Running an ignition winding only for racing?

[72degrees]

Anybody de-commissioned the lighting coils on a stator leaving just the ignition bobbin active for a racer with no lights?

Saves a tiny bit of weight and an even tinier bit of power absorbed generating volts surplus to requirements.

Seems a shame to experiment on a good stator but the lighting coils on the project engine aren't working anyway.

Can't see how to do it expect unwinding the lighting coils and leaving the cores in place. Is that likely to produce any weird flux effects that might cause issues? I don't expect it will produce a flux capacitor effect, though a few seconds of time travel might make up for lack of BHP

[penman]

I see you have no replies to your question, so I thought I'd throw in my tuppence worth! I don't think operating the unit with no windings will cause any ill-effects, you may have a little magnetic drag on the rotor, but you'll have that anyway. However, you say the alternator windings "don't work" - a very common cause of failure is short-circuit turns due to insulation failure, and shorted turns will be wasting energy and unnecessarily heating the stator. In which case, removing the windings would probably be a very good idea. Even if the windings are measuring open-circuit, there could also be shorted turns.

If you do achieve time travel, please come back and tell us all exactly what you did!

Regards,

Joe.

[72degrees]

I see you have no replies to your question, so I thought I'd throw in my tuppence worth! I don't think operating the unit with no windings will cause any ill-effects, you may have a little magnetic drag on the rotor, but you'll have that anyway. However, you say the alternator windings "don't work" - a very common cause of failure is short-circuit turns due to insulation failure, and shorted turns will be wasting energy and unnecessarily heating the stator. In which case, removing the windings would probably be a very good idea. Even if the windings are measuring open-circuit, there could also be shorted turns.

If you do achieve time travel, please come back and tell us all exactly what you did!

Regards,

Joe.

Good point. I really should confirm that there is no output from the lighting coils and then do a resistance test. It could be a regulator failure coincidental with the engine swap, or even a connection I didn't attach properly. I was much more interested to see if it ran OK so was concentrating on the ignition system.

The other approach would be a more conventional ignition system running from a 'total loss' battery. That would be perfectly adequate for speed hill climbs when you can charge the battery between runs. I know there are systems like the Sachs that use conventional coils and battery, but a bit pricey. I expect an electronic whizz could build a box that the OEM pickup could trigger to fire dyna-coils with a battery LT supply, but I'm not sure if the timing curve would be right without the effect of RPM on the stator ignition winding output? The NLM module I have on the test machine uses small coils as used on scooters. It works very well so may just get another for the hill climber once everything else is sorted.

The best way to achieve a second off all my times may be to fiddle with the timekeeping software that I help the NHCA with

If RiderNo = 314 then RunTime = RunTime - 1

[harrymuffin]

To run the bike with only the ignition coil working just leave the two yellow wire disconnected from anything. This was customary on the bikes used for racing in the seventies and was how the WeeVee racer I had was set up. If you have the stator with the white wire earth then you use just the ignition - green and the white up to the transducers.

[72degrees]

To run the bike with only the ignition coil working just leave the two yellow wire disconnected from anything. This was customary on the bikes used for racing in the seventies and was how the WeeVee racer I had was set up. If you have the stator with the white wire earth then you use just the ignition - green and the white up to the transducers.

That's what I've done since the original Morini hill climb bike in 1981. Just wondered if it was worth igetting rid of the redundant windings completely.

Another thing I must do is rig up a more efficient handlebar kill switch using an 'earth it out' rather than a 'switch off the juice' strategy.

[MickeyMoto]

Another thing I must do is rig up a more efficient handlebar kill switch using an 'earth it out' rather than a 'switch off the juice' strategy.

Isn't that how the standard kill switch works? Off shorts the magneto to earth, run is open circuit. The Kokusan needs 12 volts at the coils so is t'other way around. On feeds the coils and off is open circuit.

[72degrees]

Another thing I must do is rig up a more efficient handlebar kill switch using an 'earth it out' rather than a 'switch off the juice' strategy.

Isn't that how the standard kill switch works? Off shorts the magneto to earth, run is open circuit. The Kokusan needs 12 volts at the coils so is t'other way around. On feeds the coils and off is open circuit.

