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 other things you know how it is sometimes.

Anyway I went out for a ride and when I got home theres quite a lot of oil dripping from the back of the engine around the centre stand pivot/front of gearbox area. I can't see exactly where is is coming from but it is engine oil. Is this something to worry about or is it just getting rid of the excess oil through the breather?

I've been trying to check using some technical notes and came across one saying this can be caused by the oil level being too high because your dipstick is 3.5" long when it should be 5" long. (Norvil tech tip). Can anyone tell me which Commando should have the 5" dip stick. Mines a 1974 Mk2A Interstate and I've been wondering if I have been overfilling it in the year and a half since I've had it (it has a 3.5" dipstick). The bike has always leaked oil from this area despite removing and refitting the oil tank, fitting new oil lines and new clips which are all fully tightened and there are no leaks from the oil tank itself.

When you change your oil and filter, fill it with 3 quarts of your favorite, run the engine to check for leaks and fill the new filter, and let it sit 10 minutes. Check the oil level on the dipstick. This should be your new maximum oil level. You may scribe a mark if you like. On most Commandos, I find this is roughly halfway between the L and H mark. I never let it get below the L, but never higher than halfway between the two.

I have a half-dozen dipsticks in the shop and they are all "short". I have never seen the legendary 5" one.

A possible source for your leaks is the primary side crank seal. Remove the level plug and if you get oil draining, you are leaking past the crank seal. While riding this gets whipped by the primary chain and pushed out the sliding "seal" behind the clutch. This will be most noticeable after the bike has wet sumped. I like to run just enough ATF in the primary case to touch the bottom of the chain.

Ron L said:

When you change your oil and filter, fill it with 3 quarts of your favorite,

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That'll be 2.83 Litres then, in UK terms (US quart measures not used here in the UK).

My Mk III dipstick is 3-5/8" long, and I've never had any oil spill from the tank.
But only top the oil tank up after running the engine, or at least after transferring any oil in the sump back to the tank.

Had chance to have a look at where the oils coming from and it seems like its from the air intakes on the plastic box air box. Mainly dripping from the left hand side intake. The air box front plate is also dripping so it looks like the whole of the inside of the air box has had a good soaking. The primary is all ok with no extra oil in it - whats there is still all ATF.

Would this normally happen with overfilling the oil tank or is there something else causing it? The oil is now just above the max level on the dipstick.

mike916sp said:

Would this normally happen with overfilling the oil tank

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Yes that would be quite likely, if the oil tank still vents to the black air box?

As has been said already by Ron L, only fill to a maximum of about halfway between the level markings on the dipstick.

Yes LAB its all standard with the tank venting to the air box. Looks like the panic might be over then - I was starting to worry I might have kna****ed something up seriously due to a stupid oversight.

Must make sure I dont overfill again!!! Thanks.

Re:

Ron L said:

When you change your oil and filter, fill it with 3 quarts of your favorite, run the engine to check for leaks and fill the new filter, and let it sit 10 minutes. Check the oil level on the dipstick. This should be your new maximum oil level. You may scribe a mark if you like. On most Commandos, I find this is roughly halfway between the L and H mark. I never let it get below the L, but never higher than halfway between the two.
.

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I know it's an old thread, but I have the shorter 3 5/8" dipstick, just to confirm the above, the oil should sit between the L & H marks on the shorter dipstick?
Sorry if it's daft question, rather be safe than sorry.

yes between L& h