Mk3 starter issue.

Hi Gents,
recently rebuilt my mk3 . when reinstalling the primary side inc starter parts I decided not to change the sprag as i didn’t know if it was ok or not, bu it looked fine. The starter is upgraded 4 bush with upgraded leads.
on completion it all worked very well for the first 800 miles and many many starts. Then, it started to spin with a whirring sound but not turn the engine,it would turn it though occasionally. No worries I thought ,strip it and change the sprag. When I removed the primary cover the rotor nut was off , I had torqued it but not thread locked it ,I assumed this may be to blame. As I had already purchased the spa rag from AN I decided to change it anyway although the old one still looked ok. I torqued it all up again with thread lock and before refitting the cover tested it.All seemed fine and on a number of further starts it started straight away. Today I rode it for the first time, stopped for a coffee after about 60 miles. When I tried to restart it it just whirred again. I can see through the timing hole that the rotor nut is fine. Both sparags were the 18 bearing type. Any ideas what else it could be please?
Thanks .

Was your anti-backfire device checked for proper torque setting?

Oil to thick?
Contamination from fiber type clutch plates? (barnett) act like grease under the dog bone rollers and inhibits engagement. (still in research)
Dimpled race on drive gear? very tiny damage from dog bone impacts.
Slightly undersize drive race (from new) makes low contact pressure and prevents engagement. STS and AN were reported to fix this undersize in their new releases.

grandpaul said:

Was your anti-backfire device checked for proper torque setting?

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No it wasn’t,to be honest, I’d never heard of that until recently. How do I do that?

JOHNO23 said:

How do I do that?

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grandpaul said:

Was your anti-backfire device checked for proper torque setting?

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Ooooh, no

L.A.B. said:

Old Britts, Overload backfire device assembly and adjustment

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Cheers L.A.B.

"Please note, if you need to replace any of the following, you will need to replace ALL of the following at the same time:-
Sprag Clutch (064733)
Sprocket (064681)
Gear Assembly (064731)
The reason for this is that they all wear at the same rate and failure to replace them together often leads to premature failure of the new part"

If the anti-backfire device slips at any time then you are unlikely not to hear it as it makes a loud clattering noise.

L.A.B. said:

Norvil Motorcycles - Product Photo

www.norvilmotorcycle.co.uk

"Please note, if you need to replace any of the following, you will need to replace ALL of the following at the same time:-
Sprag Clutch (064733)
Sprocket (064681)
Gear Assembly (064731)
The reason for this is that they all wear at the same rate and failure to replace them together often leads to premature failure of the new part"

If the anti-backfire device slips at any time then you are unlikely not to hear it as it makes a loud clattering noise.

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Go to the CNW site and $pend. Super hardened components and a better 14 roller cage sprag.

dynodave said:

Oil to thick?
Contamination from fiber type clutch plates? (barnett) act like grease under the dog bone rollers and inhibits engagement. (still in research)
Dimpled race on drive gear? very tiny damage from dog bone impacts.
Slightly undersize drive race (from new) makes low contact pressure and prevents engagement. STS and AN were reported to fix this undersize in their new releases.

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That would make sense. As soon as I cleaned it all up it turned the engine easily.
It was mucky when I opened it all up. I assumed perhaps it was due to the rotor nut rubbing and leaving some debris. I have fitted fibre clutch plates.
so maybe change the drive race and use thinner oil. What oil would people use?I had 20/50 in it.

JOHNO23 said:

What oil would people use?I had 20/50 in it.

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If you use a thinner oil in the Mk3 primary then the hydraulic tensioner might not work properly.

L.A.B. said:

If you use a thinner oil in the Mk3 primary then the hydraulic tensioner might not work properly.

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Bugger!........I was always under the impression that the hydraulic tensioner didn’t actually work anyway..... not sure what to do now...

OK now who has bothered to bring up the gearbox oil contaminating the primary lubrication?
10 posts?
20-50 oil
or
20-50 + cold 90W after a stop?
Post #3 first statement "oil too thick"
Do you have a clutch rod seal?
Contamination from fiber type clutch plates? (barnett) act like grease under the dog bone rollers and inhibits engagement. (still in research)
Some people say you don't need one? Yet they don't run a MKIII.

JOHNO23 said:

It was mucky when I opened it all up. I assumed perhaps it was due to the rotor nut rubbing and leaving some debris. I have fitted fibre clutch plates.

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Being a skeptic, I don't put much stock in any of the quoted sources.
My plan of action for my e-start bikes would be, have a real expert (LOL) :

#1 inspect drive race for dimple damage or being under size
#2 inspect engine sprocket for dimple damage (much less likely) or being over size
#3 inspect sprag dogbones for wear on the ID end. These are the end constantly rubbing while the engine runs. Look for flatening or satin gray wear as evidence . The spring cage is also tender and can inhibit dogbone engagement in this 3 piece system.

#4 install CCRS @ norvil
#5 wash bronze friction and steel clutch plates I would avoid fiber .

Self help in this area is difficult when the "help" from the outside is hand grenade $ or thermonuclear bomb $$$$$ in nature, rather than engineering in nature.

