At wits end with ignition - need help!

[DewCatTea-Bob]

[quote= STEVENM63 ...
" Here is some info
Alt wiring resistance measurements
White = 1.0 (currently connected to ignition) "

____ What you think is "White" wire-lead ought-to be the 'yellow-wire', as 1-ohm is about the correct resistance of the ign.power-coil.
__ You still haven't yet mentioned what ign.coil you're trying to use.
Your ign.coil with near 4-ohms is certainly not a 'match' for the 1-ohm ign.power-coil, and-so therefore cannot take full advantage of all the available-power (that could otherwise be provided, [with an ign.coil which has a matching 1-ohm primary-winding resistance-level]) !



" Red = 0.4 "

____ The red-wire (to the lighting power-coil) ought-to be .4 to .6 ohms, so that measurement you've got is as ought be.



" Green = 0.1-0.3 "

____ The stock alt.stator-cable doesn't contain any 'green' wire-lead !
However that color would be a more logical choice (than the stock white-wire of the '28-watt' stator), for use with the bat.charging-circuit, (which the 0.1 ~ .3 ohm-reading indicates is actually the intended power-winding for that circuit).
__ So it now seems that the original yellow; red; & white alt.stator wire-leads have already been replaced. - (Which ought-to solve Nick's concern about them.)



" It idles nicely, but unfortunately, once you bring it off idle it won't rev. It coughs and stalls with no power.
when I increase the throttle the engine won't rev up.
Any ideas "

____ Don't you have another carb you could try substituting, so as to learn if this issue remains or not ?
__ Otherwise,, I suppose that it could be that the mag.rotor-timing has been set off-time, after-all,
(likely back when the alt.stator wire-leads were replaced, by whoever).
Cuz in such case,, as the revs climb, the AAU will then advance the ign.timing possibly to a point when the mag.power-coil no-longer happens to be producing sufficient power to still adequately excite your non-matched ign.coil.


Hopeful-Cheers,
-Bob

[STEVENM63]

[quote= STEVENM63 ...

" It idles nicely, but unfortunately, once you bring it off idle it won't rev. It coughs and stalls with no power.
when I increase the throttle the engine won't rev up.
Any ideas "

____ Don't you have another carb you could try substituting, so as to learn if this issue remains or not ?
__ Otherwise,, I suppose that it could be that the mag.rotor-timing has been set off-time, after-all,
(likely back when the alt.stator wire-leads were replaced, by whoever).
Cuz in such case,, as the revs climb, the AAU will then advance the ign.timing possibly to a point when the mag.power-coil no-longer happens to be producing sufficient power to still adequately excite your non-matched ign.coil.


Hopeful-Cheers,
-Bob

Unfortunately, I don't have another carb. So do you think I have a carb/fueling issue? Is there another way to test this without needing a substitute carb?

[DewCatTea-Bob]

[quote= STEVENM63 ...
" Is there another way to test this without needing a substitute carb? "

____ Well if you have a suitable battery,, then the supposed-possibility of whether the mag-rotor-timing has not been properly set, could be tested (to help confirm the possibility that a dieing-off ign.spark is the cause of your eng.running-issue [as above idle eng.revs become effectively governed]). ...
To run the test (to see if your mag.powered ign.spark is the cause of the issue),, you'd need to disconnect all the currently-existing wiring (except the wire-lead to the points) away-from your (still unknown !) ign.coil. _ Then instead of connecting-up the battery to the ign.coil in the same mag.style-scheme, you must rather connect it to the opposite terminal (as the ign.points are left connected to) !
This alternate method for powering the ign.system, should reveal whether your running-issue is due-to maladjusted mag.rotor-timing (or something-else, such as fuel-mix).
__ While the points-ign.timing ought-to be retarded-back 3~6 degrees (from the '21'),, since this suggested ignition-setup ought be just temporary (for test-purposes only !), you could rather simply close the points-gap a bit -(like .002"), (so as to help avoid any kickback possibilities during your testing period).
And although the ign.spark should become much more healthy, (beings now that your 4-ohm ign.coil will be rather battery-powered),, that [likely battery-type] ign.coil could still possibly become overheated if ran too-long, since the points-cam of the '18-degree' AAU.model (which your eng.model ought employ) is-not intended for a battery-powered ign.scheme.
____ Since you don't seem to have any answer concerning what type of ign.coil you're using, then how about posting a picture of it !?


Hopeful-Cheers,
-Bob

[STEVENM63]

Great idea. I will have to pick up a 6 volt battery then.

