MkIII Electric Leg Questions

It is odd then that the AN photo overlay states 18 sprag will not work with the 14 sprag associated parts. Maybe there is something special with their specific 18 sprag? I thought these things are generally used in other machinery and are somewhat standardized?

After the Norvil sprag let go I called them thinking there might be a warranty period and that it might be greater than 24 hours.
That turned out to be wishful thinking as Les informed me that all of the components must be replaced every time or failure will definitely occur.
I recall that the sprag alone was just under $200 cdn landed here and the other parts were about 6 or 700. I decided it would be better to kick start the thing that spend another grand on something that might let go in hours.
Not long after that someone posted that they had replaced the entire gubbins with the new Norvil items and the sprag still let go in a very short time.
So I decided to forget the estart for a few years.
At some point Matt at CNW mentioned that they were looking at making uprated drive parts for the MK3.
I would have gladly gone for those items however it took awhile for them to become available.
In the meantime I noticed the cheap Sprags on AliExpress and thought it worth a try for such a small sum. My inner and outer drive surfaces on the original parts were pretty beat up, but still measured ok. So cheap sprag and old beat up parts that "must be replaced with the sprag " are still working well.

If that hadn't worked I would have installed the CNW items, and still might at some point.
If your friend doesn't mind wrenching, I would try the cheap sprag in there without changing anything else.
If that doesn't work, get the CNW stuff.

Glen

worntorn said:

After the Norvil sprag let go I called them thinking there might be a warranty period and that it might be greater than 24 hours.
That turned out to be wishful thinking as Les informed me that all of the components must be replaced every time or failure will definitely occur.
I recall that the sprag alone was just under $200 cdn landed here and the other parts were about 6 or 700. I decided it would be better to kick start the thing that spend another grand on something that might let go in hours.
Not long after that someone posted that they had replaced the entire gubbins with the new Norvil items and the sprag still let go in a very short time.
So I decided to forget the estart for a few years.
At some point Matt at CNW mentioned that they were looking at making uprated drive parts for the MK3.
I would have gladly gone for those items however it took awhile for them to become available.
In the meantime I noticed the cheap Sprags on AliExpress and thought it worth a try for such a small sum. My inner and outer drive surfaces on the original parts were pretty beat up, but still measured ok. So cheap sprag and old beat up parts that "must be replaced with the sprag " are still working well.

If that hadn't worked I would have installed the CNW items, and still might at some point.
If your friend doesn't mind wrenching, I would try the cheap sprag in there without changing anything else.
If that doesn't work, get the CNW stuff.

Glen

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Yes this is what I've suggested as best path forward. I have sent him a list of recommended parts from AN (gasket, seals, gear pedal shaft bushing, tabbed washers for stator, shake proof washer for rotor nut) and a link to the Aliexpress sprag.

The gb kicker issue is a whole other mess of worms, not sure I want to get into it on his shed floor.

Just throwing this out.
Has anyone here or heard of an Ali Express sprag letting go?

I ask that question every now and then. Iirc there was one that had failed last time I asked. There appeared to be quite a few out there working well from the responses.

Glen

I had Mark 3 20+ years ago. Didn't have any sprag problem as the motor was to week to spin it cold.
So I took the starter and little gear off, blanked it out and rode.
Left all the other paraphanelia in there. Always though it was complicated.
Put the starter back on when I sold it so he could have it.

Two questions.
1. Parts 7,8,11,and 12. What is there purpose? Some kind of shock absorbtion?
2. After replacing all the parts in the plunger assembly, I still had the off idle primary cackle.
To fix/minimize it, I turned the idle up. I often wondered if a new Primary chain would have solved it.
The bike did have 25k miles on it. Would a chain have fixed it, or this is a normal condition?

MichaelB said:

Just throwing this out.
Has anyone here or heard of an Ali Express sprag letting go?

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Mine x 2, Ali express Sprags did not "let go" but the ends of the dogbones flattened out and the sprag failed to grip on the inside of the engine sprocket. Prior to this it should be noted I had the inside of the engine sprocket machined out and a hardened bearing race/sleeve fitted and machined to spec. When the sprag failed all it did then was make a whirring sound as spun round not turning the engine over. I have since stumped up for the CNW MK3 Starter kit.Although initialy it was great but twice recently it has slipped when on a cold start it did then start,but hot is perfect,just need to touch the button and the engine bursts into life.