JOHNO23 said:

I was always under the impression that the hydraulic tensioner didn’t actually work anyway....

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Well, it should work.
There can be reasons why it doesn't but if it wasn't working then you'd be likely to notice it at low engine speeds.

As mentioned, the sprag tracks wear, increasing the clearance and a new sprag alone is unlikely to fix the problem for long. As the sprag appeared to be slipping before you replaced it, then it could be the problem. I've never known the sprag to slip using 20w/50 oil.

Fitting the dynodave clutch rod seal is a good suggestion if not done already.

dynodave said:

Contamination from fiber type clutch plates? (barnett) act like grease under the dog bone rollers and inhibits engagement. (still in research)

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That seems to have been "still in reasearch" for some time now.

L.A.B. said:

That seems to have been "still in reasearch" for some time now.

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True, but what's your point? I get data when people approach me rather than reap and propagate internet rumor and propaganda like keyboard commandos. I hold examples of components that are failing and try to realistically come to some conclusion.

L.A.B. said:

As mentioned, the sprag tracks wear, increasing the clearance

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This is the first on this for me...
Any quotable source? Wear and track dimpling have the exact opposite effect of each other.
Wear makes the ID bigger and OD smaller.
Dimpling will raise the average surface peaks the same affect as knurling. That makes an ID smaller and an OD bigger.

L.A.B. said:

is unlikely

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L.A.B. said:

it could be

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I agree IMO, an across the board final conclusion would be premature.

Using ATF in the primary will promote chain clatter until the hydraulic tensioner gets its prime (i.e. ATF drains from the tensioner too quickly) clatters at the first start of the day and then fine until the next cold start.
I sleeve the drive gear to close the clearance up and far cheaper than wholesale replacement of sprocket,sprag and drive gear. But first inspect the drive gear,sprag, sprocket (assembled without the large washers) and look at the dogbone angle through the sprocket puller holes.
If the dogbones are almost vertical (following a radial line from the center of the sprocket, the sprag is in danger of crunching. They should be at an angle of 20-30 degrees from the radial line.
There are a few different sprags available or have been available, 14 or 18 ones, German, UK and chinese made . Some have additional spring cage bits and different cage assemblies. i haven't got any info on which ones are the most reliable (mores the pity)
If using bronze clutch plates and you are getting clutch slip, this can be addressed by machining 1/4" from the inside of the bronze face on both sides of each plate. Also much cheaper than plate replacement.
Johno23 Where in the UK are you? i'm in yorkshire

dynodave said:

True, but what's your point?

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My point was that so far it seems no more than a theory with no evidence there's an actual problem.

dynodave said:

This is the first on this for me...
Any quotable source? Wear and track dimpling have the exact opposite effect of each other.

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I quoted from the Norvil web page:
"The reason for this is that they all wear at the same rate and failure to replace them together often leads to premature failure of the new part"
Shouldn't dimpling also be classed as a form of 'wear'? Personally, I haven't noticed any such dimpling on either track.


Sprags are known to flip over which suggests clearance increases.

dobba99 said:

Using ATF in the primary will promote chain clatter until the hydraulic tensioner gets its prime (i.e. ATF drains from the tensioner too quickly) clatters at the first start of the day and then fine until the next cold start.
I sleeve the drive gear to close the clearance up and far cheaper than wholesale replacement of sprocket,sprag and drive gear. But first inspect the drive gear,sprag, sprocket (assembled without the large washers) and look at the dogbone angle through the sprocket puller holes.
If the dogbones are almost vertical (following a radial line from the center of the sprocket, the sprag is in danger of crunching. They should be at an angle of 20-30 degrees from the radial line.
There are a few different sprags available or have been available, 14 or 18 ones, German, UK and chinese made . Some have additional spring cage bits and different cage assemblies. i haven't got any info on which ones are the most reliable (mores the pity)
If using bronze clutch plates and you are getting clutch slip, this can be addressed by machining 1/4" from the inside of the bronze face on both sides of each plate. Also much cheaper than plate replacement.
Johno23 Where in the UK are you? i'm in yorkshire

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Cardiff.......

The dimpling is not supposed to be there, use a new engine sprocket made from tougher material and deeper case hardening. You can case harden a creme brulee, but it still does not work. The original MK3 engine sprockets were the same spec material as the pre MK3 and thus not tough enough.

dobba99 said:

Using ATF in the primary will promote chain clatter until the hydraulic tensioner gets its prime (i.e. ATF drains from the tensioner too quickly) clatters at the first start of the day and then fine until the next cold start.
snipped

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The factory has added a gasket between the alloy tensioner housing and the sheet steel outer plate. The idea being to prevent/slow leakage of oil from the reservoir formed by the back wall of the inner chain case, the alloy body and the sheet steel plate. Use of a sealant or a 2nd gasket between the inner chain case and the alloy plunger body would also help keep the reservoir filled and the tensioner primed.

Tensioner gasket

This part is not in the factory parts catalog. It was added after the fact.

chaztuna said:

The idea being to prevent/slow leakage of oil from the reservoir formed by the back wall of the inner chain case, the alloy body and the sheet steel plate.

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The back wall of the inner chaincase doesn't form part of the reservoir.