Postby DewCatTea-Bob » Mon Sep 20, 2010 6:49 am
By: Nigel...
" I saw this thread and thought I might add a bit of info. "
____ And very good info at that !
It's always quite nice when someone offers such useful straight-forward knowledge ! _ And I didn't see a single point that was questionable, either.
Thanks for all of that !
" the system is designed to be set at 38 degrees BTDC at full advance with a starting (static) timing of 9 degrees BTDC. "
____ So then the answer to the info I stated would be helpful to know, is that the system offers 29-degrees (instead of 28) of auto-advance span, and has been meant to be pre-set with a 9-degrees BTDC static-setting. _ That's indeed good to know ! _ And that seems well suited for covering both the 250 & 350 engines !
" The system is set up at TDC to a mark which will give you 38 degrees BTDC. However, if you align the marks with the engine at 9 degrees ATDC this would give you a maximum advance of 29 degrees BTDC and a start advance position of zero degrees. "
____ If I understand that correctly, then it seems that the system's makers expect for their system to be installed/set-up while the crankshaft is kept a TDC, and the makers have pre-placed a "mark" (on their rotor) to be aligned with TDC, so that the installed system will then be expected to produce a max-advance of 38-degrees (total), with the static-advance intended to be (pre-set)at 9-degrees BTDC.
And so therefore, if the installer were to choose to rotate the crankshaft 9-degrees past TDC, (instead of keeping it at TDC as expected by the makers), while then fastening the supplied rotor-mark to the crankshaft, (the same 9-degrees, retarded),, then the resulting static-timing would be at the (possibly desired) stock 0-degree/TDC-point, with the max-advance point then being at only 29-degrees BTDC (instead of the intended 38-degrees).
__ If I had had anything to do with their choice of ign.timing for their system (to cover all three motor-sizes), I would've suggested they try increasing the auto-advance span (from their current 29-degrees), out to 33-degrees wide, and just pre-place three separate marks on their supplied rotor, (providing static-timings of [+/-1]; 6-degrees & 2-degrees BeforeTDC for the 250 & 350, and 2-degrees AfterTDC for the 450).
__ (I don't know why Ducati didn't produce 33-degree AAUs for their battery-powered ignition-system equipped models, in the first place.)
" As to whether this start point of the advance in this position of zero degrees can be compared to the static timing of a 450 at zero degrees, I don't know. "
____ If this means to state what I think it does, then I would think it quite reasonable that indeed they do directly compare. _ Cuz otherwise, their max-advance also wouldn't directly compare to the stock max-advance timing either, (as it actually does seem to). And I doubt that they were daring to second-guess Ducati's min & max settings (by more than 2-degrees), without extensive dyno.time.
However, the advance-curve's timing-plot is still in question, but as you've pointed-out, it's pretty-much insignificant.
" As you already have the ignition and I presume it's fitted, I would try setting the ignition as above and just see if it works. This is of course all at your own risk, not that I think it will hurt the engine..... "
____ Here I'm sure that Nigel is actually confident (as I am that he's right) on what he has meant to suggest, but just feels a (slight) need to allow it to be known that it's of course YOUR-baby.
We know that if the ign.timing is indeed set at the intended figures given within this post, that there can be no resulting damage caused !
Just check with the maker that the figures given here are not off (by too much).
" My only other reservation about this ignition and other crank triggered ignitions available,
If your flywheel moves or even creeps, with these ignitions, your timing is gone. "
____ This is a good point...
Flywheel-rotors with this added responsibility need to be keyed-in, and most are ! _ So for these non-keyed/stock DUKE-crankshafts, ya better make sure everything is torqued-down good-n-tight ! _ And if there's any added method to fixing the rotor to it's placement on the shaft-taper, then it should be considered.
There's another thread somewhere here that discussed ways to 'key' the rotor to the drive/pinion-gear... I'd look into that.
" A lot of the ignitions available for Ducati Singles reach their full advance by 3000 revs so for most sporting singles and race bikes once you are started, the advance curve is pretty irrelevant. "
____ I do agree and if it weren't for the need of kick-starting, any advance-curve would be next to useless, since it really doesn't have much effect on power even within it's limited low-RPM operating-range.
DUKE-Cheers,
-Bob
PLEASE NOTE... If this-post is not-yet signed-off with '-Bob', then I'm still in the process of completing it,, and if not also included with 'DCT' near bottom as well, then I may edit this post's wording at a later time. - Dct.Bob
Although I have a Rita system fitted to my own road single I have only got the standard alternator using a Honda regulator/rectifier which works fine for me. Finally.... as most of us never go out at night it's debatable whether you need a 120W alternator (unless the original ones down on power or been mullered by a previous enthusiast 