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 Post subject: Observations and questions, continued
PostPosted: Mon Nov 30, 2015 4:07 am 
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Joined: Thu Jul 09, 2015 12:59 pm
Posts: 25
Location: USA
model: 750 Paso
year: 1988
Since my last post, I have put about 150 miles on my Paso, which were most enjoyable except for a couple of nagging problems related to the performance, and the clutch. As I mentioned previously, the carb was completely rebuilt, with jetting redone per JayH's experiments. And the clutch was taken apart, cleaned, new slave o-ring installed, and new master/reservoir installed. First, the carburetor:

In an effort to eliminate what sounds like a sneeze (miss? backfire?) with associated hiccup in performance, irregular, at any and all throttle positions, I put my stock air correctors back on. This did not eliminate the problem, but did make it less severe, meaning it happened less often. My thinking was that this sneeze might be a lean condition. This may be a correct assumption, as performance with the stock air correctors seems to be more sluggish in the 3000-5000 range.

Given that this sneeze happens at any throttle position, could this be an electrical miss? It does seem to happen most often at steady speed or at deceleration, not during acceleration. Also when starting off-I seem to have to rev it higher than I would expect to keep it from dying out as I let out the clutch. I have stock coils, wires, all electrics; and new spark plugs gapped to 0.6mm.

The clutch:
It is not fully disengaging, where the bike gives little lurches when stopped in gear waiting to accelerate. I also have to be very exact with my rpm on shifting, so that I can smoothly engage the next gear. Shifting is smooth, no noise or roughness with the transmission. Evidence points to the o-ring I purchased as not being brake-fluid resistant, as there is black coloration in the new brake fluid. I found this as I re-bled the system after replacing the master cylinder/reservoir, and making sure that the clutch cover bore was clean, and the slave rotated well in it's bearing. Since my ride yesterday, I have not checked to see if in fact I am spraying brake fluid onto my clutch disks. I also have yet to examine if the clutch disks were installed in the recommended order per the FAQ's; I just reinstalled them in the order I found them when I cleaned that area up. This is my first experience with a Duc hydraulic clutch, so I need to be educated as to what expectations for this system should be. There are ~13,500 miles on the odo.

Lights:
My lights (taillight most noticeable) pulses at idle...goes away with higher revs. Problem? If so, correction?

Fork:
Is the fork meant to be pressurized through the air valves at the filler caps?

Thanks much for your continued assistance.


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 Post subject: Re: Observations and questions, continued
PostPosted: Mon Nov 30, 2015 9:40 am 
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paso grand pooh-bah
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Location: Scotland
model: 907 I.E.
year: 1994
I can only comment on the lights and forks as I've no experience with the Weber carb not that clutch arrangement.

I wouldn't worry about the pulsing lights at idle, many bikes do it to some extent. It is because at idle speed the alternator frequency is very low and the regulator output voltage drops between the AC voltage peaks. At higher speeds the frequency is higher and the ripple voltage smooths out. When I had an ST4s used to see it on the LCD screen for the fuel and temperature display and I wondered if this would affect the ECU so I considered fitting a capacitor across the battery to smooth out the ripple. I never did get round to it and nothing failed as a result.

The forks shouldn't be pressurised.

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2017 Supersport 939
2015 Scrambler Classic
1982 Pantah 500SL


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 Post subject: Re: Observations and questions, continued
PostPosted: Mon Nov 30, 2015 10:46 am 
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paso grand pooh-bah
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Joined: Sun Jul 18, 2004 12:00 am
Posts: 5219
Location: southern Germany
model: 750 Paso
year: 1987
as Derek said some pulsating of the lights is normal. It could be though that what you`re experiencing with the lights is connected to what you notice with your ignition. Do check the voltage at the headlights, the coils and CDI units and check the FAQs for the wiring mod.

When you remove the clutch discs do measure if they are still above minimum thickness. Also when the springs are removed verify that the pressure plate (clutch control disc) moves in and out freely.

The valve is just to release pressure after rebuilding the fork and installing it.


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 Post subject: Re: Observations and questions, continued
PostPosted: Mon Nov 30, 2015 3:54 pm 
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paso grand pooh-bah
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Location: Scotland
model: 907 I.E.
year: 1994
Yes, if the lights pulse along with the indicators then it's due to high resistance at the ignition switch contacts. It is very common and as G says check out the wiring mod in the FAQ.