Indeed it does, but a 2C twist grip doesn't have a built in 'kill switch' and I have junked the rotary ignition switch with key on the 'racer' .The only thing I had in the scrap box was an 'open circuit' handlebar switch (with 'OFF' emblazoned upon it) rather than a push button to earth to the handlebar. This switch is in the green wire feed to the transducers. A push button on just one wire spliced to the transducer feed would do it OK so long as you keep it pressed long enough and it would save a metre or so of cable and extra connections that could give trouble. On a 4T twin (rather than a 2T MX single with no flywheel to speak of) comedy moments might result if released to soon but I'll probably invest in a cheap button off Ebay and convert to that.

[penman]

The other approach would be a more conventional ignition system running from a 'total loss' battery. That would be perfectly adequate for speed hill climbs when you can charge the battery between runs. I know there are systems like the Sachs that use conventional coils and battery, but a bit pricey. I expect an electronic whizz could build a box that the OEM pickup could trigger to fire dyna-coils with a battery LT supply, but I'm not sure if the timing curve would be right without the effect of RPM on the stator ignition winding output? The NLM module I have on the test machine uses small coils as used on scooters. It works very well so may just get another for the hill climber once everything else is sorted.

The best way to achieve a second off all my times may be to fiddle with the timekeeping software that I help the NHCA with

If RiderNo = 314 then RunTime = RunTime - 1

Sorry, took my eye off this thread! The stator output doesn't affect timing, though of course it needs to be correctly aligned with the rotor to ensure that there is output available when you need it. What you describe, using the OEM pickup to trigger a more conventional battery operated CDI unit is of course perfectly possible, though it would need a bit of development and I'm not sure it would achieve much. In particular, you would still have the original advance curve, controlled by the pickup. The Australian company Tri-spark have been making after-market ignition systems for British Twins and triples and some Japanese models for some years, with fancy features like idle stabilisation and anti kick-back and they have recently introduced a new unit which is programmable to work with 1,2,3 or 4 cylinders in all configurations including boxers and Vs. The advance curve is also programmable. At the moment they only make pick ups for a couple of models (not including Moto Morini!), but I'm told they are considering a "universal" pickup which would be interesting to anyone with the mechanical skills to adapt it to a particular bike. I think this unit also has a rev limiter. Not yet available, but it may be worth checking their website every now and again. Not likely to be cheap!

[MickeyMoto]

The only benefit of removing the coils would be the increase of power. Then again a 100 watt alternator with no load may get you 0 hp!

All you need the magneto for is to charge the capacitors. If you had a total loss system you could remove the stator and flywheel to save weight. What it would do to the engine, no idea. Stall? Spin up faster?

[72degrees]

An interesting thought about the rotor also providing flywheel mass.
In terms of ignition timing I was confusing the system with the more primitive type of CDI I had on the Rotax 2T.
I really must try the NLM pickup I still have in a box on a shelf again which at least allows fine tuning of the timing for each cylinder. I couldn't actually get the bike to start with it (even though they replaced the first one they sent). Must have been doing something wrong - or just not strong enough leg muscles.
It doesn't seem quite so crisp now it's back running with the OEM transducers from the 2C. I have a spare NLM CDI module (later type) so might just go with that.
A rev limiter (ideally adjustable) somehow hooked in to the existing system or shift light would be neat (saves the weight of the tacho drive, cable and instrument). I can probably risk a 'seat of the pants' limiter but the lad (who is much quicker than me and therefore likely to be getting it wide open where I won't) is used to 2Ts or modern 4Ts with rev limiters.

I've found DIY circuits on the internet and the feed for the electronic tacho (from OEM transducer 1 or the NLM module) could probably form the basis for it. but my soldering skills aren't up to it anyway. Plenty of cheap universal electronic tachos with shift lights on Ebay but not for a twin revving to 10000.

['It must be a .....']

Hi, you could run a coil ignition system from a battery and remove the stator, yet I would suggest you retain the flywheel.
I've run a Boyer based system for years; much better advance curve, smoother running, easy starting etc The only downside with the Boyer ignition is when the battery is nearly flat it won't retard the ignition and may kick back when starting (happened once).
See http://www.kirbyrowbotham.com/ignitions.php?page=7 my system was the prototype for a 500 motor and I've spoken to a 350 owner who said it was the best thing they ever did to their Morini.

Have fun, take care, Ian

PS Anticipate negative tales from Morini soothsayers.