Well you asked for another Ducati build

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buzzer
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Re: Well you asked for another Ducati build

Post by buzzer »

tony.mon wrote: Thu Sep 03, 2020 7:25 am Nice work!
Does the original sensor also have two sensors?
I thought it was only one, sending the point of field collapse to trigger an ignition- on the Firestorm engine, anyway.

Does your setup still run wasted spark?

the original on the Ducati is a single induction sensor, which gives a sinusoida wave form. thats OK for most instances but it does have disadvantages... firstly you need a fairly large diameter wheel (like a flywheel) to sense off. then you need to calculate at what point on the slope on the wave form the sensor picks up the signal... again that's OK as you can enter a compensation factor in the ignition software, however the point on the curve that it triggers is not linear in that it moves along the curve as revs increase.

the hall effect sensors have some distinct advantages. firstly they work off a square wave form, so it's essentially on or off with a precise cut off point that does not change with RPM. they can also be used on small diameter wheels, Like a cam wheel in this instance as they are not reliant on a chunk of steel passing in close proximity like the induction ones. They are also physically small. Most cars and bikes use Hall sensors these days for things like crankshaft and camshaft position sensors. they are also cheap... these we £1 each!

using the hall sensor also allowed me to get rid of the wasted spark as I can configure the software to spark every second revolution :D
MK_WF
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Re: Well you asked for another Ducati build

Post by MK_WF »

buzzer wrote: Wed Sep 02, 2020 4:13 pm I have used an Ignitech ignition unit that utilised the original induction sensor. While the bikes ran OK, I had to make adjustments in the software to compensate for the fact that the values in the software differed from what was actually happening on the bike, plus the tick over was not as steady as I would have liked…
Next time give this a try :
The Ignitech calculates the actual rpm and also a delta rpm per time directly from input signal.
Unfortunately the rpm vs time is not constant. On a V twin you overlay a pretty high irregularity.
If you use a standard VR sensor you actually measure one point of that curve and use the "previous" point in history to calculate the "next" one.
To be able to spark before the pick-up position, the Ignitech sparks "at the next rotation". Therefore the mentioned prediction is used to determine when this will occur.
The more irregularities you have, the more the prediction will deviate and make the ignition advance jerk around at idle.

But there is a trick.
If you set the first rpm value in the ignition curve bigger than idle rpm, it will not calculate anything but "directly" use the base advance (i. E. fire at pick up position). That angle will be constant vs time, i.e. no jerking around.

I agree that the support from Ignitech could be better as I had to find out the above by own testing.

BTW: Theoretically the trigger system, be it VR or Hall, should have no influence.
But I suspect that using 2 magnets to switch on/off that are some 10 crank deg apart will kind of smoothen out the irregularities during that time period because you "measured" two points and use the medium value. (Electrically I'd call that a filter.)
So if the measured input points are more consistent, the extrapolated predictions will be, too, and as a result you'll get a more stable idle.
Bye
Martin
buzzer
Posts: 111
Joined: Tue Feb 19, 2019 10:41 am

Re: Well you asked for another Ducati build

Post by buzzer »

MK_WF wrote: Thu Sep 03, 2020 10:52 am
buzzer wrote: Wed Sep 02, 2020 4:13 pm I have used an Ignitech ignition unit that utilised the original induction sensor. While the bikes ran OK, I had to make adjustments in the software to compensate for the fact that the values in the software differed from what was actually happening on the bike, plus the tick over was not as steady as I would have liked…
Next time give this a try :
The Ignitech calculates the actual rpm and also a delta rpm per time directly from input signal.
Unfortunately the rpm vs time is not constant. On a V twin you overlay a pretty high irregularity.
If you use a standard VR sensor you actually measure one point of that curve and use the "previous" point in history to calculate the "next" one.
To be able to spark before the pick-up position, the Ignitech sparks "at the next rotation". Therefore the mentioned prediction is used to determine when this will occur.
The more irregularities you have, the more the prediction will deviate and make the ignition advance jerk around at idle.

