015 8:26 pm
Posts: 6
Location: Lithuania
model: 900 SS
year: 1989
Thank You.

I want to put Weber back because I want bike to be in original condition as possible with its unique automotive carburateur.
To begin with when I got the bike Dellorto PHM40 NS ans PHM40 ND has issues, they where flooding the engine, leaking. I have looked in to these carbs and noticed that according to Dellorto book they where suited for two stroke engine, because of atomizers surround shape (oval is cut).
Image
So I have decided to go back to Weber. I have read Higgy and Romus post about Weber and their posts convinced me that 900cc Ducati engine can work good on Weber with 4.5 aux venturi and apropriate jetting.


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 Post subject: Re: Ducati 900 Supersport 1989 is going back to Weber
PostPosted: Sun Sep 06, 2015 8:23 pm 
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Joined: Mon Dec 15, 2014 11:05 am
Posts: 92
Location: Sleepy leafy South Birmingham UK
model: 750 Paso
year: 1987
Ok thanks for the explanation. I understand now.

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 Post subject: Re: Ducati 900 Supersport 1989 is going back to Weber
PostPosted: Tue Sep 08, 2015 11:05 am 
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Joined: Fri May 02, 2014 10:08 pm
Posts: 29
Location: Australia
model: 750 Sport
year: 1988
Hi Slepsyns,

I also persisted with the dcnf 44 on my 750 Sport and fitted 4.5 aux venturis with larger jets which helped improve the bike on lower end performance. I'm much happier with the riding experience and nothing quite beats the sound of a weber Ducati! It really does sound incredible. Good choice reverting to original.

As for your problem, the manifolds and carb do need a little bit of care moving into position once the rubber boots are on.

All the best.


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 Post subject: Re: Ducati 900 Supersport 1989 is going back to Weber
PostPosted: Tue Sep 15, 2015 2:33 pm 
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Joined: Fri Aug 21, 2015 8:26 pm
Posts: 6
Location: Lithuania
model: 900 SS
year: 1989
Today I have received 4.5 aux venturi for Weber. Weber number is 71107 or 71107450, because they are 4.5 in catalog they where marked as DCNF40, not DCNF44. They are different finish than original, it is very rough and without 4.5 marking, so I have polished one venturi, this is a comparison photos. On left is polished and on right isn't.
Image
Image
This 4.5 venturi is different inside than original 3.5, it has thicker walls.
Image
Original 3.5 venturi:
Image
New 4.5 venturi top:
Image
New 4.5 venturi bottom:
Image
So my question would be if I have bought the appropriate 4.5 venturi for DCNF44? :)


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 Post subject: Re: Ducati 900 Supersport 1989 is going back to Weber
PostPosted: Wed Sep 23, 2015 12:40 pm 
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Joined: Fri May 02, 2014 10:08 pm
Posts: 29
Location: Australia
model: 750 Sport
year: 1988
They look the same as what I installed recently.

I didn't polish mine either and it performs fine.


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