What am I looking at?

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Any one that can do those diagnosis and repairs IS a hero of sorts using education and intellect. The magician would have a bulletproof new design that lasts forever.


I managed to figure out and draw out the circuitry, and knew what it was trying to achieve, it was my colleague who made the link to what happens in old style video projectors! (Military solutions...teamwork!)

I had already identified the advance curve when strobing it! Finding the jumper was a sort of relief on that one! I knew where the advance curve had gone.

Don't forget that back then most racers used points with AR unit welded up....so that it didn't explode like mine did! And that was why I fitted the Rita in the first place, to maintain an advance curve I thought was important, seems not when you push start the bike all the time!
 
To rehash an old story about timing advance on my new (then) 73 Chevy C-10 307CID automatic trans 3500 Lbs. pick up truck ( I was 23 years old).
Dealer said "you will never see 10 Miles Per Gallon".
By 50 thousand miles I had transformed the engine to 350CID Z28 camero high compression pistons, high compression heads but not big valves. low overlap RV cam, 2 barrel carb, headers balance pipe after headers, low restriction mufflers 2-1/2" exh pipes. 225-240psi cranking pressure.
Accel dual point distributor-full tuneable mechanical and vacuum advance.
I learned a tremendous amount about tuning the ignition from this
In the final result on one trip , from mississippi to north dakota, I got just short of 17mpg and on light cruise was advancing as much as 48 deg BTDC.
I was running 89 octane !!!
Yet in the last 6 years I have gone from 2 chainsaws to 64 (most given for free) and all the chainsaws, lawnmowers, weed wackers, blowers etc all run fixed timing around 24 +/-deg BTDC. A race motorcycle with a lot of cam overlap has lower cranking pressure and should start fairly easy.

In the mid 70's I also raced (autocross) an MGB and won 2 club year long championships in our X production class which is an open anything goes class.

Still being in the USAF and now a field instructor taught school based from Keesler AFB Miss. around the USA, England and Isreal the racing MGB program slowed down.
 
No spark when I click the ignition on and off. Tried connecting the two pick up wires, still no spark. Battery is brand spanking new and fully charged. Not quite sure how to measure the voltage on the lucas amplifier. I am looking at 6 wires coming out of the unit.

Kjell,

If you would like to make the AB5 system work, I have a box on the shelves surplus to requirements (missing the pickup bits). It's for free (+ postage). Send me a pm if you're interested.

-Knut
 
Case solved ( for now) Measured zero on the black lead that is supposed to give +12.8 over the ignition switch.
Connected directly to the battery and got spark. Reconnected the black and white from the ignition plate and seems to be working normally. Not impressed by the intensity of the spark but it will suffice from now. Startup tomorrow after 12 year in layup !!
 
The bike is a 72 commando roadster

The bike in your avatar if that is it, has a 20M3S engine which would make the engine earlier than 1972 (14-15xxxx).

For a '1972' model I would expect the engine, frame and gearbox to be in the 2xxxxx series.
 
The bike in your avatar if that is it, has a 20M3S engine which would make the engine earlier than 1972 (14-15xxxx).

For a '1972' model I would expect the engine, frame and gearbox to be in the 2xxxxx series.
Whoops !! It was bought in the US as a 72 Norton Commando Roadster and thats what all the paperwork says.
Not a big deal. Maybe DMV screwed up somewhere along the line
 
Actually I never checked numbers on the bike and here in Norway it is classified as a vehicle worth saving for historical purposes . The advantage is no inspections except the initial and next to nothing in registration/insurance
 
Whoops !! It was bought in the US as a 72 Norton Commando Roadster and thats what all the paperwork says.
Not a big deal. Maybe DMV screwed up somewhere along the line

Late year production bikes were often titled in the US as the following year when sold so it's nothing to worry about.

Just a matter of ordering the correct spares if it is a '15' series bike, therefore, the disc brake front end probably isn't original, and is that a steel fuel tank? If so then it's probably off a later model (850 Mk3?).
 
Late year production bikes were often titled in the US as the following year when sold so it's nothing to worry about.

Just a matter of ordering the correct spares if it is a '15' series bike, therefore, the disc brake front end probably isn't original, and is that a steel fuel tank? If so then it's probably off a later model (850 Mk3?).
Not worried at all. Actually the 71 has a better reputation then the 72 so I do not considered that a drawback, although the bad reputation of the 72 was mainly due to the introduction of the Combat as far as I have been able to find out. The gas tank is steel and was bought from Norvil since the original one was destroyed during transport from Salt Lake to Norway. The disk brake is a very sensible upgrade in my opinion although there are much better brakes on the market today (CNW)
 
The gas tank is steel and was bought from Norvil since the original one was destroyed during transport from Salt Lake to Norway. The disk brake is a very sensible upgrade in my opinion although there are much better brakes on the market today (CNW)

Yes, I was just wondering if you knew that's all. :)
 
One down- one to go.

Thanks to all the members of this forum for the help and response I have been getting. This problem was solved in no time due to the very knowledgeable people on this forum. Most forums now a days are just full of bs and personal attacks. Glad to find one that actually works as intended.
Now off to find out why the bike doesnt charge. I guess I will be riding by the middle of next week anyway !!:):):)
 
@Kjell great to hear you are up and running - and apologies for a thread full of rudeness, aggression and ego flexing.
I promise it’s not always like that on here, so please don’t be put off!


For charging, make a start by looking at the regulator/rectifier (the shiny thing with the cooling fins).
Check that all the connections that go to it are sound and secure, that there is no wire chaffing as they pass through holes and that the unused wires to the old zener and capacitor (if that has been removed) are safely taped up and cannot touch the frame.

There is an article on my site that walks you through testing your regulator/rectifier:
https://granttiller.com/testing-your-motorcycle-rectifier

If found faulty, these are easily replaced with a new one.



@dynodave it seems like my post #45 was the one that tipped you out of your pram - sorry for that.
My learnings on the Boyer Bransden Micro MarkIII were based on our own 1976 MKIII Commando which ran like a bag of spanners when we got it, due to the Boyer Bransden Micro MarkIII that the previous owner had fitted to the bike.
I have also tested and made good ones out of bits from a Combat engined bike and a Triumph Bonneville.
I didn’t feel the need to credit you for that.
 
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For charging, make a start by looking at the original rectifier.

Post #8, shows it has a reg/rec.
 
@Kjell I updated my site to cover the Lucas RITA AB5 today, as I only had the AB11 covered previously.

While I was in drawing mode, I put a wiring diagram together for your bike:


Let me know if there are any tweaks or changes you need!
 
@Kjell I updated my site to cover the Lucas RITA AB5 today, as I only had the AB11 covered previously.

While I was in drawing mode, I put a wiring diagram together for your bike:


Let me know if there are any tweaks or changes you need!

@gtiller.
I did not believe my eyes when I saw what you did. Words doesn't cover it !! Thaaank you !!
Since I have a feeling I am only scratching the surface on the wiring on this bike help like this is of immense value to me.
I was in the garage a couple of hours last night and tried a few things. It turns out there was not a simple solution as I was hoping for.
Seems like I have to rip up the wiring completely to find the culprit
Thanks again
 
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