Motoscrubs.com

How do I set up the static ignition timing on my 1974.
It is fitted with the original Ducati system, I have a strobe but would like to know how to set it up for the first attempted start.
Not sure on the ignition rotor and stator where any alignment marks are.
Pic is pre rebuild

Kind regards

The procedure is described in the user manual. Unfortunately, I have an italian version only

The Haynes manual https://haynes.com/en-gb/ducati/desmo-singles/1969-1976 has the english translation.

cheers

Aye Alex,

You need a strobe timing light (xenon type is preferable), a timing pointer and preferably the Haynes workshop manual! Once statically timed, this can then be adjusted dynamically.

Personally, having thrown the electronic ignition (EI) away in 1976 after it went phut, I never timed EI on a Duke single as the contact breaker points were fitted. I have now fitted an after market (EI) and have yet to run the motor to complete the dynamic timing. Mine being a 450, it has a very different static and advance timing from your 250.

Mike has the necessary pointer that is unobtainium and that you will need to make up for yourself. A graduated plate to attach to the outer clutch case is also a desirable accessory as this enables you to set the timing to the unmarked degrees recommended in the Haynes manual.

I will send the relevant pages from the Haynes manual (p78-80), plus the scale, as a PM due to file size.

Building a seat at present!

Regards, Bill

Thanks all,
Ducwiz, those diagrams are very helpful, hopefully I can get it set up in reasonable starting mode with that
Bill, I have got a haynes manual so will consult that more closely but I don't think there was much in it about the initial static setup.
How many mm before tdc should it fire? I can measure that at the plug.

Regards

Aye Alex,

Whilst I can measure the number of mm BTDC that the piston crown is when my 450 is 36-38 degrees BTDC. But, the 450 has a different stroke and the plug is at an acute angle to the crown of the piston that on the 450 is flat crowned unlike your domed crown piston. Therefore, making the likelihood of us obtaining the same measurement in mm for the crankshaft position being at 36-38 degrees BTDC, unlikely.

Others may care to opine about this, as my maths is not good!

From your image, it appears that you have the 'Ducati' pickup in the 250, so you are looking to align the two dots on the right side of the unit at 36-38 degrees BTDC.

Hope this helps, Bill

Hi,

my Italian is not the best, but I am basically able to translate from the manual, p. 28 and 29:

- find compression TDC
- turn the crankshaft clockwise until the following angles are indicated
- 54° for 250
- 42° for 350
- 36° for 450
In this position, respectively, the marks /dots on pickup rotor and stator must align precisely

The procedure is an initial setup only, to make the engine startable. A fine adjustment is necessary using a strobe light and the indicator tool.

My comments:
Until today I use the Ducati CDI, without problems. The Motoplat stuff is crap, got rid of it.
The markings on the primary cover are not very precise, check them against your TDC identification.

cheers Hans

Aye Hans,

Agreed, those are the degrees BTDC given in your Italian handbook.

In the Haynes manual, with reference to the 250, 350 and 450 singles it says and I quote " 4. Turn the engine backwards by about 50 degrees, then gradually turn it forwards to 36degrees - 38 degrees BTDC. In this position, the index marks on the pickup rotor and stator should align. If necessary, move the stator until this setting is obtained, then tighten the securing screws."

In paragraph "5. It should be noted that it is possible to 'cheat' slightly at this stage, in that it is normally feasable to guess the setting with sufficient accuracy to enable the engine to be started. On no account should the engine be used, however, if the timing is approximated in this way, even though it is quite in order to use such a rough setting as a basis for stroboscopic timing".

I believe that Nigel Lacey has seen and then rectified more than one example of enthusiasts purchasing electronic ignition systems that enable different advance curves to be used/programmed and for the engines then fail spectacularly due to radical, for the engine, full advance positions BTDC being used, in the false belief that this would result in an improvement in engine performance!

I did on one occasion achieve an orange/red glowing exhaust pipe on the 450 in under a minute, when initially setting up the points and getting myself in a muddle between the directions to advance and retard! Hence, I have a slight paranoia about ignition timing now.

Good health, Bill

Bill,

I agree as well with your statements. From my point of view, the values in the Ducati manual are not the precise ignition timing angles, but mechanical references, which roughly let us achieve the correct timing. Therefore, they appear to have a too high advance angle. If a strobe is used after the preadjustment, this will be evident.
For refence, I add here 3 pages from the Clymer manual, which describe the adjustment of the point ignition. An (unfortunately incomplete) table of the actually needed advance angles is given there.


Finally, I added a link pointing on a very elaborate instruction: "Setting the Ignition Timing (advance) on a Ducati Single" https://www.vintageveloce.com/p/setting-ignition-timing-advance-on_7.html. It covers the points igition exclusively.

cheers Hans

Thanks for the info,

My original Ducati ign does not have any basic setup dots to align.
You can see in the pic I put a blue dot on the indent in the rotor and made another on the stator but there is no original dot/mark on the stator.
Pic is taken at TDC, I set the white mark on the stator to line up with the top left tip of the rotor, then marked a couple of blue dots. The bike was set up like that before I stripped it but no idea if it was correct or is a factory alignment position.
You can notice another casting mark on the top side of the rotor that could be a BTDC mark? If so, I guess I just need to line up the TDC mark for initial starting then use those two points with a strobe later.

Does anyone have this standard system fitted? Any photos of the TDC or BTDC setup position would be appreciated