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2017 Supersport 939
2015 Scrambler Classic
1982 Pantah 500SL


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 Post subject: Re: Observations and questions, continued
PostPosted: Mon Nov 30, 2015 5:31 pm 
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paso grand pooh-bah
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Joined: Tue Jul 29, 2008 9:50 pm
Posts: 3185
Location: Hilltown,Pennsylvania
model: 906 Paso
year: 1990
:?
Pulsing of any lighting is not normal and always is indicative of an elecrical issue

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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
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92 907ie


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 Post subject: Re: Observations and questions, continued
PostPosted: Tue Dec 01, 2015 1:14 pm 
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Joined: Mon Apr 03, 2006 12:00 am
Posts: 371
Location: Northampton UK
model: 907 I.E.
year: 1993
Higgy on a 750 ?

Its only a single phase generator isn't it in which case you have a big gap between the pulses in the rectified output - you'd expect some pulsing surely - you can see it on a 'scope so why not in the lights


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 Post subject: Re: Observations and questions, continued
PostPosted: Tue Dec 01, 2015 9:33 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
Many of us experienced troubles about loss of performance @5000 rpm and someone solved modifying the cross in the exaust pipe (making it wider, There should be some post about it). I also felt this trouble but I didn't try nothing to debug but balancing correctly and installing a more recent pair of "emulsion
" tubes in the carburetteur (I mean the small bronze pipes between main jet and air corrector). They have a F letter and a number marked. Newer releases have higher marks.

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


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 Post subject: Re: Observations and questions, continued
PostPosted: Tue Dec 01, 2015 11:23 pm 
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paso grand pooh-bah
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Joined: Tue Jul 29, 2008 9:50 pm
Posts: 3185
Location: Hilltown,Pennsylvania
model: 906 Paso
year: 1990
All three use the same basic stator/regulator setup. the only difference is the way the stators are wired. Some are a single wire winding, others are two wire windings with a common pole. I do realize if you have an older regulator you may experience an AC leak at 60 Hz that some folks are sensitive to. All that being said pulsing of headlights due to turn signals or low rpm is indicative of a wiring issue. Poor ground(#1), high resistance in the wiring or connectors(#2) or just poor design(as in our case on the older models) All this can be resolved with an updated wiring with the addition of relays to unload our very hard to find and overloaded ignition switches. Even the 907 can benefit from updated wiring.
Once the wiring issues have been resolved it is also beneficial to add a more modern regulator as in Shindengen FH020AA, SH775 and now the SH847 Upgrade Kits which will add many years of life to our stators, especially the new non shunt type regulator.
On my 907ie which has left me stranded more than once I had a custom stator wired up straight to the regulator with no connectors in between and a larger grade of wire. I also upgraded the fuse box and added a Mosfett regulator as in Shindengren. I no longer have any issues whatsoever. In fact I get a minimum of 14 volts across the battery within 1 min of starting regardless of the temperature at startup. Even with everything on I get at the very least 14 volts across the battery once the regulator is warmed up. I had planned to add a fan to the regulator heat sink but it works so reliably I have yet to install it and it sits at the rear of the bike over the tire. :beer: :beer: :beer:

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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 Dec 02, 2015 1:55 am 
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Joined: Thu Jul 09, 2015 12:59 pm
Posts: 25
Location: USA
model: 750 Paso
year: 1988
Everyone,

Thanks much for your comments and advice. I will start implementing solutions, and report my results as I get things done. :thumbup:


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 Post subject: Re: Observations and questions, continued
PostPosted: Wed Dec 02, 2015 6:06 am 
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paso grand pooh-bah
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Joined: Sat Sep 03, 2005 12:00 am
Posts: 1318
Location: SF Bay Area
model: 750 Sport
year: 1990
As mentioned, fork should not be pressurized, but the air volume in the fork does act as a progressive spring. So, if you want your fork to be more progressive, reduce the air volume by adding more oil. That is why the oil measurement is done by distance from the top of the tube, and not cc of volume.

the air valve is there to bleed off the excess that builds up from time to time.

Cheers, Phil

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1990 750 Sport x2-Rosso Blanko (900ss copy) & Nuovo Nudo (Scrambler project)
1991 907 -mostly stock
2002 ST4s - Lots of mods.


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 Post subject: Re: Observations and questions, continued
PostPosted: Sun Dec 06, 2015 1:12 am 
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Joined: Sat Aug 11, 2012 5:23 pm
Posts: 11
Location: USA
model: 750 Paso
year: 1988
Experience with my Paso and a friend's Elefant indicates insufficient clutch slave piston travel to prevent drag, as evidenced primarily by difficulty selecting neutral. He installed a braided steel hose. I made a 6mm spacer for the clutch perch which gives the lever more travel. This solved our clutch drag problems. You can also try thinner grips and experimenting with the lever adjustment screw. Beware: Screwing it in too far can prevent the refill hole from opening in the master cylinder.

