Mk 3 Primary noises

:roll: I have recently purchased a MK3 Commando started it yesterday for the first time , it started with the starter , great I thought then stoped . Went to restart had a backfire now when it starts , a little rev and the primary sounds like gears spining up not nice . Has any one got a sugestion , could it be the sprag has spun inside out , thanks Norton Dave .

Welcome Dave,

I suggest you remove the primary cover and check if the starter drive is disengaging or not?

http://www.oldbritts.com/e_start_gears.html

Norton Dave,
If the sprag is not the culprit: What you hear is probably is a hydraulic chain tensioner drained of oil. If the bike was left standing for a long time the chain tensioner, normally refilled by oil splashed in by the top run of your primary chain, has lost its oil. The oil serves as the hydraulic "cushion" between the two pistons of the tensioner, and this gets automatically refilled when the distance between the pistons gets bigger as the chain wears.
The chain tensioner has a paper gasket 06-6570 behind it which is not illustrated in the Mk3 parts list though listed in the text, hence tends to be left out by restorers/repairers. This lets the oil out pretty quickly.
Also, the whole assembly relies on the ball valve seating correctly. As the chain, sprockets etc wear the oil gets dirtier and metal residue tends to stop the ball valve from seating properly, thus lets the oil get out again and effectively sabotages the "cushion" effect.
I recommend to open the chaincase, clean the tensioner, put it on using the gasket towards the inner chaincase, priming it before you put the outer chaincase cover back on by filling oil into the "trough" of the tensioner and pumping the two pistons against eachother until they can not be moved against eachother any more. Then put the outer cover on and refill with the recommended amount of primary oil- I use Shell Donax TX, keep away from multigrade engine oils!- and start it up.
I am pretty certain the ugly noises will have gone. When you have the primary open look if the chain has rubbed on it- that was your ugly noise.

ZFD said:

keep away from multigrade engine oils!

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I must admit I don't entirely agree.
After using various types of ATF in my Mk3's primary chaincase it was suggested to me that I might try engine oil-which I did, first I tried 10w/40, and it seemed to make a noticeable improvement to the tensioner operation resulting in less low speed primary chain snatching and reduced the initial tensioner knocking after starting.
I then tried 20w/50, which further improved tensioner operation. The primary drive seemed to run quieter too-and it caused no adverse affects to the clutch or electric starter mechanism-so personally I'm content to continue using 20w/50.

I have to admit I sold my Mk3 Commando in about 1980 and haven't run one since. However, Multigrades tend to have additives that are graphite based, which make very clutch slip, so if one insisted on engine oil I would use a Monograde. The ATF has done its job nicely in all our Commandos, road and race (we race the standart chain primary drive) in the last thirty years or so. ATF oils are available to various specs, and I have encountered some that didn't work at all, hence my naming the oil that has given us good results.

ZFD said:

Multigrades tend to have additives that are graphite based

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I'm not sure that is correct?

ZFD said:

which make very clutch slip

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My Mk3 Commando has a standard bronze plate clutch and it doesn't slip with 20w/50-at all (the only odd time I do remember it slipping was when I used ATF in the primary!)

Graphite= Molybdendisulfid (German term, my English does not extend to chemistry). They do. Rev it to 7 and see what the clutch does. Or, worse, pump about 50% more bhp than a standard production Mk3 through it and 80nm torque and see what the clutch then says.
As I said, I had unfortunate experiences with other ATFs, so don't claim they all work.

ZFD said:

Graphite= Molybdendisulfid (German term, my English does not extend to chemistry).

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As far as I'm aware Graphite isn't Moybdenum Disulphide/Disulfide????

http://en.wikipedia.org/wiki/Molybdenum_disulfide
http://en.wikipedia.org/wiki/Graphite


Also, I contacted the techical department of Miller's Oils and asked them if graphite was a standard motor oil additive and did they use it?

The reply I received was that: none of their engine oils contained graphite and they were not aware of any other major oil company that added graphite to their engine oil.

http://www.millersoils.net/

ZFD said:

Rev it to 7 and see what the clutch does.

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Why only 7(000) ? :?

I don't get it why revving to 7000rpm or 6000 or anything would matter.

The clutch and plates are DRY and are supposed to be.

If we are talking about what kind of oil lubes the primary chain, then that oil has nothing to do with the clutch, unless one assumes that their own clutch and plates are constantly contaminated with primary fluid, not good maintenance.

So why would revving the motor or adding more horsepower or torque have anything to do with what kind of oil
goes in the primary, as regards the clutch and plates?

1up3down said:

The clutch and plates are DRY and are supposed to be.

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How can the Commando clutch be "dry"?

The clutch assembly is in the primary case-not in a separate compartment. The assembly is open and not sealed from the primary oil, the clutch basket even has holes to allow the oil to escape. Run a dry clutch under those conditions and it wll soon be a wet clutch.

If you take a clutch apart that has been run on any common multigrade you find a black deposit in the grooves of the clutch friction plates- the residue of the additives that the oil left that does supposedly not get into the "dry" clutch. The clutch is "dry" only theoretically, in practise it runs in the oil mist. When you take this black residue out it feels like a graphite deposit. No matter what oil companies say, and I am the first to admit chemistry was never my strong suit, whatever it is smears the clutch plates and makes them slip.
As for only revving 7k, you can rev it to more than that for all I care. My friend Franzi revs his 750 Commando racer to 8.5 in the heat of battle. I try to stick to 7 max on road and 7.5 max on race engines, the more so as there is a decrease in power beyond 7 on the engine I run so nothing to be gained by revving it higher. Now as for the 750 shortstroke, that may be a different question.

