Starting cafe racer restoration Commando 850 MK3 from Spain

Here the pics.
 

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Today I easily dismounted the alternator, the alternator support plate, the rotor and finally I reached the e-start gears to find out was was wrong to make the starter motor spin freely not engaging the crankcase.
I took off the starter drive big gear from the crankcase and checked the starter sprag bearing clutch. I think the problem is here because when I took the sprag bearing on my hand and made it turn it did it both clockwise and counter-clockwise. I also assembled it again and turned the starter gear with the same result, it freely turns in both directions.
Checking out the sprag bearing I realize it is not perfectly round but it is a bit offcenter, find some pictures, on the left hand is visible that it is off center when installed into the gear (that I checked with an electronic gauge that is perfectly round inside).
 
Here the pictures
 

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I have another question, when I disassembled the alternator support plate I did not see not any dowel or pin number 19 on Norton Andover drawings ref. 06.7621.
I do not know what is this dowel for and where should it be mounted.
Find the the drawing.

I also would like to know if I need to replace the rotor washer number 30 or I can just use again the actual one.
 

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javifoto70 said:
Here the pictures
Click to expand...

The starter sprag assembly should pull off the gear?
The sprag 'rollers' appear to be laying over more than normal and maybe in the wrong direction so that could be why it is slipping.
andover-norton.co.uk

Motorcycle parts and spares for Norton motorbikes - Genuine Andover Norton Spare Parts - Andover Norton Motorcycles Parts - Original Andover Norton Parts

Motorcycle parts and spares for Andover Norton motorbikes: Andover Norton manufactures and supplies all Genuine Factory Spare Parts for Norton motorcycles built before 2002.
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javifoto70 said:
I have another question, when I disassembled the alternator support plate I did not see not any dowel or pin number 19 on Norton Andover drawings ref. 06.7621.
Click to expand...

The dowel pin 19 locates the stator outrigger to the inner primary case and is easily lost.

javifoto70 said:
I also would like to know if I need to replace the rotor washer number 30 or I can just use again the actual one.
Click to expand...

You can reuse it but better to replace it if possible.

Unrelated to the starter problem but the primary chain looks worn out (the lower run should not be in contact with the primary case) or the tensioner plunger abutments are fitted incorrectly (the head of the abutment should be against the spring)...

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...or the plunger springs are weak (or any combination of the three).
 
I tried to mount the sprag in both directions with the same result, it keep spinning both clockwise and counter-clockwise. And it behaves like that both assembled into the gear or stand alone.
On one of the pictures the sprags appear to be laying over more than normal but I did it on purpose just on the picture for you to see how the sprag bearing is off center.


Do you mean I need to buy a dowel and fully insert it into the stator outrigger little hole located on the left hand side.
 

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javifoto70 said:
I tried to mount the sprag in both directions with the same result, it keep spinning both clockwise and counter-clockwise. And it behaves like that both assembled into the gear or stand alone.
Click to expand...

When assembled if worked by hand then the sprag should lock the drive gear to the crank when turned counterclockwise.

javifoto70 said:
Do you mean I need to buy a dowel and fully insert it into the stator outrigger little hole located on the left hand side.
Click to expand...

Yes, as the dowel should be there. The hole in the outrigger needs to be peened to prevent it from dropping out.

javifoto70 said:
And how do I check the primary chain wear down?
Click to expand...

You need to measure the chain wear over a certain length, preferably after it has been removed from the primary case and also check the tensioners are assembled correctly and that the springs are still in good condition, however, it would probably be better to replace them especially if they do not sufficiently tension the chain when "static".

Edit: The teeth of the engine sprocket and clutch chain wheel could be worn so may also be contributing to the slackness of the chain.
 
Last edited:
Looking at that sprag gear, it doesn't even look like a Norton one to me, or are my eyes going??

The 'rollers' just look a totally different shape??
 
With the sprag assembly fitted into the crank (engine sprocket) and without the starter drive gear then the sprag rollers should be leaning this way:
Starting cafe racer restoration Commando 850 MK3 from Spain
 
Further observations from the pictures are that the stator would normally be fitted with the wiring entry on the outside...
Starting cafe racer restoration Commando 850 MK3 from Spain

Ordinary washers or lock washers have been used instead of the normal outrigger stud/nut tab washers...
andover-norton.co.uk

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Motorcycle parts and spares for Andover Norton motorbikes: Andover Norton manufactures and supplies all Genuine Factory Spare Parts for Norton motorcycles built before 2002.
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...and the outrigger studs appear to have been drilled or perhaps they're not the normal studs.

The clutch pushrod adjuster seems to be screwed out more than I would expect.
 

DC 4127 sprag from AliExpress (2019)

I hope everyone who ordered has received one. My 2 showed up last week. They appear to be the same as the last one. That sprag has done 150 or so starts now, no issues. The minute I hear any slippage is when the old will come out and a new $17 unit will go in. The $180 Norvil unit lasted about a...
www.accessnorton.com www.accessnorton.com

However, if the internal engine sprocket and external drive gear bearing tracks are worn then a new sprag alone might not cure the problem if it's tipping over. The sprag is also the later 18 'roller' (14 originally) type.
 
Since I have not been able to make the sprag bearing work I already ordered the Aliexpress one, I hope it won´t be necessary to change also the starter drive gear (06.4731) neither the engine sprocket (06.4681).

After disassembling every gear and part into the primary case I found the chain is strangely slacken and long. I will have to buy a new one but do I have to buy also a new engine sprocket and a clutch basket?
 

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What about the tensioner pads? Do I have to replace them?
 

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Since I will have to remove every part into the primary transmission I am considering updating also the secondary chain and maybe the rear wheel sprocket (I hope not), what do you think about it?
 

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javifoto70 said:
After disassembling every gear and part into the primary case I found the chain is strangely slacken and long. I will have to buy a new one but do I have to buy also a new engine sprocket and a clutch basket?
Click to expand...

Concerning the chain then that depends on how badly the sprocket teeth are worn but for sprag operation also wear of the bearing surface of the engine sprocket so may need changing regardless of tooth wear.
 
javifoto70 said:
What about the tensioner pads? Do I have to replace them?
Click to expand...

Not necessarily, you would have to replace the plungers as the pads are not available separately.

Also, you should have found a white nylon 'abutment' inside each plunger with the wide end to the spring.
andover-norton.co.uk

Motorcycle parts and spares for Norton motorbikes - Genuine Andover Norton Spare Parts - Andover Norton Motorcycles Parts - Original Andover Norton Parts

Motorcycle parts and spares for Andover Norton motorbikes: Andover Norton manufactures and supplies all Genuine Factory Spare Parts for Norton motorcycles built before 2002.
andover-norton.co.uk

There should be a gasket between the tensioner body and the outer steel plate.
andover-norton.co.uk

Motorcycle parts and spares for Norton motorbikes - Genuine Andover Norton Spare Parts - Andover Norton Motorcycles Parts - Original Andover Norton Parts

Motorcycle parts and spares for Andover Norton motorbikes: Andover Norton manufactures and supplies all Genuine Factory Spare Parts for Norton motorcycles built before 2002.
andover-norton.co.uk

javifoto70 said:
Since I will have to remove every part into the primary transmission I am considering updating also the secondary chain and maybe the rear wheel sprocket (I hope not), what do you think about it?
Click to expand...

There's still some life left in that rear sprocket. I don't know about the chain or front sprocket.
 
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