hi. i have a 2002 harley fatboy with the frankensten kit on it. When i check the oil it is always at the k in check which is about 1/4 of an inch above the add oil mark. I used to fill it up to about 1/2 full on the dip stick but it always goes down to the k in check. My comprewssion is 153 psi on both cylinders and it does not show any smoke coming out of the exaust. my spark plugs are fine front and back have a little brown on them and it does not heat up. My question is, is theis ok to leave it at the k or what?

 

What happens if you leave it at the 1/4" above the "add" mark on the stick?

Does it stop at the 1/4" mark, or does it go lower still?

If it stops at the 1/4" mark, then in the future I would fill it to the 1/4" mark and see if it stays there until the next service?

If it doesn't stop at the 1/4" mark, IMHO, I wouldn't add oil until it gets to the add mark..... Then I would try filling it to the 3/4 full mark (or 1/2 full mark) and see how many miles you can run until you need to add oil again. You could then figure out how many miles you get per quart of oil used, and see if your oil usage is acceptable.

 

it will stay at the 1/4 inch from the add oil mark till the time i have to change the oil (5000 miles)

 

As long as you don't put too much in so it doesn't over flow the tank, your fine on a Softail.

Now as Softails get old, they tend to empty oil into the engine by the old o-ring in the oil pump.

So check it properly so you don't let the old girl get ahead of you.

Drive it till it's warmed up and check the oil immediately after cutting it off. It's save then to top it off at full mark.

Mine drains the oil tank setting 6 months . If someone didn't understand a Softail, and the added oil, it would be coming out the dip stick hole shortly.

Interestingly, when mine is empty, it take a good 10 minutes driving around 2000 rpm or so for it to refill the tank. It's only replacing slightly more than it's putting out to lubricate.

If you keep it properly full, it will probably be good for the life of that oil between changes.

I alway did the 2004 Duece I have like that. I never have had to add oil after an oil change and it has 50k on it.

Now I also rode reasonably rarely over 3000 rpm.

Your bike is not using oil because your putting too much in the tank. If you put too much in, it will tell you by coming out the dip stick fill hole.

 

So is it OK to leave it in the OK zone? I would think so..

 

I'm no mechanic nor the voice of experience here
But I'll say "I" would be fine with that and not worry a bit

KTF

 

Then IMHO, I would fill it to that spot after each oil change, and I wouldn't add oil unless/until it hits the add line or just below....

It IS OK to run the bike with the oil level between ADD and FULL.....

 

Sorry Jackie, I don't mean to nit pik, but I will respectfully disagree with the portion I have highlighted above...

For those reading who don't understand, the Twin Cam oil system, it is a dry sump system. The oil is pumped through the engine, then "scavenged" (removed by way of pumping) from the engine cases, and sent back to the oil tank. There is rarely over 6-8 ounces of oil in the crank cases at any given time. It is all mostly in the oil tank.

The oil pumps have two halves, or sides, with different jobs. The pressure side has two gerotors that take oil from the oil pan, and pump the oil through the cam plate & engine. The scavenging side has two gerotors that suck the oil from the engine cases, and pump it back into the oil pan.

In the case of Twin Cam Softails, the oil Pan is located under the seat, above the cam chest. Unlike the EVOs and Shovelheads before the Twin Cam, there is no check valve to stop the oil in the oil pan, from free flowing into the engine cases. It is the fit of the gerotors, when they are not spinning, that stops the oil from free flowing into the sump when the engine is turned off. The older/higher mileage the Twin Cam softail, the more likely, and more quickly, the oil will seep past the gerotors in the oil pump and settle in the engine cases.

This is usually called "dry" sumping. Meaning the engine sumps when it's not running. This is not a debilitating issue. The bike can be started, and the pump (unless totally worn out, or damaged) will put the oil back into the oil tank in pretty short order, and the system will function as designed.


Having said that, the Twin Cam oil pumps have some important O-rings on them. They are o-ring #9 in the parts pic below, part #11286, #10 in the parts pic below, part #11293, and two #12 in the parts pic below, part #11301.

The o-ring labelled #9 below, fits between the oil pump body and the cam plate. If that o-ring is damaged, the pump would lose a lot of its oil pressure, and oil would bleed under pressure right into the cam chest. This would cause a wet sumping issue, that I suspect would show itself fairly rapidly.

The oil pump is supplied by an oil line from the raised oil pan, to the side of the engine case at the cam chest, and passes through the cam plate, to the pressure side of the oil pump. The interface where the oil passes through the engine case to the cam plate, is where the #12 o-rings come into play. Obviously if there was a leak at that o-ring, it would surely allow the oil pan to drain into the engine sump, but the oil pump would also suck air as it tried to pump oil. I believe that would cause the oil pump to lose prime and the engine would lose oil pressure. Again, an issue that would manifest itself fairly rapidly.

The o-ring labelled #10, is fitted to the "snorkel" on the oil pump body that fits into a machined spot, connecting the cam chest to the crank side engine case. That o-ring seals the "snorkel" so it can suck the oil that accumulates in the crank side engine case and pump it back to the oil pan. If that o-ring fails, it will cause the engine to wet sump in short order, and you will know it very soon. There are numerous stories of people pinching that o-ring while reinstalling the oil pump after a cam change. They find out quickly and have to redo their work before they can go for a ride.

While a few of those o-rings could cause oil to build up in the cam chest, they will also cause much more serious issues that would keep the bike from running well enough to go for a ride... Additionally, if one of those o-rings fails, it is highly unlikely the engine could recover from a sump full of oil and run well, like what happens when oil seeps past the oil pump gerotors and people can still start, ride the bike, and have no issues.

If I am wrong about this, I welcome the correction...





I hope someone reading this thread finds this info helpful...

 

Caution.. not finished. Updating with some attachments..

WOW. My statement about the o-ring in the oil pump was something I heard on here.

After 2012 , mine leaked down about a quarter inch in 3 months while we lived in Mexico or Florida.

When I parked it in 2020, I replace the fuel, and drive in about 30 minutes couple times a year when we are back in VA. It empties the tank then. Obviously going out the line to the pressure side of pump that goes then to filter and thru engine.

In 6 months, it's doing what you just said or going by pressure side of the oil pump rotor (pump has 50 k) thru the filter and into the crankcase.

And interesting thing about the TCb design is for the first few years, it maintains couple inches of oil in the crank case and timing chain galley. It's probably about 16 ounces or so. Over a 1/4 inch on stick. It's not truely 100% dry sump.

There's a lip in the bottom of the sump that traps it and keeps it from the oil pump scavage side from getting it.

The early design of the TCb allowed oil splash off crank to lubricate inner cam needle bearings.


When I start and ride the bike, I keep the rpm around 2000 due to all the oil in engine. You really can't tell there is an issue. It does take a good while to get normal.

Maybe if my son finds the time to get it, we will see an issue crop up. But it does fill the tank back up now at 30mph or so.