Lucas Rita ignition

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hayabusaman0

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Hi, on my 850 I have 2v only to r/h coil & 9v to l/h coil, same readings at the multiplug, on the side of ign unit is a resistor with 9v one side and 2v the other, with resistance reading of 9.2 ohms. Can anybody tell me if there is a fault with the black box or anything else I can check?

Cheers Paul.
 
Welcome hayabusaman0,

Firstly, do you have some kind of ignition problem?

Or are you just concerned about the readings you have measured?

From your description, I think you have the old Lucas Rita AB5 unit with the external ballast resistor?
 
Hi,yes I do have an ign prob, it will only run on l/h cyl, when switching ign on & off i have a spark from the l/h plug and no spark from r/h
 
OK,

There ware various coil configuration options for the Rita AB5/AB11 systems, but if you have a problem on only one side, then that problem is likely to be either the coil, spark wire (HT lead), plug cap or plug (AB11)?

But I don't quite remember how the AB5 differs from the AB11, so could you say which type and voltage the coils are, and could you also give a brief description of the amplifier/coil wiring layout please?
 
Thanks for the reply,the unit is the AB5 with ext resistor,6v coils, wiring is as follows, white/black wire from black box to - on l/h coil, red/black to r/h coil, red(earth) to + on coils,12v supply to black wire,brown wire to black/yellow(harness),white/brown to black/white(harness),white/black wire & red/black wire from black box go to resistor.
 
Have you tried swapping the coils (or coil wiring) over? Does the problem stay with the same coil?
 
I haven't tried swopping coils etc as I believe that as I only have 2v going to the r/hand coil & 9v to the left, the prob is going to be the black box/resistor or a high resistance between the box and the coil wire. It just seemed strange that I got the same reading(2v) from the load side of the resistor as I got from the coil wire. By the way on the box it says modified for 4S which I take is for cam profile.
 
hayabusaman0 said:
I haven't tried swopping coils etc as I believe that as I only have 2v going to the r/hand coil & 9v to the left, the prob is going to be the black box/resistor or a high resistance between the box and the coil wire.
Click to expand...

Yes, you're probably right, I can't find an AB5 wiring diagram as yet, so am working from your description of the wiring layout, and I can't explain the voltage readings so far.

hayabusaman0 said:
By the way on the box it says modified for 4S which I take is for cam profile.
Click to expand...

Yes that (Black case?) RITA system is meant for use with a 4S camshaft: http://www.eurospares.com/geninfo.htm
 
My RITA-equipped 750 is not up together at the moment so I can't make a comparison for you. If you're in the UK, it may be worth giving Al Osborn a ring. I believe that he now offers servicing of RITAs

http://www.aoservices.co.uk/

You're correct in your assumption regarding cam profile. The original RITA with the external pick-up was developed with the NV Race Shop and Mistral Engineering retained the ability to alter the advance curve dependent on the various cams. I had mine altered at one time for the PW3 cam.
 
Sounds like the Commando AB5 wiring ought to be the same or similar to this Moto Guzzi setup?: http://www.eurospares.com/graphics/lr124b.jpg

Which shows the coils wired in series and no coil earth wires?

One major difference is the Moto Guzzi is a negative earth system, so black wire goes to the ign. Sw. and not earth.
____________________________________________
[Edit](What is shown on the diagram as "existing 12V ignition feed wire would then be earth? So connects to only one coil + terminal?) please see later posting for more information.
 
The diagram is very faint, but it does look like that there are no earth wires to the coils, I'll remove the earth wire and see what happens, will let you know.

Paul.
 
hayabusaman0 said:
red(earth) to + on coils
Click to expand...


What is shown on the diagram as "existing 12V ignition feed wire" would then be earth? So is shown connecting to only one (Red/Black) coil + terminal?

hayabusaman0 said:
The diagram is very faint
Click to expand...

Click on the drawing for magnification.
 
Studying the drawing, and reading hayabusaman0's description of the wiring: "white/black wire from black box to - on l/h coil, red/black to r/h coil, red(earth) to + on coils," it would appear that the coils may be not be wired correctly if earth wires are connected to both coil + terminals, and no mention of any connection between coils 1 and 2 ?

Also it isn't clear which R/H coil terminal the Red/Black wire is connected to (+ or -)?

As Red/Black and earth wires should be sharing the same R/H coil (+) terminal, so what is connected to the R/H coil (-) terminal?
 
Hi L.A.B. thanks v. much for the drawing, I had the earth on the wrong connection(tosser) fired up 1st kick, just a bit of carb fine tuning to do. On a couple of other points I have no grease/oil nipple on the swing arm and I have noticed that 2 of the front disc mounting bolts(Norvil set up) are slightly proud of the disc and rub on the fork leg, I have read in the specs that a longer spacer is fitted to the Norvil set up, do you know the length that it should be or do I just shim it out(the disc is not central to the calipar either). Also how do I find out if it is tax exempt? It is an N reg with frame/eng no 320825 and date of reg is 04/01/1990.
 
hayabusaman0 said:
I had the earth on the wrong connection(tosser) fired up 1st kick
Click to expand...