[DewCatTea-Bob]

[quote= STEVENM63 ...
" I will have to pick up a 6 volt battery then. "

____ Don't you already have a car or truck battery that you could jump-connect from, just for the short test-trail ?
If your ign.coil is just 6v.rated,, it won't much matter, so long as you don't leave a 12v.battery connected-up to it very long. _ It should still work okay for the 1 to 3 minutes it'd take to test-out your engine's ability to rev beyond idle (with your present carb). _ (After running for up to 3-minutes,, the ign.coil-casing shouldn't yet feel heated-up, but yet may still become somewhat warm to the touch soon afterwards [after the inevitably warmed-up primary-coil finally transfers some heat to it's casing].)
However if you were to run it for over 10-minutes straight,, then you ought expect your ign.coil to become too-hot to hold-on to, and-then perhaps possibly incur some internal overheat-damage.


Duke-Cheers,
-Bob

[STEVENM63]

[quote= STEVENM63 ...
" I will have to pick up a 6 volt battery then. "

____ Don't you already have a car or truck battery that you could jump-connect from, just for the test-trail ?

Okay, excuse what is probably a dumb question, but won't a 12v car/motorcycle battery damage the 6v electrical components (condenser, HT coil)?

[DewCatTea-Bob]

[quote= STEVENM63 ...
" won't a 12v car/motorcycle battery damage the 6v electrical components (condenser, HT coil)? "

____ Once again, you've responded before I completed & signed-off my previous-post (with some related answering-info). _ (Of-course doing-so is actually nothing that really ought-to be avoided, as it's always certainly possible that such premature post-responding can possibly lead to the 'get-the-ball-rolling' process started sooner !)
____ Anyhow, no,, as the condenser can probably handle up to 30-volts, and the (6-volt RATED) ign.coil can still work just fine (so long as it doesn't become too overheated) !
Your 4-ohm ign.coil will draw 3-amps (from a 12v.battery) when the contact-points are left closed, and only about 2-amps while the engine is running. _ So when the engine is stopped, there's about a 2 out of 3 chance that the points will've ended-up closed,, so to assure keeping the ign.coil from getting too heated-up (about 50% faster), be sure to not leave the battery left connected whenever not running your test-trial.
__ So anyway, there's no real voltage-related worries to be concerned with, (at-least for the expected brief testing-period).


Enlightening-Cheers,
DCT-Bob

[STEVENM63]

After being out of town and handling some other obligations, I was finally able to get back into the garage. Here are some findings.

I did a brief test with a 12 volt battery from one of my other bikes, The bike was able to be started and seemed to rev okay while on the my work stand. I didn't do this very long because I noticed things were getting hot. I also retested the coil and got consistent readings of 3.9-4 ohms.

With that test out of the way, I retarded the timing a few degrees from where I had set it (originally 21* based on the table specs in the manual). I didn't put the degree wheel back on, I just retarded the points plate a few degrees based on feel (maybe, 8-10*). This was based on the position of the original points and condenser before I replaced and re-timed the motor to the specs recommended here and in the manual. The bike started and rev'd fine (although starting was a little harder, but still manageable). I took the bike for a quick spin and noticed that the bike ran fine until maybe mid-throttle and I would get what felt like a misfire. Okay, getting somewhere.

Did some more testing and investigation and experimentation with advancing and retarding the ignition timing and I was able to duplicate my previous tests. Next, I removed the left cover. While I currently don't have suitable tools to remove the clutch and flywheel, I did notice the position of the flywheel index mark was at 0* with the engine at TDC (see pic).

Ducati1.jpg

According to the manual, if I'm reading this correctly, a 0* rotor/flywheel position would indicate either a 350 motor, which I don't have, a 250 Mach 1 with no AAU (I have an AAU), or a 250 with a 28* AAU. The 28* AAU would require a 5-8* static setting instead of the 21* static setting that I set. So do I have the 18* or 28* AAU? Hmmmm. (see pic).

Ducati2.jpg

My timing settings were based on the 250 Scrambler, which I thought we established was what I had. If this is correct, then the flywheel/rotor position should be 32-36*, correct? I just wanted to confirm this before, I go taking the clutch and flywheel assemblies apart if I don't have to.

Thoughts?
Steve M

[Jordan]

If your engine uses a battery or capacitor for ignition (including CDI), then the alternator rotor position is not important.
If it's a magneto type ignition it will use a special, reduced range adv-ret unit, and rotor position is critical.

Jordan

[amartina75]

your AAU is the magneto type. notice the short cam lift duration compared to the longer lift of a battery ignition unit.

image.jpg