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 Post subject: Irregular idling Weber
PostPosted: Sun Sep 27, 2015 9:05 pm 
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Joined: Sun Jan 16, 2005 12:00 am
Posts: 257
Location: The Netherlands
model: 750 Paso
year: 1989
Gents, again I can use some advice. In the last couple of weeks I took the paso apart to install hc pistons (1mm squish :mrgreen:), 40mm headers and a lighter flywheel. Also made a few changes on the Weber (44). My setup now is 145 main, 175 ac, 57 idle jets, 34 venturis, stock starter jet, 35 pump jet, stock f27 tubes, float level 43mm and a vacuum pump. It runs ok above 3k rpm and there seems to be no bogging at transition near 5k rpm. I will take the bike to work this week which will be approx 50 kms on the highway. Will see what happens..

Now i have a bit of a challenge on idle. When the bike is on its centerstand and running idle there is not a problem. Reacts well on throttle, especially with the 40% lighter flywheel :thumbup: When moving and aproaching a crossing the bike has to come to a halt. Braking on the brembos and on the engine. Right before a complete stop the clutch goes in.. The rpm will fall back to approx 2k and takes a bit of time goin down to 800 rpm. It needs a moment and goes up to 1200 rpm and stays there. In meantime it runs like cr@p. Maybe misses the power of one cilinder a couple of times. Electrics that recently has been done: new coils, new plugs and new red ngk cables.
Seems to be the Weber. The idle mixture screw is 4,5 turns out. Any less and the symptoms get worse. I tried larger idle jets, but still it needs 4 or 4,5 turns out. Btw it is the dcnf44 112 model..
Any ideas? Float level?
Tx again

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Last edited by Brutus on Mon Sep 28, 2015 4:51 am, edited 2 times in total.

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 Post subject: Re: Inregular idling Weber
PostPosted: Sun Sep 27, 2015 10:01 pm 
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paso grand pooh-bah
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Joined: Tue Jul 29, 2008 9:50 pm
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Location: Hilltown,Pennsylvania
model: 906 Paso
year: 1990
check the needle and seat for leaking, if you are sure it is not leaking try lowering the float a little and do a good sync

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 Post subject: Re: Irregular idling Weber
PostPosted: Mon Sep 28, 2015 4:50 am 
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Joined: Sun Jan 16, 2005 12:00 am
Posts: 257
Location: The Netherlands
model: 750 Paso
year: 1989
tx Higgy, first thing I will look at.
Léon

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 Post subject: Re: Irregular idling Weber
PostPosted: Mon Sep 28, 2015 10:23 am 
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paso grand pooh-bah
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Joined: Sun Jul 18, 2004 12:00 am
Posts: 5418
Location: southern Germany
model: 750 Paso
year: 1987
Leon,

did you calculate the actual compression ratio?
Also while you replaced ignition parts did you check the voltage at the coils and CDI units?
Original silencers & airbox/filter?
What spark plugs are you using?

G.


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 Post subject: Re: Irregular idling Weber
PostPosted: Mon Sep 28, 2015 2:23 pm 
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Joined: Sun Jan 16, 2005 12:00 am
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Location: The Netherlands
model: 750 Paso
year: 1989
Hi Gerard, I have used the original Borgo pistons that came with the first 750paso's. Had it lying around, low milage with matching cilinders. First installed it without the base gasket and measured squish. This wasn't enough and with 0,3mm gaskets I've reached 1mm squish all around for the two cilinders. Compression ratio should be near 1:10.5 and 1:11. Don't have the equipment to measure, but it should be fine.
My paso is the cali type with the digiplex and the single sensor in the alternator cover. Installed two coils of an 916 that were also lying around. Read somewhere they are interchangeable due to the digiplex system. Don't know for certain if I checked voltage on both sides. Will do that soon.
Got two open laser exhaust pipes and the k&n filter (56-1120) on the Weber. I changed the spark plugs from iridium types to normal ones dcpr8e.

