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AMC 20T genny spark

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AMC 20T genny spark

Post  rob spence on Tue Mar 27, 2018 6:27 pm

Hi, I've got to the point where I'm ready to test the spark from the generator. I presume the feed to the external coil is the maroon wire. And are they posi or neg earth?

rob spence

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Re: AMC 20T genny spark

Post  rob spence on Tue Mar 27, 2018 6:33 pm

Oops just looked at the wiring diagram on the internet, so that was wrong! Can anyone kindly tell me how to wire up just to get a spark from the sparkplug, not lighting as yet as I just need to test the condition of the coils etc.

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Getting a spark and running

Post  piston 197 on Tue Mar 27, 2018 7:03 pm

Hot wire it,
one wire from battery to coil SW side, preferably with a flick switch in line, other battery terminal to earth, other side of coil CB to points ( contact breaker)
you will now have an ignition circuit, but you will not have the generator connected so no charging circuit, your bike will run until the battery is flat and then it will stop,
You will need to wire up the charging circuit and a rectifier if you want your battery to be charged while running.
Not the final answer, but at least you can see if it goes or not ?
JH
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piston 197
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Re: AMC 20T genny spark

Post  rob spence on Tue Mar 27, 2018 7:12 pm

Thanks JH, but the object of this excercise is to test the generator. With my pals Montesa the stator has 4 wires, 3 work different lights (brake light, headlight, horn) the 4th black wire provides the power via the points to the external coil. Is there a similar way the FB can can do this? ie use the genny to power the spark plug with no battery, or is it a totally different set up on the FB? By the way there is no wiring on the bike yet apart from the 4 wires coming from the genny.

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i was trying to make it easy

Post  piston 197 on Tue Mar 27, 2018 7:21 pm

I was trying to make it easy for you,
Firstly your engine does not have a "Generator", i has an ALTERNATOR !, this does not have wires which provide spark and lights , this generates AC Voltage which provides an AC voltage, this has to be fed through a rectifier and be converted to DC voltage to run lights and ignition from a battery, the alternator only provides power to the battery via a rectifier to charge said battery.

The Trials models 83 and 85 used a different unit which was designed to run without a battery, so unless you have fitted one of these you will not have self generating ignition and lights, if you have fitted one of these you need to look for a wiring diagram for these models and then you will not need a battery at all ?

Perhaps you are a little out of your depth wih the electrics and may require some help from a competent electrician, if i am wrong then i apologise
JH
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Re: AMC 20T genny spark

Post  rob spence on Tue Mar 27, 2018 7:30 pm

You are correct bike electrics are not my forte, hence my questions. A trials unit is obviously what I need... just like the Montesa.

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Re: AMC 20T genny spark

Post  rob spence on Tue Mar 27, 2018 8:21 pm

JH, just as a matter of interest... with the standard alternator and rectifier setup can a really small battery be used, or would it suffer from overcharging?

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small battry ???

Post  piston 197 on Wed Mar 28, 2018 6:21 am

It is not the physical size of the battery, it is the capacity ot the battery that is in question, i suggest you go for a Burlen type solid state battery with no liquid acid, then it can be mounted uposide down sideways or whatever your preference and the amp hour rating will more than cater for the charging system, their 6 volt battery is 5 amp hour @ 21 and is more than adequate, these batteries will also keep their charge for up to a year if not used
JH
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Re: AMC 20T genny spark

Post  rob spence on Wed Mar 28, 2018 10:00 am

Thats great info JH, in that case there seems little point in me going down the competitin coils route. As its almost as light. Many thanks.

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AMC 20T alternator

Post  FB vincent on Thu Mar 29, 2018 3:53 pm

This is the test routine published by FB and James for the Wipac alternator as fitted to the 20T and 25T engine. You need a copy of the FB User manual to fully understand how the system works.


WICO PACEY ALTERNATOR ELECTRICAL EQUIPMENT


FALCON 87


We have compiled a simple test procedure using improvised test gear to assist in locating faults to avoid the unnecessary replacement of components.

TEST APPARATUS.
1. A 6v 36w bulb, with holder, and two test wires about 24" long.
2. A 6v 04 amp bulb with holder and two test wires about 24" long.
3. A well charged 6v battery.
Note. 6v 04 amp bulbs are sold by all cycle shops for bicycle dynamo rear lamps.

TO CHECK ALTERNATOR OUTPUT.

Start by disconnecting cables from alternator at the connector. Join the two test leads with the 36w bulb in the holder to the white and green cables, run the engine at a fast tickover speed.
Transfer the test leads to white and orange cables; If the alternator is normal the bulb will light fairly brightly on both tests.
Should the bulb light differ much on one of these tests the-alternator is at fault. If the bulb fails to light the alternator is defective.
Note. A dull light on both tests can be caused by a sub-normal rotor, particularly if the battery connections have been reversed.

CHECKING ALTERNATOR COILS FOR EARTH.

The six coils are wired in two banks of three coils, the white cable is common to both banks. Connect one of the test leads using a 6 volt battery and 6v 04 bulb to a good earth point, the second test lead in turn to the white, green and orange cables. If the bulb lights, one or more of the coils are shorted to earth. Having verified alternator is in order, turn to the rectifier.


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Re: AMC 20T genny spark

Post  rob spence on Sun Apr 08, 2018 8:31 pm

Thanks FB vincent.

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Re: AMC 20T genny spark

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