250 Monza: vicious kickback

[cooperplace]

The bikes starts and runs well, but most times I try to start it, it gives a vicious kickback, the sort that makes you wonder if all the ankle bones are intact. I will retard the timing a bit, because other posts here suggest that could be issue. If anyone has any advice, I'd be grateful for it.

[Jordan]

A possible cause of good running but severe kickback is an advance/retard unit that is seized.

[Bevel bob]

Could be fitted with the wrong advance unit,the timing only needs about 5 degrees advance when static set,also the springs could be bust or the unit seized.

[cooperplace]

I've now adjusted the ignition timing through almost the full range, not quite to full retard. Still vicious kickbacks. I had the advance unit out while I was reassembling and the springs looked fine, it wasn't seized.
I will remove the CD ignition unit.
It also has an odd habit of backfiring when I turn off the ignition key. This is with the engine NOT running!

I've got to fix this problem: my ankles aren't as young as they used to be, and I don't to break one.

[cooperplace]

after removing the CD ignition, the problem is gone. It's now easy to start, no or minimal kickbacks. My ankle still hurts.

You live and learn. I've had great results with these units with other old points ignition engines.

[Bevel bob]

I fitted a cheap Pazon points assist unit ,The spark has always been reliable and the points dont burn, the condenser is not needed . I dont need to use a strobe ,the unit has a built in timing light which just peeks out from under the front of the tank on the drive side (where i fit a timing disc) .I can retard or advance the ignition for tuning on the roadside by just openning or closing the points gap by a thou or two. What could be easier?.The advance and retard unit can be worked on to increase the range which allows you to set the base static timing back a few more degrees to eliminate any tendancy to kick back.I have the battery /coil system .

[DewCatTea-Bob]

[quote= cooperplace ...
" most times I try to start it, it gives a vicious kickback,
If anyone has any advice, I'd be grateful for it. "

____ Your ankle will be grateful for the chance to rest & heal, as soon as you begin practicing the staring-procedure of turning-on the ign.switch after you've levered the piston just-past the compression-stroke and then turn-on the ignition and kick from TDC (each attempt) !




" I will remove the CD ignition unit. "

____ What "CD unit" ? _ You haven't told us anything of that !



" It also has an odd habit of backfiring when I turn off the ignition key. This is with the engine NOT running! "

____ Turning-off the power to the ignition-system has the same effect on a saturated ign.coil as when the ign.points open, except that the resulted spark is rather fired at a random-time !



" after removing the CD ignition, the problem is gone.
I've had great results with these units with other old points ignition engines. "

____ CD.type ign.systems rather SHOCK the ign.coil with a jolt of pumped-up voltage (and results with a much shorter spark-duration), so your CD.unit must also dump it's cap even when just the battery-power is interrupted, (instead of waiting for only the points to do it).
__ How-about telling us something about your particular 'CD-unit' and exactly how you had it wired-up & connected into your points-type ign.system ?


Dukaddy-DUKEs,
-Bob

[Jordan]

This is puzzling. Even with electronic assistance for the points, surely a functioning advance/retard unit would provide the needed retarding at start up?

I don't know if this helps, but I have a BSA, originally made with points ignition, onto which I installed a Boyer-Bransden pointless electronic ignition system.
It does not use an adv/ret unit. Rather it relies on the waveform from the trigger coil (which changes shape with revs) to provide the function.
Interestingly, with a well-charged battery, it works well. But, with a weak battery, or in my case a battery eliminator, there is no retard action. It'll run OK once started, but kicks back. A charged battery installed, and it goes well again.

[cooperplace]

V interesting. My unit is a dynatek:

http://www.dynaonline.com/skins/product ... _Boosters/

I always use the techniques described by Bob: only turn on the key after the lever is at TDC. The unit was installed acc. to the makers instructions: there's nothing to it.

I don't know why the unit turned my 250 into The Kickback Monster From Hell, but it sure did, and my ankle still hurts. The CDI will stay off the bike.

[DewCatTea-Bob]

[quote= cooperplace ...
" I always use the techniques described by Bob: only turn on the key after the lever is at TDC. "

____ If you had actually meant 'piston' rather than "lever", then you shouldn't have gotten any kick-backs !
____ If a spark is always created by shutting-off the ignition-switch, then it may be possible to rather start the engine by turning it off & on quickly, after priming the fuel-charge just-past comp.TDC.
Too-bad you've already removed the suspect device,, as since your experienced kick-back was strong enough to kick your foot so very hard, then it also may've just as well been possibly strong enough to start-up the engine (without having to kick-lever it).


Hopeful-Cheers,
-Bob