rich running

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themoudie
Posts: 649
Joined: Sat Jun 14, 2014 12:44 am
Location: Scotland

Re: rich running

Postby themoudie » Tue Jun 08, 2021 9:13 am

May I just add here Alex that you are not the only one with revving faults. A Moto Morini 125H that I have starts and ticks over beautifully, then revs freely once warmed up. But, since fitting a "VESPA" Ducati Electronicer transducer, as the original wouldn't advance. On this engine advance is 36°BTDC @6,000rpm.It now, after a 3 to 4 mile run, develops a horrendous bout of misfiring and failure to respond to the throttle, before clearing it's throat, usually with some monumental backfires and then continues the run (30 to 40 miles) as if nothing is wrong!?

The carb is a VHB 24 S and has a new needle and needle jet and all as per factory spec. The ignition is similar to that of the Ducati, in that there is a separate coil on the alternator for the EI and the trigger is on the adjacent stator pole. All of the tests, so far, have given values the same as the workshop manual. Tests to ensure that the ignition high voltage isn't leaking to earth through the common ignition/6v lighting ignition switch prove negative. The plug insulator colour is white with a lovely tan coloured nose. The 'silencer' is the original Lafranconi, the exhaust pipe is the same and the spark plug is the correct type.

I thought that I might have some dirty fuel, the first time, but clean fuel in a cleaned system has made no difference. The magnetic trigger was also suspect at breaking down once hot, but the continuing to run and rev to 9,000rpm, once the "throat" has cleared, would tend to disprove that theory, I think. I have a Lambretta alternative available to fit.

The joys of Italian "craftsmanship"! :roll:

Good health, Bill

Scottish888
Posts: 266
Joined: Wed Feb 07, 2018 1:47 am
Location: Edinburgh, Scotland UK

Re: rich running

Postby Scottish888 » Fri Jun 18, 2021 7:02 pm

Bought a Hall effect 12 volt ignition system from the wonderfully helpful Nigel Lacey.
Converted the electrics to 12 volt with a chinese R/R following the info from this forum.Got all the wiring up finished today.
Set up the ign as per the manufacturers instructons, the stator is marked FA 28, 38 and 47, I set the motor to TDC and the stator at 38 deg.
The system generates a fat blue spark, I could hear it and see it by just turning the timing wheel around tdc.
Bike started second kick, after a warm up I revved it but it was still stuttering at higher rpm.
I then checked the ign with a strobe, it advanced fine to FA (full advance) but always settled at 28 deg when viewed with the strobe. It would stall if I advanced it too much at tickover.
I moved the stator around, the sweet spot seemed more advanced than I had set it, it certainly increased the tickover speed a lot but no matter where I moved the stator it always showed 28 deg, is that normal?
It did not rev out no matter where I set the stator so I put it in the middle of the slot until I can set up the wheel again.
I removed the rubber connector from the carb and the bike seemed to run much higher maybe even full but the rev counter cable snapped so dont know the number, it certainly seems to rev out to max.
I had tried that before with the ducati ignition systems and it made no effect.
So it looks like the new ignition system has sorted it along with removing the air filter tube.
Will need to get it on the road to see for sure but it seems much better.
Checked the voltage, it was going to 14,7 ish on revs, excellent
How about the ign always showing 28 deg on the strobe at lower revs?

Jordan
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Re: rich running

Postby Jordan » Sat Jun 19, 2021 3:25 am

What did you strobe against? The marks on the clutch cover?

LaceyDucati
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Location: Wales UK
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Re: rich running

Postby LaceyDucati » Sat Jun 19, 2021 7:43 am

Personally I wouldn't bother strobing the rotor as it is at half engine speed and too small a diameter to be accurate and parallax errors are also likely. The between full advance and the static strobe position will always be the same regardless what ignition timing you set it to as that relationship is the magnets to the trigger. What will be altering as you alter the timing, is the timing and the angular position of the rotor and backplate. As I explained to Colin on another thread, the easiest way to set this ignition is to mount a timing disc, position the engine to the maximum advance required (in your case 33-36 degrees for a W/C mark 3) and then simply move the pulse ring until the FA mark aligns with the mark on the rotor. If you require to check the ignition by strobe, the only accurate way to do this is to mount a suitably stiff and securely mounted timing disc and strobe it at the crankshaft. Strobing anything else is going to be fairly inaccurate. When setting a timing disc TDC is most accurately found with a positive stop, the use of pencils and clock gauges are all subject to dwell and the angular contact of a clock gauge subject to poor movement. The idea of using a clock gauge only really works on two strokes and engines with vertical mounted spark plugs but there is still an element of dwell.
The degree marks on the stator were added by Electrex in the belief that it would make it easier for people to set the ignition who do not have a degree disc. In reality without any TDC marks you have to mount a degree disc anyway and you may as well do the more accurate thing of setting it to a specific full advance figure then you know where you are. That said, the degree marks do offer the opportunity to find TDC with a pencil through the plug hole and just roughly line up the lines. The timing may not be within a couple of degrees but the bike will almost certainly run fine. I am not recommending this method but explaining Electrex's thought patterns when adding these marks.
As for why the static timing seems to be strobing at 28 degrees. I think its just a result of what you are trying to do and not the actual timing that is occurring. The position will always be the same away from the FA mark as it is the system advance. The addition of the specific timing marks is a classic example of trying to make something simple and actually making it more complicated and throwing up too many questions.
Regards Nigel
Last edited by LaceyDucati on Sat Jun 19, 2021 8:06 pm, edited 1 time in total.

