CHECKING ENGINE OIL LEVEL (2004)

Funny there's no spring on my cap either.

There's usually an internal spring as it provides sufficient tension to prevent the cap from unscrewing past the lugs on the tank filler neck.

When fully screwed down the cap should be in contact with the inner plate, thus clamping the plate and gasket tightly to the filler neck.
 
There's usually an internal spring as it provides sufficient tension to prevent the cap from unscrewing past the lugs on the tank filler neck.

When fully screwed down the cap should be in contact with the inner plate, thus clamping the plate and gasket tightly to the filler neck.
I didn't realize that but I noticed it's not listed in parts breakdown nor do I see a spring on the replacement cap shown at AN.
 
I didn't realize that but I noticed it's not listed in parts breakdown nor do I see a spring on the replacement cap shown at AN.
Never mind, I now see it's internal and not visable.
 
My 75 and 76 use a different length of dipstick markings compared to earlier model(s) dipstick high and low marks. Correct me if wrong. Yes to just above low mark , or middle is good before a longer trip.
 
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My 75 and 76 use a different length of dipstick markings compared to earlier model(s) dipstick high and low marks. Correct me if wrong. Yes to just above low mark , or middle is good before a longer trip.

Yes, or basically keep it below the level where oil gets blown out of the breather and not filled right up to or beyond the full 'H' mark depending on whichever dipstick markings they are.
 
I think you need to look at the cap mechanism again and compare what you have with the pictures below.

The cap gasket rests on the rim of the filler neck under (when in its normal position) the plate the dipstick is attached to.

The spring is between the plate and the cap so when the cap is screwed down (demonstrated by the screwdriver blade) all that moves (or should move) is the cap as the gasket is already resting on the rim of the filler neck.
You`re right.. the gap/difference is really small indeed. Sorry for the bias.
 
You`re right.. the gap/difference is really small indeed.

It isn't the distance the plate travels inside the cap, only that once the cap plate with the gasket beneath has been dropped onto the filler neck then it can go no further even when the cap is screwed down.
 
"from JPN bikes"
Welcome aboard.
Just a note, around here, JPN means 'John Player Norton'.
Again, Welcome. A lot of knowledge on this boards.
Cheers....
 
Last edited:
"from JPN bikes"
Welcome aboard.
Just a note, around here, JPN means 'John Player Norton'.
Again, Welcome. A lot of knowledge on this boards.
Cheers....
Thank you, Michael :] I actually know about JPN Norton and I actually have one in these colors. However there is a lot of discussion about the nomenclature... whether its JPN or JPC according to some catalogue.. or its Union Jack, and JPN means the faired special only... :]
 
Thank you, Michael :] I actually know about JPN Norton and I actually have one in these colors. However there is a lot of discussion about the nomenclature... whether its JPN or JPC according to some catalogue.. or its Union Jack, and JPN means the faired special only... :]

Yes. JPN means the faired race replica only. Lots of lively debate over what the red, white and blue Roadsters are called…
 
Thank you, Michael :] I actually know about JPN Norton and I actually have one in these colors. However there is a lot of discussion about the nomenclature... whether its JPN or JPC according to some catalogue.. or its Union Jack, and JPN means the faired special only... :]

If it's a white with blue and red striped Roadster then there's no record of the factory ever referring to that as John Player, only as: "Blue Stripe", "White with Blue Stripe", "Dayglow White, blue stripes" or "White with Red and Blue Striping" finish.
Screenshot-from-2022-07-20-09-12-39.png
 
Not sure if the fact that my bike is a Mark II has anything to do with it, but I checked yesterday evening when I got home.

I filled the oil level to just under the full mark on the center stand. Then I put the bike on the side stand and checked again, the oil level was just slightly over the mark.

No real significant difference in the oil level reading. I always push my cap down tight against the gasket so I get consistent readings.
 
I have had several Commandos over the past 45 years so I KNOW not to fill the oil tank to the high mark
or the oil will blow out and oil will run down the rear of the oil tank.

However, I had a senior moment and topped up my oil tank to the H level mark. Lo and behold the oil blew
out of the tank and ran down the rear of the oil tank ! (don't tell me I KNOW)

As stated above the dip stick is attached to a spring loaded disc held within the chrome cap so it does
not matter much if the chrome cap is screwed shut or not the spring loaded plate rests on the oil tank rim.

My dipstick is 90mm long (insert jokes here !) from the rivet into the spring loaded shaped disc held in
the cap
The H level mark is 60mm from the rivet
The L level mark is 76mm from the rivet

As a scientific experiment (I used to be a technical bod) I removed the excess oil from the H level mark
to the L level mark using a surgical syringe with a piece of tube attached and put the oil removed into a
laboratory measuring cylinder. I did all my experiment with the bike on the main stand.

I removed 350ml to lower the oil level from the H level mark to the L level mark
And 195ml to lower the oil level to where I like it to be for shorter journeys - about half way between
the H and L level marks.

Sorry to have to use nasty SI units, but I was a scientist and there is a bit of a discrepancy between
UK Imperial and American volumetric units. IIRC the UK gallon is bigger than the US gallon !

