Bogging down/ rough running problem

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mbmm350s
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Location: Berkshire UK

Re: Bogging down/ rough running problem

Post by mbmm350s »

Hi Matt,
Its hard to know what you mean by 'wobble' - could you put a video on line someplace?

For me its usually blurry like its not totally precise some jitter maybe, but jumps in timing aren't good.
How many degrees do you think?
There shouldn't be any misfiring, and any loss of spark will of course appear to retard and then recover.

It is certainly worth making the appropriate mark on the flywheel for ANT2 and comparing for the rear cylinder.

It could be plugs, leads, pickup, transducers, generator, earths or wiring, we don't know yet.
Mark
Matt Hale
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Re: Bogging down/ rough running problem

Post by Matt Hale »

Hi Mark
Thanks for getting back so quick.
I'd say it moves 3 degrees either side of vertical maybe. Good to hear that you don't get perfectly still mark and jitter is a good word for what I see. The misfire might be carburettor...or pickup...
I will try checking rear plug..but not sure how to make ANT 2 mark - TDC on rear cylinder and tappets loose?
I've got new spark plugs, new transducers, generator coil has been re-wound proffessionally, I have re-done earths on frame, HT leads have new rubber caps checked but not replaced but I think they OK- I will buy new wire/leads
That leaves the pickup on your list...

To ride -the bike starts easily but deteriorates when hotter- after about a mile or two of riding...
I'll try doing a video...
Last edited by Matt Hale on 13 Oct 2022 08:25, edited 1 time in total.
350 Sport 1979 electric start model (missing)
Curry yellow tank etc paint work, navy blue frame, silver wheels.
BumbleBee
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Re: Bogging down/ rough running problem

Post by BumbleBee »

You can often remove excessive "wobble" by fitting a new cam belt. If the belt is too slack it creates wobble at the pickups.
Sometimes the rotor of the pickup unit is to blame, it's only pressed together and bits of it can get wobbly.
Also the top pulley can sometimes be the source of wobble at the pickup unit if it has any play on it's shaft or the key that is supposed to hold it still has worn.

G&A
mbmm350s
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Re: Bogging down/ rough running problem

Post by mbmm350s »

I will try checking rear plug..but not sure how to make ANT 2 mark
On the rotor PMS2 is marked, so simply measure back using a tape the same distance that ANT1 is from PMS1. Scribe the line for ANT2.
I've got new spark plugs, new transducers, generator coil has been re-wound proffessionally, I have re-done earths on frame, HT leads have new rubber caps checked but not replaced but I think they OK- I will buy new wire/leads
That's excellent.
So it does look like the pickup could be the problem.
Dont worry about damaging the pickup electrically that's hard to do, however don't drop it!

I think Norbert already mentioned the fault of the pickup that the timing appears to go backwards after a certain time, but it can occur on the rear cylinder or front or both(rarely) . If we can see it then we know that the fix will be good.
I wouldnt worry about the wobble at this time, first is to cure the misfire, the misfire is surely lowering rpm and then its recovering and hence appearing as jitter

There are suggestions from bumblebee as to what to check mechanically as to jitter cause.

Mark
Matt Hale
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Re: Bogging down/ rough running problem

Post by Matt Hale »

Hi All- I have made a short vid with sound to show what my ANT1 mark does at 6,000rpm (jitters a bit?) and to show the sound of the engine- slight popping/misfire? at constant 6,000rpm (second half of video). The idea of showing this is that you all laugh and tell me I obviously need a new pickup and rotor...The pickup is set with the arrow on the mark as usual and that seems to put the ANT1 mark as near to vertical as possible...

VIDEO OF ANT 1 @ 6,000 <https://www.youtube.com/watch?v=KqLP20qDcaI>

To G&A-Many thanks- I have checked and I don't think my cambelt has more than 6mm when pushed inwards as shown in the manual. I also don't think any play on top pulley or magneto flywheel.

Many thanks AGAIN !


Matt
350 Sport 1979 electric start model (missing)
Curry yellow tank etc paint work, navy blue frame, silver wheels.
MickeyMoto
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Re: Bogging down/ rough running problem

Post by MickeyMoto »

Have I seen this correctly? There appears to be no advance. The transition from tickover to 6,000 rpm appears to have little movement. It could be my eyes. How far around is the pickup? Does the arrow on the pickup point approximately to the timing line on the engine?
BumbleBee
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Re: Bogging down/ rough running problem

Post by BumbleBee »

Matt Hale wrote: 13 Oct 2022 11:18
To G&A-Many thanks- I have checked and I don't think my cambelt has more than 6mm when pushed inwards as shown in the manual. I also don't think any play on top pulley or magneto flywheel.

Many thanks AGAIN !


Matt
No worries. Assume you meant pickup rotor not flywheel?

As Mark said, the jitter isn't the immediate problem, but no harm done if you find the cause along the way.
mbmm350s
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Re: Bogging down/ rough running problem

Post by mbmm350s »

Matt,
Agree with Mike the advance is all wrong, non existent.

The engine runs clockwise when viewed from the Right hand side.
So when turning the flywheel clockwise ANT1 precedes PMS1 past the reference point , so as you rev the bike the strobe position of ANT1 should move to the left How about this for an understanding, if you had zero advance then the gun would show PMS1 as vertical wouldn't it.
As you rev it the timing advances and hence PMS will appear to move to the left, until eventually ANT1 comes into alignment
It looks like you are on full advance and revving doesnt do much except over advance it and cause misfire.
Timing should be at something like 22-27 degrees at fast tickover of advance. (27 is more likely with scooter transducers)

If you have the blue transducers you must rotate the pickup to retard by around 7-8 degrees of cam (14-16 degrees of crank) before attempting to strobe time. I think i already mentioned this. This is because the advance of the scooter transducer is designed for 18-23 degrees and not 34 degrees.
Hopefully below you can see the adjustment - this is a 250 which has same timing the upper mark is for standard transducers and the lower mark is for scooter style transducers. Your original reference point could be in a difference place, hopefully it was marked!

