250 Monza: vicious kickback

[cooperplace]

Hi Bob,
sorry, I meant "piston": I always get it to TDC before kicking. And I only turn on the ignition key when doing that kick. I'm not in a hurry to re-connect the device: my ankle still hurts!

[Jordan]

A timing strobe light can confirm you are getting some adv/ret action.

[machten]

I would think you have to have timed it wrongly. All the Dyna is doing is replacing the points. No more than that. I've used the Dyna S on twins many times and on both my own round case twins.. It's a set and forget system. The Dyna does need a strong battery, I've used an Electrex system for one of my singles to replace a Ducati Electonica CDI system. It's been brilliant and like the DE CDI, doesn't require a functioning battery to run.

Kev

[cooperplace]

I tried it all full advance, in the middle of the adjustment, and almost full retard, and the kickbacks were the same every time. There's not that much adjustment. I don't understand it either, but my ankle still hurts. It sure gave a vicious kickback, seemingly no matter how the timing was set. I'm going to leave it alone for a few more days. And I'll wear boots, not running shoes, in future when I kick start it.

Meantime my 900S2, which only has electric start, has shagged the sprag clutch and the starter gear. It makes me nostalgic for jap bikes.

[Jordan]

Still guessing - is there a chance the gears that drive the ignition shaft are incorrectly meshed?
Can you fit a timing disc, to find out when the timing point actually happens?

[cooperplace]

I don't think those gears are wrongly meshed. And the advance unit worked nicely in my hand. The bike starts and runs nicely with the CDI off, and the symptom has gone. I'm thinking that the CDI might have been faulty.

I understand how they work, so I can't see how I could get a kickback when it was definitely at TDC, and I kicked, and it viciously kicked back. Unless the unit had some weird fault. On the odd occasion that it started, it ran v well with the CDI, but it was a nightmare to start.
My ankle still hurts, and I'm in no hurry to put the CDI back on.

[DewCatTea-Bob]

My unit is a dynatek:
http://www.dynaonline.com/skins/product ... _Boosters/

By: cooperplace ...
" The bike starts and runs nicely with the CDI off, "

____ The link you provided seems to rather lead to a Dyna-unit that's not a "CDI" device but rather a circuit-device which is meant to spare the ign.points from having-to conduct the full current that the ign.coil consumes.
__ "CDI" usually stands for 'Capacitive Discharge Ignition', which is a completely different circuit-operation than that which the Dyna-unit's circuit provides ! _ So it seems that you should stop referring to your "CDI" ign.unit (or whatever it actually is) as such, and rather refer to it as whatever it actually is that you had meant your posted link to address.



" the symptom has gone. I'm thinking that the CDI might have been faulty. "

____ If the only change you made concerning anything to do with your ignitionsystem, was the removal of the suspect ign.unit,, then your thinking is certainly a logical-deduction !

I always get it to TDC before kicking. And I only turn on the ignition key when doing that kick.

" I can't see how I could get a kickback when it was definitely at TDC, and I kicked, and it viciously kicked back. "

____ If you correctly prepped the engine to just-past COMPRESSION-TDC and-then powered-up the ign.system and gave a mighty -(whole-hearted) kick-through of the foot-lever, and yet then still ran-into any kickback,, then either the ign.advance is set way too far advanced, or something rather spooky is going-on.



" Unless the unit had some weird fault. "

____ It could be that the "unit" is prematurely firing-off somehow without waiting to-be triggered by the ign.points. _ Perhaps the unit-casing depends on being well grounded and your ground connection is able to become disturbed (while kicking the bike), thus causing the unit to be triggered unexpectedly and rather fire-off somewhat randomly. _ Otherwise, I can't imagine how-else it could happen to be (apparently regularly) triggered just before the ign.points open (and [purposely] re-trigger it).



" On the odd occasion that it started, it ran v well with the CDI, "

____ In which case, that'd tend to confirm that the premature (& seemingly spontaneous) ignition is somehow rather randomly triggered (as like by a loose-connection).


Hopeful-Cheers,
-Bob

[cooperplace]

apologies if I've misled by incorrectly referring to the dyna unit as a CDI; my understanding is that these units work by discharging a capacitor, and I would be grateful for further advice on this.

[DewCatTea-Bob]

[quote= cooperplace ...
" my understanding is that these units work by discharging a capacitor, "

____ Well most-all electronic-gadgets contain capacitors which charge-up & discharge, but that unit doesn't include one which shocks the ign.coil (as in 'CDI').



" I would be grateful for further advice on this. "

____ I suggest you try & see if you can contact the maker's tech.department for answers concerning it's particular operation.


Hopeful-Cheers,
-Bob

[cooperplace]

It's still giving occasional kickbacks, but I'm not so worried because I now wear heavy boots which seem to absorb it better. The Dynatek points booster unit is disconnected.

Once the bike starts it runs very well.

The interesting thing is, if I take the plug out and turn on the ignition, I only see a spark at the points as they open, so they seem to be behaving OK. But if I leave that removed spark plug connected to the HT lead, and hang the plug so it's contacting the head, then it gives a single fat blue-white spark just when expected. BUT it also occasionally gives random much weaker yellow sparks at other parts of the engine cycle. I think this is the cause of the problem. Has anyone ever seen this? Could an internal coil fault cause this perhaps?

I would like to try it with another coil. The coil on it is completely anonymous, 12v, 4 ohm, has a + and - on it, no other markings.