The official Commando manual states that the oil tank capacity is 5 Imperial pints or 6 US pints or 2.8L.

(So UK Imperial pints are bigger as well ! What do you guys do in the US with your pints of beer ?
Although since we joined the EU UK beer bottles are only 500ml. Back to proper pints methinks !)

I'm not sure if that is just the oil tank (as stated) or would include filling all the oil pipes and the oil filter
to give a volume of oil that meets the H level mark.

BUT to remove 195ml from 2800 ml to leave 2605ml of oil and give a level about half way between
the H and L level mark does not seem to be much of a worry to me.

And finally I KNOW NOT TO FILL TO THE H LEVEL OR OIL BLOWS OUT you don't need to tell me
I've been putting oil in Commandos for 45 years.... or perhaps you do ....... as I did it !
 
There's also a small amount of oil left in the sump (pre-sumping). So, reading in the oil tank would be slightly lower after you run the motor for the 1st time after an oil change, having emptied the sump as part of the oil change. Maybe also for the supply up to any external oil filter, even with a pre filled replacement filter. Just being pedantic, but after an oil change, I run the bike for a minute or so, then do my final check/top up. It takes another glug, or so from the can. :)
 
That‘s exactly what I did. Changed oil and filter went for a blast then
stupidly topped up to the H level. When I know to top it up to half
way between H and L as I have been doing for 45 years !
 
I have had several Commandos over the past 45 years so I KNOW not to fill the oil tank to the high mark
or the oil will blow out and oil will run down the rear of the oil tank.

However, I had a senior moment and topped up my oil tank to the H level mark. Lo and behold the oil blew
out of the tank and ran down the rear of the oil tank ! (don't tell me I KNOW)

As stated above the dip stick is attached to a spring loaded disc held within the chrome cap so it does
not matter much if the chrome cap is screwed shut or not the spring loaded plate rests on the oil tank rim.

My dipstick is 90mm long (insert jokes here !) from the rivet into the spring loaded shaped disc held in
the cap
The H level mark is 60mm from the rivet
The L level mark is 76mm from the rivet

As a scientific experiment (I used to be a technical bod) I removed the excess oil from the H level mark
to the L level mark using a surgical syringe with a piece of tube attached and put the oil removed into a
laboratory measuring cylinder. I did all my experiment with the bike on the main stand.

I removed 350ml to lower the oil level from the H level mark to the L level mark
And 195ml to lower the oil level to where I like it to be for shorter journeys - about half way between
the H and L level marks.

Sorry to have to use nasty SI units, but I was a scientist and there is a bit of a discrepancy between
UK Imperial and American volumetric units. IIRC the UK gallon is bigger than the US gallon !

The official Commando manual states that the oil tank capacity is 5 Imperial pints or 6 US pints or 2.8L.

(So UK Imperial pints are bigger as well ! What do you guys do in the US with your pints of beer ?
Although since we joined the EU UK beer bottles are only 500ml. Back to proper pints methinks !)

I'm not sure if that is just the oil tank (as stated) or would include filling all the oil pipes and the oil filter
to give a volume of oil that meets the H level mark.

BUT to remove 195ml from 2800 ml to leave 2605ml of oil and give a level about half way between
the H and L level mark does not seem to be much of a worry to me.

And finally I KNOW NOT TO FILL TO THE H LEVEL OR OIL BLOWS OUT you don't need to tell me
I've been putting oil in Commandos for 45 years.... or perhaps you do ....... as I did it !
I have just changed the oil last week on my Mk3, bike was not leaving any drops of oil on the floor and the back weel was clean of oil too before the oil change, after the oil and filter change the back weel rim was with oil mist and drops of oil on the floor.

The bike has done 250 km since.

I have reduced the oil level by 300 cc, is close to the L marc now, clean the back weel rim and bike bottom motor parts carefully, shiny bike again!

I will report after I do 250 km hopefully today or tomorrow!
 
I have just changed the oil last week on my Mk3, bike was not leaving any drops of oil on the floor and the back weel was clean of oil too before the oil change, after the oil and filter change the back weel rim was with oil mist and drops of oil on the floor.

The bike has done 250 km since.

I have reduced the oil level by 300 cc, is close to the L marc now, clean the back weel rim and bike bottom motor parts carefully, shiny bike again!

I will report after I do 250 km hopefully today or tomorrow!
I have done the promised 250 km, no drop on the floor although a drop was hanging from the cradle, a little oil must in the back rim probabli for the chain.

I would say that a reduction of oil mist is significant and comfirm that the oil level is very important.

I cleaned everything again and took 100 cc more, so I'm at the L marc now, ready to test again with the same conditions when possible.

Let's see if i can get a 100% clean bike!
 
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If it's a white with blue and red striped Roadster then there's no record of the factory ever referring to that as John Player, only as: "Blue Stripe" "White with Blue Stripe", "Dayglow White, blue stripes" or "White with Red and Blue Striping" finish.
View attachment 98116
What a lovely picture! Where can I get one?
 
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