Image
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Matt Hale
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Re: Bogging down/ rough running problem

Post by Matt Hale »

Thank you very much Mark, Mike + everyone else! Back now and reading very carefully. I’ll try not to ask anymore for a bit!! Thanks again! :)
PS addition: I retarded pickup as suggested and ANT1 starts to right of verticle/ clockwise and moves anti clockwise towards as I increase revs. …but it can’t get to vertical. Starts popping as when pickup set on original mark. If I retard more I can’t start it but will keep trying.
350 Sport 1979 electric start model (missing)
Curry yellow tank etc paint work, navy blue frame, silver wheels.
Matt Hale
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Joined: 08 Oct 2020 10:00
Location: London

Re: Bogging down/ rough running problem

Post by Matt Hale »

I have set the pickup as your 250 photo Mark and can get bike to start and it ticks over fine. On both cylinders ( I made an ANT 2 mark as advised) when I rev up to 6,000 rpm both ANT marks don’t move anti clockwise to vertical (advanced) position. The marks pretty much stay still and popping misfire occurs as in original position.
350 Sport 1979 electric start model (missing)
Curry yellow tank etc paint work, navy blue frame, silver wheels.
mbmm350s
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Location: Berkshire UK

Re: Bogging down/ rough running problem

Post by mbmm350s »

Hi Matt,
So it seems like you have limited change in advance on both cylinders.And importantly that the system can't sustain full advance
I am a bit confused as first you said there was advance and then you said there wasn't. The advance is pretty small from fast tickover to 6000 rpm it's only going to be 7 degrees or so or about 1/6 of the distance from PMS to ANT. Retarding an ignition won't make an engine harder to start.

I think you should try the spare pickup, set to the position I suggested for scooter transducers.

It's rare to have a pickup fault on both cylinders.
The too advanced and then timing goes backwards symptom is like what you see when a black pickup is used with early transducers. They don't have the diodes in the pickup. So is it possible that both diodes in the pickup have gone short circuit? There is of course a common earth inside the pickup.

Don't worry about asking questions
Mark
Mark
Matt Hale
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Re: Bogging down/ rough running problem

Post by Matt Hale »

Hi Mark
Thanks again- I am away from my till 25th Oct so can't check things till then. I may try putting old transducers back on. I removed as thought causing problem but maybe not...
Speak again next week!
Matt
350 Sport 1979 electric start model (missing)
Curry yellow tank etc paint work, navy blue frame, silver wheels.
Matt Hale
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Location: London

Re: Bogging down/ rough running problem

Post by Matt Hale »

Hi All
I am hoping/ need to use blue ignition boxes-Ducati - (32398112) I am trying to order a replacement red pick up from Markus Heilig. <mheilig@freenet.de>
Does anyone know another option/place to get one?

I currently have a red pick up...so I am wondering if I can switch to use this black one at Modina? <https://www.mdinaitalia.co.uk/M460565.html>

Thanks - Matt
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350 Sport 1979 electric start model (missing)
Curry yellow tank etc paint work, navy blue frame, silver wheels.
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themoudie
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Re: Bogging down/ rough running problem

Post by themoudie »

This all reeks as being very similar to the problems that Leonard and I are having with our 125H singles. See the 'Singles' threads on the forum.

I know that the 125's are running a different ignition triggering system, based on a Vespa scooter flywheel timed system and the 350V uses trigger coils on the end of the camshaft.

But, the fact that the ignition is not advancing at 6,000rpm and the engine splutters and stutters when approaching these revs, whilst using blue transducers/HT units makes me wonder if there is a similar problem to that which we are having with our 125H engines.

It would appear that many 40 - 50 year old Ducati ignition systems are failing! :evil: And so far the reasons do not appear consistent, or easily diagnosed, even by people who are knowledgeable about "Electrickery"!

I shall keep an eye on this thread, just in case a "Ureaka!" moment happens.

Best of luck, Bill
mbmm350s
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Re: Bogging down/ rough running problem

Post by mbmm350s »

Hi Matt,

Yes you can use the third series pickup (from the Kanguro/K2/Camel ) it is known as the black pickup the rotor of the second series as you have is compatible.
In order to use it with original black transducer or the scooter transducer you must put a diode in each red lead to the transducer. The cathode of the diode is connected to the transducer. The diode type is not so important a normal diode is good. 1N4007 or similar

You cannot use it without the diode modification and please don't try it, the ignition will appear ok for a while then retard.

You can also get a pickup from Mr Alex Luzzi of Siena (alex.luzzi@gmail.com in English its ok) it is also like the black but he will supply the diodes, but he can also supply transducers with exact compatibility with the black pickup, no need for diodes AND it has the tacho output.

I am running the pickup from Luzzi, 1000 miles no problems on a 350 its lovely.

To allay any confusion about the blue transducers on the twins these work perfectly, and are sold by the German suppliers.
but the tacho drive is lost.

I still think there is insufficient ability to compensate the system for the blue transducer on the 125H.
Alex Luzzi can supply replacement exact replica for the 125H transducer (black green spot) .

Cheers
Mark
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