Wiring stock 160 ignition?

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Classictrial
Posts: 17
Joined: Wed Nov 29, 2017 12:46 am

Wiring stock 160 ignition?

Postby Classictrial » Thu Dec 21, 2017 8:16 pm

Have been having problems with CDI ignition system on this 160 trials bike and have decided to revert to stock points and see how they work. I read somewhere that the brake light is powered from the source coil and this can cause problems. Wonder is anyone can clarify this at all and also outline where the flywheel needs to be in relationship to the source coil and what position the motor needs to be in when fitting the flywheel?
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Eldert
Posts: 771
Joined: Sun Nov 01, 2009 3:23 pm
Location: Hazerswoude Rijndijk Netherlands

Re: Wiring stock 160 ignition?

Postby Eldert » Thu Dec 21, 2017 8:53 pm

looks like you have a Lucas Rita system fitted . those kits where made and sold by Mistral engineering in Chigwell Essex

the only problem i ever had with those were a misfire do to lose rivets on the pick up . replaces witn stainless steel screws and problem solved

Eldert

Jordan
Posts: 1380
Joined: Fri Dec 24, 2010 11:29 am

Re: Wiring stock 160 ignition?

Postby Jordan » Thu Dec 21, 2017 9:40 pm

Are you asking for information on how to provide for a stop light with points ignition and no battery?

JimF
Site Admin
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Re: Wiring stock 160 ignition?

Postby JimF » Fri Dec 22, 2017 12:26 am

On some Ducati singles that have lower-powered alternators, the brake light was wired "in series" with the ignition coil.

The only thing that is problematic about this arrangement is that if and when the brake light bulb burns out or vibration breaks the brake light filament, the engine will die when the rider steps on the rear brake pedal.

Typical on the narrow-case Mark 3 models is an "emergency" toggle switch built into the taillight bracket that was implemented as a way to 'nurse' the bike home or to a hardware store when the bulb failed. The switch would bypass the bulb, allowing the motorcycle engine to stay running when the brake was depressed at the expense of having no functioning brake light whatsoever while you continued to ride in traffic. Once you put a new bulb in you had to remember to flip the switch back to the non-emergency position to get the brake light to work again.

Other models that used this arrangement didn't usually have the "emergency" switch.

Why was it like this? Since the headlights were 25-watt units, there was only enough power left to run the ignition system. A brake light is usually about a 15-watt bulb. In an arguably clever move, Ducati was able to use a lower-cost low-power alternator and solved the problem of how to implement a brake light like this: The ignition coil needs to be grounded for the ignition to work and the bike to run. Rather than just run the ground wire to the frame, Ducati ran the ground wire to a normally closed single-pole single-throw (SPST) brake light switch. The other terminal of the switch was grounded and since the switch was normally closed the ignition coil was grounded and the engine ran.

The brake light bulb, or to be very clear the high brightness brake light filament of the dual filament bulb was wired to the same side of the switch as the ignition coil. The other side of the light bulb was grounded. Since the brake light switch is normally closed and the other side of the switch is connected to ground, both sides of the switch are grounded when the switch is closed. The brake light too then is grounded on both sides of the filament so the brake light does not light.

When the brake is depressed the switch goes from closed to open. The ignition coil needs to be grounded to run but the switch connection to ground just went away. What happens then is that the ignition still sees a connection to ground; it is through the wire that goes to the brake light filament, through the filament itself which is nothing more than a nichrome wire in a vacuum and onward to ground on the opposite end of the filament where the bulb is grounded.

The engine continues to run, and now the same ignition current (amps) passing through the ignition coil also passes through the brake lamp filament and the brake light bulb lights up.

Release the brake switch and the engine continues to run as the ignition current goes back through the closed switch. The brake light shuts off as both filament connections have gone back to being grounded.

It's a clever system until the brake light filament fails. Then when you step on the brake the ignition coil is no longer grounded and the engine dies.

I think this low-power alternator arrangement with the brake light wired in series to the ignition coil was only ever implemented on motorcycles that had AC (alternating current) electrical systems, but I am not 100% certain of that.

I suggest you post your flywheel question under it's own topic to get it more attention.

Jim

ducwiz
Posts: 604
Joined: Tue May 22, 2012 12:52 pm
Location: near Frankfurt, Germany

Re: Wiring stock 160 ignition?

Postby ducwiz » Fri Dec 22, 2017 4:31 pm

Hi,

A.O. Services in the UK sold RITA/Mistral Ignitions http://www.hoppybikes.co.uk/moira.htm at last, but unfortunately stopped this service in 2016. On their website you can download some hints http://www.aoservices.co.uk/info/RITA.pdf.
These electronic igitions are battery powered (afaik), so the stock wiring schematics are useless for you. I suppose there is a R-R device on your bike, and a small battery as well, if indeed a RITA/Mistral was installed.

cheers Hans

Classictrial
Posts: 17
Joined: Wed Nov 29, 2017 12:46 am

Re: Wiring stock 160 ignition?

Postby Classictrial » Sat Dec 23, 2017 10:55 am

Bike currently has an Electrex CDI system fitted (which is faulty) and I am trying to refit the stock ignition system which works from a source coil within the flywheel magneto and has points/condenser with an HT coil under the tank.

There is an OHC manual in the tech section of the site but cant seem to open or access it now unfortunately as it had a diagram of where the magneto flywheel needs to be fitted in relation to poles of the stator coils.

From JimF's very helpful reply though it seems as though without rewinding the source coil, the stock system is not going to be reliable anyway so seems as though testing the bike at an event on the 27th December is out of the question anyway.

Lucas Rita is not a CDI system but is TCI which replaces the points and advance retard unit. Its a good system for road machines fitted with a battery but not that great for off roader without battery.

Many thanks for all the replies and hope everyone has a good Christmas and prosperous new year.


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