Thanks for letting us know you got it sorted.




hayabusaman0 said:
I have no grease/oil nipple on the swing arm
Click to expand...

Your bike probably has the 'welch' plugs?

Does it also have the central swinging arm spindle retaining bolt? As it is possible to add EP140 oil (never use grease) through the bolt hole, I think?



hayabusaman0 said:
and I have noticed that 2 of the front disc mounting bolts(Norvil set up) are slightly proud of the disc and rub on the fork leg, I have read in the specs that a longer spacer is fitted to the Norvil set up, do you know the length that it should be or do I just shim it out(the disc is not central to the calipar either).
Click to expand...

Could you give some more information about that "Norvil" setup? Is it just a larger disc and a different caliper with a Norvil mounting plate? Or is it a Norvil hub? As the standard disc retainers are studs and nuts, not "bolts"?

hayabusaman0 said:
Also how do I find out if it is tax exempt? It is an N reg with frame/eng no 320825 and date of reg is 04/01/1990.
Click to expand...

To qualify for UK historic tax exemption, a vehicle would have to have been manufactured before 01/01/1973 (the actual registration date is unimportant) your bike would appear to be a fairly late 850 MkII, so would have been built around late 1974 (there should be a date stamp on the frame plate? If so, I'm sorry, it wouldn't qualify for free road tax.
 
The swing arm question could be due to using a Mk111 850 set- up. They had no nipples and were supposed to be sealed for life.

I put a Norvil front end together using Hemmings parts some years ago. Firstly, the disc should be central to the caliper for maximum braking efficiency. I too had clearance problems (do you mean between the alloy buttons which locate the disc on the carrier and the leg ?) I actually 'eased' the inside of the fork leg a fraction as the alternative was spacing the caliper away from the leg which seemed a bad idea. I suppose that I should have taken it back but I'd had the bits for several years before I used them.

You should have a Norvil style (alloy ?) spacer. I can't measure mine in-situ but it's much longer than the standard chromed item. It would certainly be worth getting your disc central then checking wheel alignment.

If your bike is an 850 it is not and never will be UK tax-exempt (unless they change the rules again).
 
Thanks for the reply, it is a pukka Norvil disc/leg/4 rib caliper. The spacer between the l/h fork leg (disc side) & wheel hub is a chrome item not alloy. Disc fixings are stud/nut. There is no swing arm central bolt.
I also had a quick measure of the front ISO, using a lever I am able to fit a .030" feeler gauge between the shims, this seems excessive, what do you think? Is there an article on here I can download on the way to check/adjust etc? I do have a Commando manual(genuine) & wonder if that is the best way to check/adjust?

Thanks, Paul.
 
hayabusaman0 said:
The spacer between the l/h fork leg (disc side) & wheel hub is a chrome item not alloy. Disc fixings are stud/nut.
Click to expand...

Sounds as if some or all of the studs are either too long, or not completely screwed in?



hayabusaman0 said:
There is no swing arm central bolt.
Click to expand...

So what setup do you have there? Does it have the long end plug retaining screw?
I would expect it to have either the central bolt or twin cotters?

Can you identify the setup from the ANIL parts drawings?: http://www.nortonmotors.de/ANIL/Norton% ... del=n850_2



hayabusaman0 said:
I also had a quick measure of the front ISO, using a lever I am able to fit a .030" feeler gauge between the shims, this seems excessive, what do you think? Is there an article on here I can download on the way to check/adjust etc? I do have a Commando manual(genuine) & wonder if that is the best way to check/adjust?
Click to expand...

Your genuine manual should mention the need to lever the front Iso. in order to check it, in section F13 ?
 
Is this a '75 (Mk3)? Does it have the rear disc brake? If it is then the the swingarm spindle is retained by two cotter pins and is supposedly lubed for life. There are felt discs and a felt plug in the center of the spindle which are soaked in oil. If you suspect the spindle is dry you can remove one of the welch plugs and pull the felts and soak them in 140wt oil and replace them using a new welch plug.

Preferred front Iso clearance is around 0.010". This can be adjusted slightly as preferred to fine tune vibration vs rpm. If you have a '75 Mk3 you have vernier adjustable isolastics which simply need a rod to fit the holes in the adjuster cap. If it is the earlier shim type, I find it easier to remove the front mount and take it over an mount it in a vise to check the clearance. Then I like to strip off the end caps, clean and regrease everything, replacing the plastic discs if necessary, then add the necessary shims to get the clearance I am shooting for, 1/2 on each side. Assemble everything in the vise, hold the head of the through bolt in the vise add washers at least as thick as the mounting tabs on the frame and torque the bolt to 25 ft/lb. and recheck the clearance.
 
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