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Misc: Ignition Lucas Rita



coldrider

Website User
VOC Member
#1
Hi - my Lucas Rita AB11 amplifier (system supplied by Mistral Engineering years ago) has gone belly up. The AB15 externally looks identical. I haven't got a clue what the difference between the AB11 and the AB15 is. Does anyone know what the differences are and if it would be interchangeable with the AB11? Any help/advice most welcome. Until then I remain spark-less!!!!!
 

Bill Thomas

Well Known and Active Website User
VOC Member
#3
Hello, Just a thought, I had trouble with mine from almost new, The switch side of the front coil was faulty, I have had trouble with those mini coils befor !!, But with that setup, If the front coil goes, the way it links with the second coil, You have nothing, I was lucky, I was at the side of the road pulling at the wires, Not knowing what I was doing and it went Bang !, Lucky I had left the ign' On !!, So now I knew where the fault was, I remembered I had a 12v mini coil in my tank bag, I know they should be 6v, But I put it on anyway, And it worked !, Good Luck, Bill.
 

b'knighted

Well Known and Active Website User
VOC Member
#4
I put a used Rita on a Comet running a single 12v coil instead of two 6v in series. I used to set it up then show off by starting it with my hand.
 

coldrider

Website User
VOC Member
#6
Hi - my Lucas Rita AB11 amplifier (system supplied by Mistral Engineering years ago) has gone belly up. The AB15 externally looks identical. I haven't got a clue what the difference between the AB11 and the AB15 is. Does anyone know what the differences are and if it would be interchangeable with the AB11? Any help/advice most welcome. Until then I remain spark-less!!!!!
Thank you for info. I tried contacting Mistral but they were unobtainable. The whole Moira project has also stopped. So no luck there! However I'd still be interested to know the difference between an AB 11 and AB 15!
 

b'knighted

Well Known and Active Website User
VOC Member
#7
So how does that work Ian, Is there a lost ! spark, How did you wire it ?, Cheers Bill.
I found a single cylinder wiring diagram at http://www.britcycle.com/Manuals/333135RitaInst.pdf

Looking at it again, I don't remember earthing the white/yellow coil wire, but I must have done as worked. Mine was a Vincent twin set-up with the asymetric cam so there is a wasted spark. I decided that as it should occur on the exhaust stroke it wouldn't be detrimental. I believe that Mistral were at the time offering amplifiers with their advance curve optimised for Comets but I used what I'd got and was very pleased with it.

If the Series D coil set-up I'm using on my 636 Comet fails I'll happily fit the Rita. I'm sorry to hear that the Moira isn't available as it sounded even better.
 

Robert Watson

Well Known and Active Website User
VOC Member
#8
I ran Lucas Rita on my twin for a few years and tried to run it on small coils that did not have a full 3 ohm resistance. They would go about 2500 miles and then fail. I also found that the setup used a great deal of power about a constant 3 1/2 amps, even with big 6v 3 ohm coils. I used AB11 amplifiers and still have 2 or 3 of them kicking around. I have no idea the difference between them and an AB15 but I seem to remember that these ones only gave 24 degrees of advance at the crank, and it was a delicate thing to get it retarded enough to not kill you when starting and enough to get it to run nicely. After a few years I took it all out, converted the Mistral unit to accept the Harley D two stage electronic stuff, and have never touched it in about 70,000 miles. If I think of it I put new plugs in, maybe twice in the past dozen or more years........
 

davidd

Well Known and Active Website User
VOC Member
#9
Carleton and I ran the Rita on the racers. Two problems: the Rita consumed huge amounts of power, which was difficult for total loss systems and second, if you left it on by mistake it would burn out the power transistor on the circuit board. Fortunately, Alan Johncock helped Carleton by ordering some power transistors and he soldered them in when necessary. They were good as new. We assumed when they were dead it was a power transistor problem and it always was. We started with rollers so there were no advance issues.

I have not tried the HD units, but those who have seem to like them very much. I think Bob Lamour sells them.

David
 

BigEd

Well Known and Active Website User
VOC Member
VOC Forum Moderator
#11
Also if you leave the plug lead off and kick over with Ign' on it would blow the amplifier, Cheers Bill.
I think this is possibly true for several electronic ignition devices. The original magnetos had a safety gap screw that gave a path for the spark to jump harmlessly to earth if the plugs weren't earthed.
People may have discovered this screw when they have dismantled a magneto without removing it snd then found that the protuding screw has damaged the plastic flange on the slip ring.:eek:
It is a good idea to earth the plugs if you are turning the engine over with the plugs out.
 

Normski

Well Known and Active Website User
VOC Member
#12
I have a spare AB11 amplifier which you can buy or borrow-I'm away from tomorrow ( Monday)midday but if you send me an address by first thing I'll try to get it in the post before I go.
 

geoff b

New Website User
VOC Member
#17
mine was the first vin to have lucas rita ,as mistral gave me the unit to try on my motor it has been there ever since! not changed a think ,just use the two 6 volt coils mistral gave me . I use the machine regularily through most of the year and done the odd track days for years . there is a company advertises in old bike mart , who now do a replacement electronic board that's takes place of the original board and claim it is far more reliable than the lucas one . I believe the cost for the board is £75 and its a do it yourself repair just found edvert ,its rex,s speedshop tel 01580880768 it is £75
 


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