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 Post subject: Re: Observations and questions, continued
PostPosted: Wed Dec 16, 2015 6:39 am 
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Joined: Thu Jul 09, 2015 12:59 pm
Posts: 25
Location: USA
model: 750 Paso
year: 1988
I figured it out!

Now I understand what the relay does, although the CDI boxes are still a mystery. I recreated the original wiring: front coil orange wires are the lead from the relay, lead from the CDI box, and shunt to rear coil; rear coil gets the second CDI box lead and the shunt.

Started right up, stronger than ever! Tomorrow, a ride!

Thanks again, especially for your patience with nincompoops. Better to figure it out for ourselves (with assistance..)!!!


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 Post subject: Re: Observations and questions, continued
PostPosted: Sat Dec 19, 2015 10:43 am 
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paso grand pooh-bah
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Joined: Sun Jul 18, 2004 12:00 am
Posts: 5234
Location: southern Germany
model: 750 Paso
year: 1987
sorry was a bit busy these past days. Good that you figured it out. I`ll see if I can correct the files over the christmas holidays.


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 Post subject: Re: Observations and questions, continued
PostPosted: Mon Dec 21, 2015 2:54 am 
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Joined: Thu Jul 09, 2015 12:59 pm
Posts: 25
Location: USA
model: 750 Paso
year: 1988
Thanks G,

Went for a glorious 60 mile ride this afternoon to a German smokehouse to pick up fixings for Xmas dinner. Aside from the now officially leaking clutch slave o-ring (clutch worked perfectly all the way home!), my only niggling complaint is an intermittent miss. I tried to understand what might trigger it, and was without a clue. It sounds like a sneeze, clearly a loss of power, that happens at any time I am not accelerating. No specific rpm, but possibly more often with gently acceleration, or just coming off the throttle.

I'm starting to feel confident that I will not be stranded if I go for a long ride, a good feeling. However, we all have to ante up for those good feelings, like with once again rebuilding the slave cylinder!

Thanks much!


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 Post subject: Re: Observations and questions, continued
PostPosted: Mon Dec 21, 2015 12:25 pm 
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paso grand pooh-bah
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Joined: Tue Jul 29, 2008 9:50 pm
Posts: 3182
Location: Hilltown,Pennsylvania
model: 906 Paso
year: 1990
check the connections at the bottom of the ignition switch and the grounds everywhere. Also make sure you have solid contact at the ignition control unit

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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: Observations and questions, continued
PostPosted: Wed Jan 06, 2016 12:36 am 
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Joined: Thu Jul 09, 2015 12:59 pm
Posts: 25
Location: USA
model: 750 Paso
year: 1988
Higgy, just wanted to thank you for the incredible Weber doc that you and Romus put together on the 906 list (thought I'd go exploring the rest of ducatipaso.org and found it). Learned more about fluid dynamics and the Weber than I ever thought I wanted to know.

Implemented your jetting recommendations after checking all my connections as you suggested, including switching the Kokusan boxes front to rear. Connections were good, but no improvement with the hesitation/'sneezing'. However, the jetting 'steps', as well as the float level alterations did markedly improve performance. But still the hesitation remained, until I put the choke on just a slight bit - it ran perfectly (although the idle was high, obviously). What is that a symptom of, and what do I need to do to correct it?

Happy New Year


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 Post subject: Re: Observations and questions, continued
PostPosted: Wed Jan 06, 2016 2:07 am 
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paso grand pooh-bah
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Joined: Tue Jul 29, 2008 9:50 pm
Posts: 3182
Location: Hilltown,Pennsylvania
model: 906 Paso
year: 1990
generally better running with a small choke setting is an indication of air leaks at the throttle plates or a general lean jetting across the board.

_________________
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: Observations and questions, continued
PostPosted: Sun Feb 14, 2016 7:57 pm 
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Joined: Thu Jul 09, 2015 12:59 pm
Posts: 25
Location: USA
model: 750 Paso
year: 1988
Thanks once again for helpful advice.

Higgy, air leaks at throttle body: same opinion of my local foreign car mechanic, old ferraris etc. his usual pass time. In searching the discussion for air leaks, etc., and how to drill out idle air mixture screw covers (which I have never done), happened upon discussions of removal of the airbox interface between the carb body and trumpets. Not having wanted to destroy my airbox, I simply mounted by new air cleaner on top of the carb body... Another lesson learned...destroy away I did.

