Results from timing check.. to be interpreted - Ducati.ms - The Ultimate Ducati Forum
 
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Old Apr 13th, 2018, 1:00 am Thread Starter
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Results from timing check.. to be interpreted

Hi all

Following on from my thread about kicking and ignition issues I've managed to get hold of a timing disk and a strobe. So this afternoon I packed a bag with tools and a rag and rode up the hill behind the house - I try not to sit around revving my bike out my front door for my neighbours' sake.

I had my Gopro on my jacket and used that to capture some clips of the results. I trimmed the video down to two clips of the top cylinder and one of the bottom. That video is here https://youtu.be/pGAgC1za6cM

The attached images below are the top twice and the bottom twice, plus a snap f the disk so one can see the marks.

This is what I saw:

With the cable attached to the upper spark lead, the strobe would show the upper case mark to be a degree or more to the left of the line marked V-AA on the disk.

With the cable on the lower lead, it showed the other/lower/left case mark to be close to the line marked V-AA on the disk (not the one marked O-AA)

In both cases, there was no change at all when increasing RPM.

In addition, the lower header had become very blue, whilst the upper had no bluing at all.

So, can anyone here interpret this? I've read that incorrect/reversed wiring (of what exactly?) can cause there to be no advance and that a blue header also indicates this.
  • I'm unsure whether the AA mark is the initial or the advanced mark.
  • I'm also unsure why the test on the lower lead pointed to V-AA and not O-AA.
  • What I am sure about is that the wiring is wrong.

I get the impression that I probably don't need to adjust the pickups and that this will largely resolve with wiring fixes.

Any comments on how to proceed are appreciated.
Regards
Rob
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Last edited by robax; Apr 13th, 2018 at 1:03 am. Reason: Replace YouTube embed with link as it is low-res.
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Old Apr 13th, 2018, 6:35 am
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you reverse the wiring for each cylinder at the connector from the pickups. don't mix up o and v though.

as for the marks, i'd pull the plugs and find tdc. that'll give you the best indication.

Brad The Bike Boy
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Old Apr 13th, 2018, 10:49 am
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Hi Rob,

I hate these ignition systems! The front cylinder should show O-AA when full advanced and the rear V-AA, plus when opening the throttle from idle the spark should clearly advance - 6 degrees at 900 RPM, advancing to 16-18 degrees at 1800 RPM, then 28 degrees at 2800, until full advance is reached at 4000 RPM.

I'm surprised that the bike will run at all if the wiring is incorrect, although a previous poster said the reversing the wiring to the pick-ups will stop the advance, so that looks to be your first port of call.

Keep us informed.

Colin

Ducati GT1000, Ducati 900S2 Bevel
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Old Apr 14th, 2018, 12:35 am Thread Starter
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Thanks for the comments Colin and Brad

So today I was going to simply swap the wires for each pickup and go off to check it all again. However once I had everything apart, I decided to recheck everything I had done when I wired this up a couple of years ago. At the time I posted a thread here where I was very confused about the official circuit diagrams versus what I knew myself and what the pickup maker was telling me.

I've posted a 17 minute video showing what I'm seeing in the manuals and what I eventually did on the bike. It all appears to be correct and the only grey area is the assumption that striped leads on the pickup should go to to striped leads on the bike. I would be reversing that assumption if I go ahead.

https://www.youtube.com/watch?v=1u8kYdJvRQI

The question at the end is simply - Is it really likely that the polarity of the two pickup coils is the problem here? If it is, then I'll change it and put it all together tomorrow and check it. I assumed that the electronics simply detect a change in impedance on the coil and do nothing with any polarity it might have.

As for the confusion about the manuals, I may be completely stupid in my interpretation of the diagrams, but they really don't make sense.
Regards
Rob

Last edited by robax; Apr 14th, 2018 at 12:36 am. Reason: Stupid forum keeps embedding the video even when I say not to
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Old Apr 14th, 2018, 12:41 am Thread Starter
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p.s. When I talk about the horizontal cylinder 'firing first' I simply mean the first one after the longer gap. Obviously none actually fires first.
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Old Apr 14th, 2018, 12:55 am Thread Starter
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p.s. again as it seems to confirm the polarity question:

This specific post by mad max in this thread over at Bevel Heaven talks about the polarity mattering:
Darmah Ignition Repair Adventure - -=- Club Bevel Heaven -=-

And then he answers himself two posts further down:
Darmah Ignition Repair Adventure - -=- Club Bevel Heaven -=-

Seems to be telling me I need to wire stripe to non-stripe and test it.
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Old Apr 14th, 2018, 2:07 am Thread Starter
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And one more p.s.

