Oil tank cap - two different types at hand, which is correct?

Jdub · Jul 12, 2023

I have two different oil tank caps based on the location of the upper and lower limits of the oil measurement. One of these is either an aftermarket imposter or possibly a legitimate cap but for a different model? The picture below shows the two, matched at the same point, and the H and L locations. Does anyone have any information on this so that I prep and use the correct cap? Thank you in advance!

ashman · Jul 12, 2023

Well it's a long standing only fill your oil level in between the high and low level on a stock oil tank so the oil don't blow out the breather so maybe the levels have changed on the second one just to get it to the right level for not overfilling the oil tank.
Just my thinking as I am not running a Commando oil tank or have a dip stick on my cap, with my 3 ltr round alloy oil tank I run 2 ltr of oil and 1 ltr air space and works for me I never do any top ups inbetween oil changes.

Ashley

MikeG · Jul 12, 2023

The one with the good gasket that doesn't leal is the correct one.

Shelby-Right · Jul 12, 2023

Hi just measured mine , 1973 looks original here's a pic ruler is under the rivet , cheers

Oil tank cap - two different types at hand, which is correct?

Tornado · Jul 12, 2023

Doesn't look like you could go wrong with either of those two level sticks....difference may be between the cross/sideways tanks vs fore/aft tanks. As long as level stays above the mesh screen at bottom and doesn't burp out the breather at all standard operating angles of the bike, you're OK.

johnm · Jul 12, 2023

Small sidetrack.

Three years ago I gave my 74 Roadster Mk11 a big birthday present. This includeed some cleaning of oil tank and repair of paint etc.

And during that time the original filler cap vanished !!!! Never been seen again over the subsequent years. Clearly taken by Martians.

I bought a new Andover one but in my head my original had oil capacity script engraved on the lid. The replacement does not.

So is my memory right or wrong? Did they have writing on the cap? Or am I confusing it with my old Matchless gone for many years?

I'm going to be 70 end of this year.

. There may be more questions of this nature to come.

NORTSTER1974 · Jul 12, 2023

johnm said:
Small sidetrack.

Three years ago I gave my 74 Roadster Mk11 a big birthday present. This includeed some cleaning of oil tank and repair of paint etc.

And during that time the original filler cap vanished !!!! Never been seen again over the subsequent years. Clearly taken by Martians.

I bought a new Andover one but in my head my original had oil capacity script engraved on the lid. The replacement does not.

So is my memory right or wrong? Did they have writing on the cap? Or am I confusing it with my old Matchless gone for many years?

I'm going to be 70 end of this year. . There may be more questions of this nature to come.

Johnny, I think you are talking about the master cylinder cap, they did have some type of mubo jumbo on there. I've never seen anything on an oil filler cap but that's just me.

Jdub · Jul 12, 2023

Thanks to all, I will try both and see which one is faster.

johnm · Jul 12, 2023

Your right there is writing on the front brake master cylinder cap.

But no I'm definitely thinking of the oil filler.

Just wondering. Nothing to be done about it anyway I guess.

possm · Jul 12, 2023

Just checked my Mk3 High 6mm low 7.5

Shelby-Right · Jul 12, 2023

johnm said:
Your right there is writing on the front brake master cylinder cap.

But no I'm definitely thinking of the oil filler.

Just wondering. Nothing to be done about it anyway I guess.

The oil cap on my 49 matchless g80 has that old nickel look and it has writhing around the top , I didn't look at the top of the Commando one , mine has a old 72 decal on top .

marshg246 · Jul 12, 2023

Jdub said:
I have two different oil tank caps based on the location of the upper and lower limits of the oil measurement. One of these is either an aftermarket imposter or possibly a legitimate cap but for a different model? The picture below shows the two, matched at the same point, and the H and L locations. Does anyone have any information on this so that I prep and use the correct cap? Thank you in advance!

See: https://andover-norton.co.uk/files/0c4/WEBSHOP VERSION Norton Commando Oil tank dipsticks AN.pdf

johnm · Jul 13, 2023

Shelby-Right said:
The oil cap on my 49 matchless g80 has that old nickel look and it has writhing around the top , I didn't look at the top of the Commando one , mine has a old 72 decal on top .View attachment 108144

Excellent !

L.A.B. · Jul 13, 2023

Overfilling oil tank and oil tank dipstick length

A simple question. Filled the oil tank in my Mk2A today a little to high by mistake. I think it had wet sumped a bit while it had been standing for a week. I know I should have run the engine for a while before checking the level and topping it up but for some reason forgot. Got my mind on...

www.accessnorton.com

Size does matter, Oil dip stick 5"???

I remember that my 73, 850's oil tank dip stick is supposedly to short at 3 3/4" (USA inch) but I didn't find out what it should be. I seem to remember someone saying 5 (US) inches or 12.7 centimeters. Is this correct?? Thank you my learned Nortonites.

www.accessnorton.com

Tornado · Jul 13, 2023

johnm said:
Your right there is writing on the front brake master cylinder cap.

But no I'm definitely thinking of the oil filler.

Just wondering. Nothing to be done about it anyway I guess.

Perhaps the engraving was some form of sacred Martian holy words, making their thievery justified?

johnm · Jul 13, 2023

That's possibly the best explanation.

That and the 70 years thing.

Oil tank cap - two different types at hand, which is correct?

Jdub

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Overfilling oil tank and oil tank dipstick length

Size does matter, Oil dip stick 5"???

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