Hitchcocks Forum

Reading on an earlier post, it is mentioned that the oil filler cap on earlier engines has 2 positions, the tight being for transporting. I am sorry but I can't accept this but also can not offer an alternative reason for the 2 positions. Why would it need a transport position, unless the bike is lying flat on its side it is highly unlikely oil would leak out. I would suggest when the engine is running, oil is more likely to be splashed around the height of the cap and surely this is when the tight position would be most needed.

Does anyone know a factual answer?
Happy new year, Sam

Hi Sam, most old British bikes are fitted with two position oil caps and two position petrol caps. I always understood that the second/loose position was to prevent the cap being lost when not fully tightened, logic states you would not have a riding and a transport position on the petrol cap, I guess someone started this story and the gullible ones fell for it.

No personal experience myself but I gather from Gordon May's book Overland to India he had used the 'tight' position incorrectly and the crankcase pressure resulted in oil spouting from every orifice! It sounds like the alternative position allows the crankcases to relieve pressure.

As Milsy says. I find that my 2000 Bullet uses less oil if the cap is on the first position, there is now no more pressure from the duckbill breather throwing oil over the rear wheel. It seems to releive the crankcase pressure which the tiny pinhole breather in the cap can`t handle.

There is a breather hole in the top of the crankcase into the top of the oil tank and on the later Indian ones they used this hole with a breather of the top of the oil tank, but removed the underbarrel breather due to emission reregulations, earlier ones just had this pulsing effect in the oil tank and this, ah never mind nobody cares anyway, it's new year

I had a Sixty-Five for a bit a few years ago which had this system.
All I can say is that in the fully tight position I got oil leaks and excess oil from the crankcase breather. In the loose position the problems disappeared.
The later models have a "sealed" oil filer cap but rely on the catch can system for engine breathing.

I always tighten my oil filler cap onto the second position but I also check the pinhole vent in the cap regularly to make sure that it is venting. Never had any pressure build up problems on any of my 7 old British Enfields.

It looks like we have some information on here with peoples personal experience re oil leaking with the cap on tight, (which I would consider the correct position).

As most of you may know I have never owned an Indian Bullet so I would be interested to hear from people who have, for instance does anyone have a user /riders handbook which states that the cap should be loose, my exprience is the reverse of this including my 1959 Super Meteor which always has the cap down on the second position and which has not leaked or blown out any oil in the past six years of ownership, except on one occasion when the oil return blocked and the crankcase filled with oil.

Dennis: This seems to only apply to the Bullet singles with a duck-billed breather. There is no reference to the dip stick closing procedure other than `locate, depress and turn clockwise`, in the Handbook. So I would say again, that the twins are not prone to pressure build-up in the crankcase like the Bullet singles with a duck-billed breather.

I am with Dennis C 100 percent on this one. My Enfields, including 350 and 500 Indian machines, 500 Redditch '55 model and the two racers ALL have their dipsticks / filler caps screwed down TIGHT after I fill or check the oil in them. The 'transport position' is just a myth - the stop that the caps come to if you loosen them off is just to stop them vibrating all the way off, as with the petrol tank caps and countless other oil tank caps on many other British bikes. If an engine happens to blow less crap out of the breather because the cap is backed off and all is well as a result, then that is a bonus side effect, but not a design feature. Also, not all Redditch caps I have seen have a vent hole in them, so it must be important to have the right type of cap for a given engine / breather type.