Henshaw's "Essential Buyer's Guide" alleges (page 36) that some machines have dipsticks that are "too short" and hence deceive one into overfilling the oil tank.
Yet a discussion on this list (http://www.nortonownersclub.org/noc-chat/technical4-commando-forum/616885218) â on Norvil one-way breather valves â has a picture comparing short and long dipsticks (http://www.nortonownersclub.org/noc-chat/technical4-commando-forum/616885218/804747369/img_0263_2-jpg) that clearly shows the H and L marks on the short stick to be lower than those on the long one.
The dipstick illustrated on the Andover Norton spares pages is clearly the short variety, and appears to have the marks in the same position as the short one illustrated in the one-way valve thread.
My current Commando has a short dipstick, and has oil soaking the air filter up to the level where the oil tank breather enters the backplate of the filter chamber.
The Commando I had 30 years ago had, if memory serves, a long dipstick, and never blew oil into the air filter.
(The old Commando was a pre-1972 model with timed breather; the current one is a 1972 which has both the notorious back-of-crankcase breather and an 850-type back-of-timing-chest one.)
Can anyone shed light on all this?
Rather conveniently it tur…
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Previously Chris Grimmett…
Previously Chris Grimmett wrote:
...
The bike in question is a 1974 Mk.lla 850. Could we have comparative measurements from some other bikes?
{JW} I'll check and photo mine -- but not before the weekend
[Julian - I don't think the links above are working]
{JW} Thanks for heads-up; the URLs are indeed inoperative, although the "Norvil one-way valve" hyperlink in fact takes one to the thread in question -- odd, especially since I unsuccessfully attempted to edit it to be normal text ..
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It's not something to do…
It's not something to do with the different oil tank as fitted to the early Fastbacks is it?
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I've got two 850 Commando…
I've got two 850 Commandos , one with a short (Mk 1A) and other with a long (Mk 3) dipstick. Never fill either to the Hmark anymore, maintaining oil level between L mark and midway only. Seems to work fine with no seeps. Recall with both of them that they would spray oil around and get smokey if filled to the H mark.
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I just bought a new dipsti…
I just bought a new dipstick/cap from RGM because I could not get the original to seal properly. My bike is a '75 MK3 and the markings are as follows relative to the inside of the cap (seal surface):
Original dipstick: H at 74mm, L at 90mm down
New dipstick: H at 68mm, L at 88mm
Martin
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72 750 and 74 850 MK2A. bo…
72 750 and 74 850 MK2A. both H 63mm L 79mm, both original fitment as far as I can make out. I now only ever fill to the L mark, filling to the high gets oil on the air filter.
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The early Fastback with th…
The early Fastback with the oil tank incorporated into the side panel doesn't have a dipstick. There is a clear sight tube at the front inner edge of the tank. It doesn't stay clear for very long and is another prime source of oil mist. My home made dipstick lives in a piece of plastic tube which feeds into the swinging arm end cap so once the level has been seen, the dipstick drains into the swinging arm bearing. Ok it's not EP140 but it's oil and I know it's getting to the SA bearing cos it pisses out the crappy o ring oil seals
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Why not, after draining th…
Why not, after draining the oil tank, put in the quantity as shown in the owners manual?
Then put in the bayonet cap and see where the oil level is indicated and then mark the full position with a file or Dremel? The next time you re-fill just fill it to the previously made full mark.
Mike
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Many thanks for all these…
Many thanks for all these comments; I can add two new ones
1) a contributor to the Access Norton site tested the capacity of his tank and posted a picture of the level corresponding to different quantities of oil http://www.accessnorton.com/oil-tank-capacity-t20007.html
2) it's occurred to me that according to Vane's "Complete Story", 1970 Roadster and S models had a central oil tank with battery located behind (see picture on page 92).
Since this tank is approximately cuboid, whereas all other tanks are trapeziums in side view, it follows that (a) there's the possibility of a different filler-cap to H distance, and (b) the H to L distance must be different.