Too cold to ride here (-3 degrees F), but after mounting the piece of the airbox that smooths the passage of air, no more stumbling.

Also, bought a Venhill clutch line and new throwout bearing, resulting in a working clutch, and easy-to-find neutral.


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 Post subject: Re: Observations and questions, continued
PostPosted: Sun Feb 14, 2016 11:15 pm 
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paso grand pooh-bah
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Joined: Tue Jul 29, 2008 9:50 pm
Posts: 3182
Location: Hilltown,Pennsylvania
model: 906 Paso
year: 1990
yup many older Italian makes used a version of the DCNF. I have sold more than a few for the Merek/Maserati

_________________
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: Observations and questions, continued
PostPosted: Wed Mar 09, 2016 3:27 am 
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Joined: Thu Jul 09, 2015 12:59 pm
Posts: 25
Location: USA
model: 750 Paso
year: 1988
Hello,

Well, I fooled myself thinking the stumble was eliminated. Finally had a chance to do more work and here is what I found:
Existing conditions: Rear plug black and oily. Front plug perfect brown/grey coloring.

Tested spark (NKG DR8EA) with both plugs at both cylinders by grounding plug and cranking. Equivalent spark (strong blue/purple) at both cylinders; plugs gapped at 0.7 mm.

Took off the welch caps (or whatever they are called) and gained access to the idle mixture and air bypass screws (existing conditions):
Rear cylinder, IMS = 5.5 turns out; ABS = zero turns out. Front cylinder, IMS = 4.75 turns out; ABS = many turns out (5 or 6).

Started the tune with IMS at 2 turns out, and ABS at zero. Tank off (chicken baster fuel reservoir). Idle screw at 0.5 turns after touch. Ran for 5 minutes with choke on and babying it to keep it running. With a strong light on, I could see that at every miss and die, cloud of gas vapor came out of starting device (choke). Also, I noticed that I was missing a screw in the middle rear of the manifold plate just below the carb base. (Yes, Higgy!) Plugged hole with screw.

Raised idle additional half turn until it would stay running.

Took off brass caps for vacuum takeoffs, and added brass pipes for my elecronic carb synchronizer. Needed to unscrew IMS's by 1.5 additional turns to keep it running. Played with screws until relatively balanced on sync tool, almost achieving balance. Opened the front ABS by ~2 turns to achieve what the sync tool said was balance.

Results were not good. Still lean, as things smooth out with a little choke on.

No additional jet changes from my last post.

Thanks. :wacko:


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 Post subject: Re: Observations and questions, continued
PostPosted: Fri Mar 11, 2016 4:14 pm 
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paso grand pooh-bah
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Joined: Sun Aug 01, 2004 12:00 am
Posts: 1092
Location: siena, italy
model: 750 Paso
year: 1988
It's unuseful tune the carb at idle.
When you ride, you alwais handle throttleso you'd rather to balance @2000 rpm before setting idle screws.
Unluckly the only way to do such is twist the throttle axle in order to make both bodies run sincronized. Don't use tools, only fingers to force the axle!

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have a nice ride, Nicola

Black "DUKE" 751582
ex...Red "smooth" 753349 :-(


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 Post subject: Re: Observations and questions, continued
PostPosted: Tue Mar 15, 2016 3:34 am 
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Joined: Thu Jul 09, 2015 12:59 pm
Posts: 25
Location: USA
model: 750 Paso
year: 1988
Thanks, Nicola.

Your suggestion did improve things, as did a vigorous ride to start the tuning process. Adjustments of the jets had a noticeable effect at 2K rpm, where the same at 1K seemed to have no effect. The results were dramatic, that I enjoyed for my entire 175 mile ride. Coming off idle, accelerating, cruising at 80, back roads and interstate were all pleasurable.

Time to put this thread to bed. Now I have to fix the oil leak that started at the temperature sensor!


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 Post subject: Re: Observations and questions, continued
PostPosted: Tue Mar 15, 2016 7:47 am 
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paso grand pooh-bah
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Joined: Sun Aug 01, 2004 12:00 am
Posts: 1092
Location: siena, italy
model: 750 Paso
year: 1988
;)

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have a nice ride, Nicola

Black "DUKE" 751582
ex...Red "smooth" 753349 :-(


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