But there is a trick.
If you set the first rpm value in the ignition curve bigger than idle rpm, it will not calculate anything but "directly" use the base advance (i. E. fire at pick up position). That angle will be constant vs time, i.e. no jerking around.

I agree that the support from Ignitech could be better as I had to find out the above by own testing.

BTW: Theoretically the trigger system, be it VR or Hall, should have no influence.
But I suspect that using 2 magnets to switch on/off that are some 10 crank deg apart will kind of smoothen out the irregularities during that time period because you "measured" two points and use the medium value. (Electrically I'd call that a filter.)
So if the measured input points are more consistent, the extrapolated predictions will be, too, and as a result you'll get a more stable idle.
that's really interesting Martin! What I am struggling with is that the Ducati uses a single induction sensor on a 48 tooth gear wheel that has 2 teeth missing, so its counting 46 teeth and triggering off the gap. I cant see how the gap gives any base advance, as the gap corresponds to TDC on the horizontal cylinder? If you want to take this discussion off line, feel free to drop me an email to jtcccjunk@gmail.co I would love to hear more on what you think!
MK_WF
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Re: Well you asked for another Ducati build

Post by MK_WF »

On any toothed wheel theres a gap that is used as a reference position.
The software recognizes that gap and sets its "zero point" internally to that position.
The software internally counts the first tooth after that gap as tooth 1.
In the bike tab you specify at which tooth the individual cylinders should spark.

What you program with the base angle is what crank angle this trigger tooth is sensed. If it's TDC, then it's 0 deg.

All map values refer to this base angle.
If you entered 30 deg BTDC it means "spark 330 deg after the gap was sensed"

On the VTR that base angle is 15 deg, so the same 30 deg entry would mean "spark 345 deg after the gap was sensed"

This is the "secret" how you can use one toothed wheel with just one pickup for multiple cylinders.
Check your original .ign-file what was entered for your 48-2 wheel.
I guess "special setting", "missing lobe", number of lobes =46 and then the according tooth numbers for the trigger position.
Bye
Martin
buzzer
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Re: Well you asked for another Ducati build

Post by buzzer »

you have a FAR better understanding than me Martin! Thanks! :thumbup:

here are a couple of screenshots... i never understood the tooth count thing. the Ducati fires at 270 degrees, and I guess each tooth is 7.5 degrees... given that, do you think the tooth setting is correct?

Image

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MK_WF
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Re: Well you asked for another Ducati build

Post by MK_WF »

Yeah, I once dived deep into that when I set up my VTR, but already forgot most of it.
Basically you got the idea: missing tooth is giving the counter the start command, then it's counting until the specified number and saves "this position is the base angle". Then it extrapolates the time when the crank will be at the desired angle from the ignition curve/map and fires at that point.

Your ign-file pretty much looks like I'd expect. Give it a try and change the first rpm value to something higher than idle. Maybe like 1700. (also slightly shift the second one).
That should calm the idle advance to a constant 7 deg BTDC.


The good news : There's an easy way to find out if everything was setup the right way.
I always strobe the whole thing.
If the bike has a mark on the flywheel, then set an ignition curve to be constantly that value vs rpm.
The VTR has one at 15 deg BTDC, so I used 15 deg.
If there's no mark, measure piston position and do your own at a reasonable value (like 10-30 deg BTDC).

Then strobe the running engine. If the mark aligns, the base angle and tooth number was ok.
If not, I usually tweak the base angle until the marks align.
Here you could "test" what a changed tooth number would do. Theoretically changing from 19 to 20 should give you an offset of the calculated 7.5 deg between the marks. A correction from 7 to 14.5 deg for the base angle would then re-align the marks.
Note that in this case your idle advance will also go up to 14.5 deg and you'd need to check if the engine likes that better. On my IMR Pitbike I tried lower and higher values and it needed about 10-15 to feel good.

Don't forget to repeat that for cylinder #2.
If marks don't align here, do not touch base angle (otherwise you'd change cyl 1, too). Use the correction values under the ignition curve.