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 Post subject: Re: Irregular idling Weber
PostPosted: Mon Sep 28, 2015 4:05 pm 
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paso grand pooh-bah
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Joined: Tue Jul 29, 2008 9:50 pm
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Location: Hilltown,Pennsylvania
model: 906 Paso
year: 1990
remember when you are syncing, use only one bleed screw leave the other closed The ones on the side of the carb not the mixture screws

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Ducati,making mechanics out of riders since 1946
There's no problem so bad that a little fixing can't make it worse! : )
If it ain't broke keep fixin it till it is
88 750
90 906
92 907ie


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 Post subject: Re: Irregular idling Weber
PostPosted: Mon Sep 28, 2015 4:16 pm 
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Joined: Sun Jan 16, 2005 12:00 am
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Location: The Netherlands
model: 750 Paso
year: 1989
Tx Higgy. Normally I use an analog instrument to do this. Now I am considering the transparant tubing with colored fluid that is mentioned in the 906 tuning article. I let you know and post some pics if I can find the time ;)
Léon

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 Post subject: Re: Irregular idling Weber
PostPosted: Mon Sep 28, 2015 6:50 pm 
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Joined: Fri Jul 24, 2015 11:21 am
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Location: Belgium
model: 750 Paso
year: 1989
Hi Léon,

Detail: why didn't you use the iridium spark plugs anymore? :huh:

Frank

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 Post subject: Re: Irregular idling Weber
PostPosted: Mon Sep 28, 2015 7:12 pm 
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Location: The Netherlands
model: 750 Paso
year: 1989
Frank.61 wrote:
Hi Léon,

Detail: why didn't you use the iridium spark plugs anymore? :huh:

Frank


Used them before with the stock pistons CR 1:9. I had to open the gap to get enough spark. I noticed that the original plugs give a brighter spark, so I tried these instead.

Léon

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 Post subject: Re: Irregular idling Weber
PostPosted: Mon Sep 28, 2015 9:18 pm 
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Location: The Netherlands
model: 750 Paso
year: 1989
While I am at it, I would like to replace the needle valve. Can't seem to find part numbers of a Grose Jet that would fit. Right length and same thread. Anyone? Tx.
Léon

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 Post subject: Re: Irregular idling Weber
PostPosted: Mon Sep 28, 2015 9:24 pm 
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paso grand pooh-bah
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Location: Hilltown,Pennsylvania
model: 906 Paso
year: 1990
D & G Valve Manufacturing Co Inc
Valves-wholesale
Address: 8 Mt Vernon St, Stoneham, MA 02180
Phone:(781) 438-1789

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Ducati,making mechanics out of riders since 1946
There's no problem so bad that a little fixing can't make it worse! : )
If it ain't broke keep fixin it till it is
88 750
90 906
92 907ie


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 Post subject: Re: Irregular idling Weber
PostPosted: Tue Sep 29, 2015 9:39 am 
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Joined: Thu Oct 22, 2009 10:38 am
Posts: 247
Location: Mildura ,Australia
model: 750 Paso
year: 1986
Hi Leon , read what I had to say about the idle adjustment in weber what if cheers Jay


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 Post subject: Re: Irregular idling Weber
PostPosted: Tue Sep 29, 2015 11:15 am 
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paso grand pooh-bah
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Joined: Tue Jul 29, 2008 9:50 pm
Posts: 3232
Location: Hilltown,Pennsylvania
model: 906 Paso
year: 1990
http://forums.ducatipaso.org/viewtopic.php?f=1&t=4683&hilit=weber+what+if

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Ducati,making mechanics out of riders since 1946
There's no problem so bad that a little fixing can't make it worse! : )
If it ain't broke keep fixin it till it is
88 750
90 906
92 907ie


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 Post subject: Re: Irregular idling Weber
PostPosted: Thu Oct 01, 2015 6:07 pm 
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Joined: Sun Jan 16, 2005 12:00 am
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Location: The Netherlands
model: 750 Paso
year: 1989
Gents, tx for the replies. Higgy, I can't find any mailadres or website of this supplier. Is it possible to have an article number or such, so I can find it here in Europe..? Need one in a couple of days if possible. Found one on a maserati site, but they will charge $40usd for shipping. No way I'm paying this amount for something that'll be shipped for perhaps $4usd..

https://www.maseratinet.com/pc-22190-380-grose-jet-needle-valve.aspx

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 Post subject: Re: Irregular idling Weber
PostPosted: Fri Oct 02, 2015 6:03 am 
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Location: The Netherlands
model: 750 Paso
year: 1989
Maybe some dimensions, if possible..? Length jet, diameter of the thread and the pitch..?

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