Mine is in the middle of the safe zone and no issues. Just clarifying.

 

See post # 10.
DK is knowledgeable.
Also quotes the Co.

FWIW...oil level at the 1/2 way point between hi & lo marks is my goal.

 

I hear what you're saying, and respect your experience, but the oil passages only hold so much oil, so whether the pump is drawing from a 2 quart reservoir, or a 2 gallon reservoir makes no difference.

As has been said, the cause is elsewhere. Possibly your umbrella valves, or some slight blockage in the return passages causing higher pressures in the rocker boxes. Or a combination of the two that shows up more quickly when you are running hard.

 

I love how the manufacturer gives you imprecise and vague instructions on how to check it...then warns you that if you do it wrong it will cause catastrophic damage!

 

Make sure there is some oil present in either the tank, or the dry sump area of the engine. Failure to maintain oil to precise specifications will void warranty.

 

Being a dry sump design (separate oil tank), it makes sense that it would not matter what size the tank was, nor how full the tank was....it should all be irrelevant to how much "blow-by" or, as HD calls it, Oil Carryover there is.

It make sense, and therefore there is a justifiable basis for believing that no matter how full the tank is, it will not have an affect on blow-by.

The water is further muddied by different bikes have different amounts of blow-by.

But, there are two facts-

1. HD specifically states that if you overfill the tank it can result in oil carryover (blow-by).
2. We have seen hundreds of bikes, where the level of oil in the tank has a direct affect on how much oil comes out of the breather bolts...everything else being equal.

Why it works this way...when oil level would seem to be irrelevant...I do not know.

But Harley knows it works this way, which is why they put a warning about it in the manual, and we have seen it work this way.

btw, we have also seen many bike where regardless of the level in the oil tank, they will get excessive blow-by. This is when a deeper looks should be taken at umbrella valves, oil pumps, heat, oil viscosity, etc.

Here is a LINK to a thread examining this subject in more depth.

 

I could see the oil level being an issue which would cause blow-by, but only if it were blocking the return line in the oil tank, leading to increased back pressure on the oil passages.

But, if experience says otherwise for some people, who am I to say they are wrong?

Thanks for the info.