MichaelB said:

I had Mark 3 20+ years ago. Didn't have any sprag problem as the motor was to week to spin it cold.
So I took the starter and little gear off, blanked it out and rode.
Left all the other paraphanelia in there. Always though it was complicated.
Put the starter back on when I sold it so he could have it.

Two questions.
1. Parts 7,8,11,and 12. What is there purpose? Some kind of shock absorbtion?
2. After replacing all the parts in the plunger assembly, I still had the off idle primary cackle.
To fix/minimize it, I turned the idle up. I often wondered if a new Primary chain would have solved it.
The bike did have 25k miles on it. Would a chain have fixed it, or this is a normal condition?

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Andover Norton Parts are the only Norton spare parts in the market manufactured to original drawings, within the factory-approved tolerances, from the correct materials, and with the correct finish.

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Those parts form the anti-backfire device, which I gather helps protect starter drive from shock load if backfire occurs while operating.

By plunger, I assume you mean the hydraulic chain tensioner? I was studying a mk3 primary chain case rebuild video and the guy mentioned a common mistake is to place the "plunger" spring plastic end caps the wrong way around. The longer, smaller diameter end can slide inside the spring so that is what some people do. Correct fitment is long smaller diameter end point down the bore away from the spring. Getting that wrong means no chain tension and a constant clatter. Also, the tiny holes in the plastic caps, the pistons and housing bores all need to be free flowing. The check valve ball bearing needs to be free to rattle when cleaned out.

That is what caused my failure, the top hat spacers had been put in the wrong way round. The spring had less tension, the chain remained loose. It wore a groove on the chain case. The swarf formed a grinding paste. The tensioner stuck in on one side, the chain got even looser. More grinding paste. The sprag failed and the primary oil was very pretty, filled with glitter. All in just under 3,000 miles.

Edit: Just remembered, the sprag had been replaced with a Norvil one, just before I bought the bike. So it failed within 200 miles because of the chain drag sludge, but also, no receipts for any other parts being replaced at that time.

Tornado said:

Those parts form the anti-backfire device, which I gather helps protect starter drive from shock load if backfire occurs while operating.

By plunger, I assume you mean the hydraulic chain tensioner? I was studying a mk3 primary chain case rebuild video and the guy mentioned a common mistake is to place the "plunger" spring plastic end caps the wrong way around. The longer, smaller diameter end can slide inside the spring so that is what some people do. Correct fitment is long smaller diameter end point down the bore away from the spring. Getting that wrong means no chain tension and a constant clatter. Also, the tiny holes in the plastic caps, the pistons and housing bores all need to be free flowing. The check valve ball bearing needs to be free to rattle when cleaned out.

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Yes, I fought it. I believe I eventually had it right. Who knows, 20 years ago.
Needed a higher idle to prevent the Clackety clack. Don't remember the RPM number, not excessive, but higher.
Let us know how it comes out.

Here is the video I've been studying, quite a detailed rebuild of the mk3 primary...part of a larger series on a whole mk3 rebuild.

So I was back at the mk3 bike today to fit the new Ali express sprag.Eventually got it all in there ok. Lots of time went by messing with a badly worn shifter bush in outer cover. Turned out cover had been welded to repair a crack horizontally rearward from the shifter opening. A very big, ugly donut of weld inside around the opening,and a big steel washer stuck/welded? to the blob to support the bronze bushing. Seemed like Bush worn on the shaft, sloppy, but also able to spin in the cover hole, so likely worn there too. New bushing fit both cover and shaft much better, but not full held in cover. As there an oil drainage hole in bush to align to hole in welded blob, decided to secure new bushing with some
Locktite against cover hole side.