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I've finally had a chance…
I've finally had a chance to photograph my dipstick (no, no, ... the one illustrated here ... )
As can be seen, measured from the underside of the rivet, we have * 91 mm to end of dipstick (or 3.5 in., as in Henshaw) * about 78 mm to "L" (approx. 3.125 in.) * 61 mm approx. to "H" (approx. 2.325 in.)(so about 17 mm [0.8 in.] difference between high and low)Henshaw suggests no more than 0.25 in. above "L" on "short" dipstick, i.e. to approx. 72 mm [2.875 in.]
Attachments dipstick2small-jpg- Log in to post comments
Previously michael_sulliva…
Previously michael_sullivan wrote:
Why not, after draining the oil tank, put in the quantity as shown in the owners manual?
Then put in the bayonet cap and see where the oil level is indicated and then mark the full position with a file or Dremel? The next time you re-fill just fill it to the previously made full mark.
Mike
That's what I would do!
Dan
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Previously michael_sulliva…
Previously michael_sullivan wrote:
Why not, after draining the oil tank, put in the quantity as shown in the owners manual?
Then put in the bayonet cap and see where the oil level is indicated and then mark the full position with a file or Dremel? The next time you re-fill just fill it to the previously made full mark.
Mike
Mike, On my 1970 Roadster I did just that. The manual says 5 pints but with a totally cleaned out and empty tank after just adding about 4 pints out of a 5L container, the oil was up to the filler neck!!
Just done another oilchange and used a quart B.P. oil bottle and exactly 2 quarts (4 pints) totally fills the oil tank.
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Ian: I no longer have a Co…
Ian: I no longer have a Commando so I cannot comment on the quantities of oil required to bring the tank up to the mark so to speak. I was just thinking that the owner's manual for a specific year and model would state the correct quantities required.
The service manual I have for the 1959-1967 Models 50, ES2, 88,99,650, and 750Atlas says that the oil tank "working capacity" is 4.5 pints. I would not think that the working capacity of any model Commando would be any less. Is there any possibility that your oil tank is a replacement of dubious ancestry?
Mike
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Previously ian_richtsteig…
Previously ian_richtsteig wrote:
Previously michael_sullivan wrote:
Why not, after draining the oil tank, put in the quantity as shown in the owners manual?
Then put in the bayonet cap and see where the oil level is indicated and then mark the full position with a file or Dremel? The next time you re-fill just fill it to the previously made full mark.
Mike
Mike, On my 1970 Roadster I did just that. The manual says 5 pints but with a totally cleaned out and empty tank after just adding about 4 pints out of a 5L container, the oil was up to the filler neck!!
Just done another oilchange and used a quart B.P. oil bottle and exactly 2 quarts (4 pints) totally fills the oil tank.
Oil filter cartridge circuitand piping will hold a fair amount - stillremainingafter an oil change.
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Previously ian_richtsteig…
Previously ian_richtsteig wrote:
Previously michael_sullivan wrote:
Why not, after draining the oil tank, put in the quantity as shown in the owners manual?
Then put in the bayonet cap and see where the oil level is indicated and then mark the full position with a file or Dremel? The next time you re-fill just fill it to the previously made full mark.
Mike
Mike, On my 1970 Roadster I did just that. The manual says 5 pints but with a totally cleaned out and empty tank after just adding about 4 pints out of a 5L container, the oil was up to the filler neck!!
Just done another oilchange and used a quart B.P. oil bottle and exactly 2 quarts (4 pints) totally fills the oil tank.
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Rather conveniently it turns out, I drained the ex-Italian rally oil from the Commando yesterday and changed the oil filter. As I also cleaned out the oil tank (very little sludge this time), the tank cap/dipstick was lying on the workbench waiting to be measured. Mine shows the H at 49mm from the inside top of the cap and the L at 74mm.The bike in question is a 1974 Mk.lla 850. Could we have comparative measurements from some other bikes?I guess a key parameter for this could be to run the problem machine with successively lower oil levels until the air filter no longer gets drenched whilst checking that there is still sufficient oil to do the job, for example by checking its temperature. I had always hoped that the designers had allowed a good excess of capacity over what was actually required - or did they simply fill the available volume with an oil tank of that size? Another question for John Favill ...
[Julian - I don't think the links above are working]