If marks don't perfectly align, never mind. You can only set full degrees, so the deviation will always be under 1 deg.

Now as you have the bike running anyway, increase revs up to max and check if the mark wanders.
If yes, change the value for compensation.
(It always takes the same very short time to create a spark, but as the engine revs up, the crank angle within that time is different. That's what the compensation is correcting)

After testing, don't forget to change to the "right" advance curve!
(don't ask why I pointed that out)

BTW: You need to repeat this every time you had the flywheel/trigger wheel off.
Bye
Martin
buzzer
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Re: Well you asked for another Ducati build

Post by buzzer »

Thanks for your help Martin! I may re try the setting in the future, but for now I have the hall sensors working well



well its running really well now, and it's got a very stable tickover... dry clutch always sounds like a bag of spanners through!

here is a short video...

https://youtu.be/M_b45UEcvsA
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nigelrb
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Re: Well you asked for another Ducati build

Post by nigelrb »

Looks really impressive!!
Dickiebig
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Re: Well you asked for another Ducati build

Post by Dickiebig »

Have to agree looks and sounds great!!
buzzer
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Re: Well you asked for another Ducati build

Post by buzzer »

Now for the part I actually enjoy doing… the wiring! I am building this loom completely from scratch, save for things like the handlebar switches, although I am replacing the outer sheathing as it was tatty. I know this is something a lot of people struggle with but over the years I have developed a system… I start with a design in my head and I put it down in rough on my Ipad, using an Ipencil which I find brilliant. then I transfer it to visio, which I print out and add the colour of wires on as I go along. I don’t try to it all on one diagram like in workshop manuals, but keep separate pages for different circuits like lights, indicators, ignition… I also create tables of key components where they have pin outs.

All this is put into the build folder which I always pass on when I sell the bikes.

I have a nice crimp tool which is normally sufficient, but if I am in any doubt I put a dab of solder on the joint. I also don’t use pre insulate connectors, instead I put 20mm of heat shrink on which makes a nice joint, and the heat shrink also supports the joint. If you use the glue lined heat shrink, it also makes the joint waterproof. this is of course if I am not using super seal connectors which are not only excellent, but also cheap! and finally, I use the most useful little kit, which has tools for removing all types of pins from connectors!


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nigelrb
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Re: Well you asked for another Ducati build

Post by nigelrb »

^^^
Above and beyond. Way above most DIY skills I am sure. :thumbup:
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alanfjones1411
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Re: Well you asked for another Ducati build

Post by alanfjones1411 »

I wouldn't even know where to start :confused
SO WHEN DOES THIS OLD ENOUGH TO KNOW BETTER KICK IN
Dickiebig
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Re: Well you asked for another Ducati build

Post by Dickiebig »

Well done that man !
All good stuff
Once again I admire and envy your skills
MK_WF
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Re: Well you asked for another Ducati build

Post by MK_WF »

Funny coincidence: When bench testing my Ignitech units, I always fake a VR signal by using a Megasquirt Stim Board (= a function generator for 12/5 V rectangular signals) and put a capacitor in series.
The Ignitech input circuit seems to cope fine with the voltage after the cap.

And for curiosity: The Ducati has no additional ignition box meaning the Ignitech TCI outputs go directly to the HT coils?
I'm asking because the VTR can be run either with a TCI P4 or a CDI P2.
The TCI is used solely as a timing unit, the spark is then created by the VTR's stock ignition converter.
When using the CDI, you could skip both stock boxes (the ICU and the converter).
Bye
Martin
buzzer
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Re: Well you asked for another Ducati build

Post by buzzer »

hi Martin, yes, the output from the ignitech unit goes straight to the original coils. if you go to this site and buy an ignitech manual there is some really good technical information on ignitech and ignitions in general. the guy is called Liam Venter, and he is a mine of information! as its so cheap he asks that people buy the manual rather than share, so I respect this...

http://www.fastbikegear.co.nz/index.php ... ts_id=6233
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