ZFD said:

If you take a clutch apart that has been run on any common multigrade you find a black deposit in the grooves of the clutch friction plates

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I found the same black deposits with ATF?

ZFD said:

When you take this black residue out it feels like a graphite deposit.

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Feels like graphite? Not a very scientific analysis (I would say it felt like minute particles of worn clutch plate)

Apparently clutch plates can contain graphite!

http://www.megagraphite.com/graphite
Graphite:

It is inert to almost all substances including corrosive chemicals even at elevated temperatures making it ideal for gaskets, packing material, brake and clutch plates, etc.

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ZFD said:

No matter what oil companies say, and I am the first to admit chemistry was never my strong suit, whatever it is smears the clutch plates and makes them slip.

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Or in other words - you don't really know what it is.

LAB, not sure what you are saying that a Commando clutch is not a dry clutch.

Sure seems like it to me. The primary lube is for the chain, and IF some gets, unfortunately into the plates, then yes there are slots for it to try to come out of.

But those slots are a solution to a problem that results from, and only from, running a chain in there.

By belt primary needs to oil and so my clutch is always wonderfully dry. No need for slots because nothing gets in there.

1up3down said:

LAB, not sure what you are saying that a Commando clutch is not a dry clutch.

Sure seems like it to me. The primary lube is for the chain, and IF some gets, unfortunately into the plates, then yes there are slots for it to try to come out of.

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It might be a dry clutch-but it runs in oil so how can it be truly dry?

Have you ever stripped a Commando clutch? If you had, then you would know the plates would be completely soaked with oil.

LAB asks: " have you ever stripped a Commando clutch? "

Well, yes Les, I have. I have owned seven Commandos since 1969, so yeah, I have, many times.
However, at no time have my clutch plates been "completely soaked with oil", as yours apparently are.
Yes, they need cleaning once a season, some sludgy grime gets in there, but they are far from "soaked with oil"

Les, because your plates are so soaked with oil, perhaps you are overfilling your primary?
I have always kept the lube a bit below the level of the drain plug, just enough to get some on the chain.
I mean this advice with respect because I am well aware of your very strong Commando knowledge!

1up3down said:

LAB asks: " have you ever stripped a Commando clutch? "

Well, yes Les, I have. I have owned seven Commandos since 1969, so yeah, I have, many times.
However, at no time have my clutch plates been "completely soaked with oil", as yours apparently are.
Yes, they need cleaning once a season, some sludgy grime gets in there, but they are far from "soaked with oil"

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Sorry, you really seem to be missing my point that the standard Commando clutch doesn't operate in a totally oil-free environment as it has to function basically contaminated with oil-so it can't be considered a truly dry clutch.

1up3down said:

Les, because your plates are so soaked with oil, perhaps you are overfilling your primary?
I have always kept the lube a bit below the level of the drain plug, just enough to get some on the chain.

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Yes, but the Mk3 primary chain also has to pick up sufficient oil to keep the auto tensioner "hopper" charged with oil-so running a Mk3 with less than the required amount of primary oil may not be such a good idea in my opinion.

I've owned a MKIII since the mid 90's. I bought as a basket case to SPECIFICALLY try and discover it's secrets of E-starting functionality. I assembled the entire drive train from parts in boxes. I now own 3. One with 7 miles, never been registered.
Since 2004 I've been very intimately involved with the starter aspect with the release for sale of my replacement starter. Having now sold well over 500 starters, I've now been a focal point of MKIII starter failures and issues.
While not a VERY common issue the sprags can snag and spin up the starter to 45,000 RPM if the overload clutch does not jump/index under the load. A blown up armature is the result.... The starter will not explode it's own armature if run wide open with no load.

Just a few days ago I received an exploded starter where the owner DID not even E-start the engine... then while out on a ride the sprag caught and all kinds of noise and final destruction ensued. It had just been "upgraded" with the new style sprag with more dogbones/rockers. It ran sucessfully as an estart for several months prior to upgrade.

Dry clutch....is a joke.I recommend the primary run with engine oil 50W is my first choice then 20-50 summer then 40 winter or 10-40. NEVER ATF in a MKIII. Keep the fluid level low but enough to keep the dampers functional. A bronze oil soiled clutch WILL slip even with the gearbox oil being kept out (clutch rod seal in place) though it took 5 seasons (almost 10k miles) to finally start slipping. Since MKIII are not typically race bikes you will find the clutch slips (21T sprocket 4th gear) at a much lower RPM, closer to where the peak torque is. Mine will not slip in 3rd.
My MKIII clutch research stopped at that point, pursuing starter research instead.

And Mk3 have a sprag which I would expect won't last long without oil, plus backlash gears, etc. etc.
it was recomended to me to use ATF in the primary of my Mk3 and it was noisey. I changed to 20w 50 and the noise disapeared and it seemed to be smoother and operate better.
I used Barnett friction plates and standard lapped steel plates. No slip or drag, but the engine is standard, so there's no big torque or revs involved.
The clutch is always wet.
graeme

nd how to fix once and for all thanks Norton Dave .

Sorry new to this sight my message was half sent . To all thanks for your input . I pulled down the primary and found the sprag blown up .It appears to be the old problem boya ignition and when you require power to start it drains the amps and the bike will backfire . I think that a new type of electronic ignition with a lower runing amp draw is the only answer . Any one know a cheap source for sprag . About the primary oil , yes it is a dry clutch , but the tensioner and associated gears need lube too , never had any problems with 20 w 50 engine oil , I would stay away from ATF , amongst other things it is hydrascopic and retains moisture.