Clint


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 Post subject: Re: Observations and questions, continued
PostPosted: Tue Dec 15, 2015 12:50 am 
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Joined: Thu Jul 09, 2015 12:59 pm
Posts: 25
Location: USA
model: 750 Paso
year: 1988
Hello,

This weekend I had a chance to complete some to the things on my list: thoroughly cleaned the clutch slave mushroom and throwout bearing, eliminating all notchiness. Repacked the clutch correctly per the FAQ's. Both seem to have improved clutch feel and actuation, at least on the centerstand.. My questions regard the wiring mods.

I completed the starter relay install without issue; headlight and gauges are noticeably brighter. However, the coil wiring mod does have issues. The instructions say to remove the orange wires from the coils, "use one to switch the relay", and tape one up, which I did. Pictures and diagrams seem to show one wire to each coil, which I assumed were the arms of the "Y" subharness.

My front coil had three orange wires: one from the kill switch, one from the Kokusan box under the seat, and one the shunt over to the other coil. My rear coil had the other wire from under the seat and the other end of the shunt.

I made up the Y harness and cut the other wires, taping the two from under the seat up unused. The kill switch wire went to the #86 terminal; ground to #85; Y to #87: and the 10A fused power supply to the #30 terminal. Arms of the Y were connected to the coils.

This resulted in no spark to the plugs. Realizing that I should have connected the wires from under the seat, I redid the harness so that those two wires went to each of their respective coils.

Jump in anywhere to call me an idiot. I was never good at electricity.

Again trying to start gave me nothing, then a little bark. As I did not want to fill the garage with exhaust, I rolled her outside (11 PM), and tried again.

One COLOSSAL backfire later and I gave up, hoping I didn't do any irreparable damage to anything. My neighbors I can deal with....

What did I do wrong?

Thanks in advance.


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 Post subject: Re: Observations and questions, continued
PostPosted: Tue Dec 15, 2015 9:49 am 
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paso grand pooh-bah
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Joined: Sun Jul 18, 2004 12:00 am
Posts: 5219
Location: southern Germany
model: 750 Paso
year: 1987
if you do the simple coil wiring mod no wires need to be cut.
If you look at the original wiring diagram the power comes from the kill switch to one coil and splits there to one CDI unit and the other coil. From there another orange wire goes to its CDI unit.
If you disconnect the connectors from both coils isolate one and connect the remaining connector to switch the relay everything will work as before.
What did you cut? Is it possible the power supply to one CDI unit was cut (or to both)?

G.


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 Post subject: Re: Observations and questions, continued
PostPosted: Tue Dec 15, 2015 11:08 pm 
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paso grand pooh-bah
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Joined: Sat Sep 03, 2005 12:00 am
Posts: 1318
Location: SF Bay Area
model: 750 Sport
year: 1990
Sounds like you switched the leads. - maybe. Wrong signal to the coil. Front cylinder signal to rear cylinder coil?

Phil

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1990 750 Sport x2-Rosso Blanko (900ss copy) & Nuovo Nudo (Scrambler project)
1991 907 -mostly stock
2002 ST4s - Lots of mods.


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 Post subject: Re: Observations and questions, continued
PostPosted: Wed Dec 16, 2015 5:09 am 
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Joined: Thu Jul 09, 2015 12:59 pm
Posts: 25
Location: USA
model: 750 Paso
year: 1988
Thanks, G.

Looking back for the simple coil mod, I came across this from 2012:
<<<<<<<<<<<<<<<
So step two would be adding a relay which is simple. Get a standard 12V relay with 4 contact pins.
1. Find a position to mount the relay
2. Disconnect the 12V feed from each coil (isolate one end), connect the remaining end to pin 86 of the relay
3. Make a new Y cable to connect the relay output (pin marked 87) to the two coils
4. connect one relay pin to ground (85)
5. run a cable from the battery (with an inline fuse) to the relay (30)
That`s it.
<<<<<<<<<<<<<<<

You describe the wiring layout perfectly. Correct me if I am wrong, but in your response to me you say "If you disconnect the connectors from both coils isolate one and connect the remaining connector to switch the relay everything will work as before." I assume I should be connecting the connector that goes to the kill switch, front CDI box, and shunt, to the relay. What happens to the other orange wire that goes to the rear CDI box?

I cut both orange wires between the coils and CDI boxes, and the orange wire from the kill switch. Kill switch went to terminal 86, Y to 87. When I had no spark, reconnected respective CDI orange wires to their respective coils.

Thanks for your patience.


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