So after everything back on except outer cover, we tested the starter....SAME BLOODY WHIRRING BUT NOT TURNING ANYTHING!
Starting to think someing else wrong inside starter...but then I asked again. Is battery charged? He has told me earlier new battery (3-4months) and he charged and rode a half dozen times before no cranking issue. Ok so I asked to see charger...well turns out it was a booster starter, not an actual charger! Tested battery volts, 9.2v!!!
Attached booster, and everything spun up nicely as expected. So looks like his battery was original problem. Not sprag. Told him to get a real charger to try to recover battery. Told him how to confirm rec is rectifying and zener's are holding max volts to under 15.5v.

We'll see what happens...

Tornado said:

So I was back at the mk3 bike today to fit the new Ali express sprag.Eventually got it all in there ok. Lots of time went by messing with a badly worn shifter bush in outer cover. Turned out cover had been welded to repair a crack horizontally rearward from the shifter opening. A very big, ugly donut of weld inside around the opening,and a big steel washer stuck/welded? to the blob to support the bronze bushing. Seemed like Bush worn on the shaft, sloppy, but also able to spin in the cover hole, so likely worn there too. New bushing fit both cover and shaft much better, but not full held in cover. As there an oil drainage hole in bush to align to hole in welded blob, decided to secure new bushing with some
Locktite against cover hole side.


So after everything back on except outer cover, we tested the starter....SAME BLOODY WHIRRING BUT NOT TURNING ANYTHING!
Starting to think someing else wrong inside starter...but then I asked again. Is battery charged? He has told me earlier new battery (3-4months) and he charged and rode a half dozen times before no cranking issue. Ok so I asked to see charger...well turns out it was a booster starter, not an actual charger! Tested battery volts, 9.2v!!!
Attached booster, and everything spun up nicely as expected. So looks like his battery was original problem. Not sprag. Told him to get a real charger to try to recover battery. Told him how to confirm rec is rectifying and zener's are holding max volts to under 15.5v.

We'll see what happens...

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good sleuthing!

jan nelder said:

good sleuthing!

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Well, not so great....seems my assumptions "made an Ass out of U and Me" as the saying goes ;-)
Shoulda checked voltage first. Also trying starter after cover off before more wrenching would've been informative.

Lessons learned!

Question for you electric leggy types, how does the neutral lamp work, where is the switch for it? Does it prevent starter ops when not in neutral like moderns? This bike had no neutral light on when GB in neutral.

Switch is on bottom of gearbox…06-5390…fits through the gearbox to a “button” on the camplate …maybe out of adjustment. It does not effect the starter engagement
Rod

Britbike850 said:

Switch is on bottom of gearbox

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Front face of the gearbox.

Britbike850 said:

Switch is on bottom of gearbox…06-5390…fits through the gearbox to a “button” on the camplate …maybe out of adjustment. It does not effect the starter engagement
Rod

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Thx. Will investigate. First check will be for blown bulb or bad connection.

Update on this. Bike is now running again after a good charge on the battery.

Still needs the KS fixed and owner didn't want to mess around with the throttle grip friction adjuster at this point. We put some wd40 around the twist grip and it did loosen a little bit.
I'll be doing a ride with him in next few days to see how it goes.

A couple of Preventive Maintenance items on factory E-start:
1) regular primary oil changes will save the sprag and chain from wear.

2) When servicing the e-start, check the anti-backfire device torque as per the manual -- 50 ft. lbs IIRC.

3) Make sure the battery voltage is up to snuff. If you have a Boyer ignition or any other ignition prone to advancing at low voltage, the engine will backfire on start-up. If the anti-backfire device doesn't let loose and the sprags flip over, when the engine fires and you rev it you will hear a high-pitched whine growing ever higher with RPM until the starter motor armature explodes inside its case. You will then need a hydraulic press to get the armature out of the housing. But better just look for a 4-brush Prestolite starter and use the field assembly after you press the armature out of the case and have it re-wound.

Don't let the sprags flip over!
Check the torque on the anti-backfire device!

I have been able to recover from such events because I saved back junk starter parts that we removed from various MKIII bikes.

I also replaced the sprag in an e-start Enfield Bullet with 18-sprag units (twice) and they worked fine until the owner let the battery run down and tried to start the bike with electronic ignition. The Royal Enfield single has no anti-backfire device. The third time the sprag surfaces were badly torn up and it was prohibitively expensive to fix so I took all the starter gears etc. out and told the owner he'd just have to learn to kick start it.