This is the post I referred to where Steve said crossing the wires would make it run full advance:
Ignition pickup polarity, how do I check? - -=- Club Bevel Heaven -=-

Everything certainly points to this being the problem.
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Old Apr 14th, 2018, 3:09 am
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Hi Rob,

I've watched the video (very good!) and looked at the links. The workshop manual explains that the view of the pick-ups and the rotor is from the engine side cover, so is inverted, but that does not explain why the horizontal pick-up wiring goes to the vertical cylinder; it could just be a typo, for vertical cylinder read horizontal cylinder.....

It does appear that crossing the pick-up wiring will stop the engine advancing, which would explain the kick-back and rough running and hopefully, the pick-ups are in the correct position for timing. I do know that if the pick-ups are not set with the correct air gap to the rotor then the ignition will not advance properly too, as I've experienced this. The full-advanced setting is not so critical - a very clever guy who used to make high tech ignition systems for racing engines told me once that old four strokes don't mind if the timing is one or two degrees out.

You must be very fed-up by now, but at least you are technically minded, just imagine the problems if you had no knowledge of electrics!

Colin

Ducati GT1000, Ducati 900S2 Bevel
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Old Apr 14th, 2018, 4:02 am
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from memory reversed wires will have it at full advance all the time, not at idle advance. but, regardless, if it's not advancing, swap the wires.

if the pick up gap is too small they will generally idle on the first step, which means as you lower the carb slide stops to lower the idle speed it will lose the first step of advance and then idle very low. but that's about the only issue i've seen with pick up placement.

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Old Apr 15th, 2018, 7:03 am Thread Starter
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Alrighty... results from today.

I pulled the pins from one side of the pickup plug and simply swapped them so that the striped leads would now go to the plain leads. Then I went for a ride and set it up to check the timing again.

Note that the previous test resulted in very strong blueing on the lower pipe, but no blueing at all on the upper. The bike ran but only badly and there was no advance, or it was permanently at full advance, detected on the timing disk.

Here's a video made up of seven or eight clips.
https://www.youtube.com/watch?v=js1WJXlwahw

  • The start and six and a half minutes riding up the hill. It really ran just as badly as it did before. Had to keep the choke on to keep it going.
  • I rode it several minutes longer than shown here.
  • Then I found a spot and set it up for the strobe. I got it on the stand and tweaked the stops to try and get it to idle without having to hang onto the throttle.
  • At 10:36 one can see the timing and then just a quick rev where I checked for any movement. The result was basically identical to the previous test. Same position on the timing disk, and no change on throttle.
  • At this point, the GoPro app had the clips in the wrong order and one can see the bike stalling in my driveway at home.
  • Then I packed up and was unable to start it. I pulled the plugs and then swapped them. Still no kick start but I got it started on the slope leading back down.

The bike ran very badly and it really only ran at all with the choke on. It vibrates a fair bit as mentioned previously. There is a lot more video of it banging and popping. I checked plugs earlier on. The lower one was black and wet around the edge, but dry and lean looking in the middle. The other was very sooty, sticky and also a little wet.

The only thing I noticed was that the upper pipe had now also become very blue, same as the bottom one previously. I then actually tried switching the polarity of just that pickup just in case it made a difference. It didn't

At this point I'm resigned to swapping my old original pickups into the new cover. I know of a guy up North who has the factory calibration tool and so I could at least get things back to how they were. The new pickups are the only thing that is actually new in this equation and so I really need to take them out of it. It's just weird how they work, but they don't.

I'm interested in knowing if there is anything mechanical that might cause this sort of problem. I can't see how, but I'd like to be able to exclude any other possible causes. Even with these issues, the engine felt very strong when I briefly opened it up, so I can't imagine it having any such issues.

Thanks again for any comments.
Rob

Last edited by robax; Apr 15th, 2018 at 7:04 am. Reason: argh hate this stupid embedding feature, keep having to turn it off.
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