Scottish888
Posts: 266
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Location: Edinburgh, Scotland UK

Re: rich running

Postby Scottish888 » Sat Jun 19, 2021 11:25 am

Thanks for explaining Nigel,
Very helpful.
I am very impressed with the spark from the new unit, good to see a healthy spark for a change.
The 12 volt conversion is also excellent and just a few pounds for a unit, what a difference in lighting.
Set up the timing as Nigel suggested, I use the oval case raised edge as a tdc point, the camera angle isnt perfect but once your eye is level it works fine. Set at 35.5, it wont be exact but as close as possible without a TDC stop.
Another pic you can see the timing was then set to FA with the timing at 35.5 btdc. the next pic is the position at TDC, showing 38 deg on the stator.
I then marked two points on the case with a staight edge accross the rotor marks, good enough to help me set up if I need later.
Bike started up first kick and easy, not run it to high revs yet, looking for a gear lever and still to make a new rear brake cable...and find a circlip that fits the brake pedal.
Before I set the timing up correctly today, I checked the static rotor position at tdc, it was about 45 deg btdc, this was set the day before by adjusting the stator until the engine run fastest and smoothest, why would it run "better" by being to advanced, is it ever good practice to rely on that?
Will update once I test it on the road.
Very happy with this new setup, hopefully it will prove to be the answer, I am glad I bought it.

Regards,
Alex
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LaceyDucati
Posts: 521
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Re: rich running

Postby LaceyDucati » Sun Jun 20, 2021 11:54 am

All sounds good and using the line on the inspection cover is fine, I've seen that done before. All I use for static timing discs is a bent piece of welding wire under a screw which can be bent for adjustment. I'm assuming you are just feeling for TDC via the plug hole, which will be somewhere close and almost certainly close enough if you aim for the mid timing spec. Proof of the pudding is of course always in the eating.

As to why the bike ticks over higher more advanced, maybe once running it doesn't really need as much retard especially with the improved spark. Certainly all my race bikes ran and started well on fixed full advance, however I didn't need to kickstart them!

Proof of the pudding is of course always in the eating.I await your testing once you've completed your "touring spec" conversion.

Regards Nigel

Scottish888
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Location: Edinburgh, Scotland UK

Re: rich running

Postby Scottish888 » Tue Jun 22, 2021 12:04 am

Rode the bike today, started first kick.
Bike seems to pull throught the rev band ok, both the speedo and rev counter cables broke on the last run out so I have no idea about revs.
The gearing feels incredibly long on country roads, it seemed to take ages to max out through the first 3 gears I would need to run it on the motorway if I even want to get into 4th gear.
Maybe a bit roughness at the very top of the range but that is likely to be carburation, I am still running the Dellorto at the moment but had to concentrate more on the narrow roads than listening to the motor so not an ideal test.
Going to say this issue has been solved with a combination of the new Hall effect ign system and disconnecting the air filter :D
Thanks to Nigel I bought a handlebar mount top yoke, forward foot rests and rear brake pedal. I have had the top yoke machined out to fit the spindle and it is on the bike but still using the clip ons for now as I need to source bars and levers that could take the Ducati adjusters.
More comfortable even with the forward foot rests, higher bars will make it better for me.
Thank you to everyone who contributed all the helpful advice, hopefully you can find a cure to any mechanical woes within this thread.
At least another Ducati single is on the road now. :D
plug after the high rev run.
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duc top.jpg

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themoudie
Posts: 649
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Location: Scotland

Re: rich running

Postby themoudie » Tue Jun 22, 2021 8:54 am

Good morning Alex, delighted to see you have the wee beastie out and about "Taking in the good air and making a good noise", OZLAVERDA! :D :D :D

Enjoy the Borders, rather than the M8 or M90. ;)

Good health, Bill

Scottish888
Posts: 266
Joined: Wed Feb 07, 2018 1:47 am
Location: Edinburgh, Scotland UK

Re: rich running

Postby Scottish888 » Tue Jun 22, 2021 6:01 pm

Well...
After a clear road test the bike still has problems, at full throttle it will gasp then backfire and repeat till the throttle is closed down more.
Plug looked the same as yesterday.
Put on the new Mikuni I bought from Allens and it is worse, stuttering and not reving cleanly. Not sure what jets are in it but it can't be that far off as I told them make and model.
The Mikuni could be miles out in jetting

Duccout
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Re: rich running

Postby Duccout » Tue Jun 22, 2021 7:46 pm

Alex, your bike seems like mine. Happy days!


Colin


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