Feuling Vented Dipstick for M8
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I had a feuling oil tank vent on my 04 FLHTI for a while on the recommendation of one of their techs. I had oil coming out of the pushrod tubes after installing their camchest kit. I ended up rebuilding the top end and all was well but at higher speeds for extended time I'd get a lot oil out of the vent tube. I removed the vent and have had no issues since. I don't think a vent right where oil, now under higher pressure from a higher pressure pump, flows into the tank is a great design.
Why do you think you need to vent your oil tank? May be very good reasons to do so...IDK...
Why do you think you need to vent your oil tank? May be very good reasons to do so...IDK...
When i upgraded my M8, i removed the crank beather hoses from the intake tract, Y-ed them together, and routed down under the bike. Never had a problem. Lot of whining about "oil under the tire" and other crap. There "might" be a drop come out, but have never seen much, just a little oil on the end of the hose. Running Feuling HP camplate and matching oil pump.
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Venting the oil tank in a dry sump system like the one used on harleys is not a bad idea. The only reason why it is not vented from the factory is the EPA. The deal is, the oil pump in a harley pumps both oil and air back the the oil tank. The vent line between the tank and the engine case allows the excess air in the tank to flow back into the engine and be expelled out the head vents.
Here is a little ******* experiment to prove my point. Pinch of the vent line between the engine case and oil tank and then rev the engine to a high idle. The oil cap will pop off because the pressure is not being relieved.
If the EPA were not involved, the oil tank and engine would have separate venting systems. The head vents in a harley engine would handle much less air/oil mist if the oil tank vent was isolated from the engine.
Anyways, a supplemental vent via a 'T' inserted into the oil tank-case vent line cannot hurt anything and might reduce the amount of oil vapor passing out the head vents.
Paul Morris and myself run this system on our big block twin cam FXRs. I run the lines from each head and the oil tank vent into a vented catch can and pay very close attention to what s captured in the tank. It usually collects about half a cup of water and a few drops of oil. On my bike, the vent line between the TC engine case and the oil spout is removed. The port on the engine case is plugged and the port on the oil spout is fitted with a hose that runs under the back bone and down the front down tube to the catch can.
Here is a little ******* experiment to prove my point. Pinch of the vent line between the engine case and oil tank and then rev the engine to a high idle. The oil cap will pop off because the pressure is not being relieved.
If the EPA were not involved, the oil tank and engine would have separate venting systems. The head vents in a harley engine would handle much less air/oil mist if the oil tank vent was isolated from the engine.
Anyways, a supplemental vent via a 'T' inserted into the oil tank-case vent line cannot hurt anything and might reduce the amount of oil vapor passing out the head vents.
Paul Morris and myself run this system on our big block twin cam FXRs. I run the lines from each head and the oil tank vent into a vented catch can and pay very close attention to what s captured in the tank. It usually collects about half a cup of water and a few drops of oil. On my bike, the vent line between the TC engine case and the oil spout is removed. The port on the engine case is plugged and the port on the oil spout is fitted with a hose that runs under the back bone and down the front down tube to the catch can.
I run both the vented dipstick and vented heads. I did it for the long term; keeping carbon to a minimum in my cylinders and prevent sumping during hard riding. Day to day can't say I've seen any real difference.
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Nope. It might solve the same issue, but it is venting a different area of the power train. The oem breather vents the head/rocker box area. The cam chest vents to the heads through the push rod tubes, and the crank case vents to the cam chest through a vent passage which is sized to insure that it also vents through the bearings, so as to lube them. The MoCo changed this with one of the oil pump upgrades, to make the pump suck through the crank bearing, to reduce the amount of oil left in the crankcase. The oil pan vents to the cam chest through a bulkhead passage.
The design of the internal breathers allows vapour to vent out of the head area, but it does not allow it to return. So the motor pushes pressure out as the pistons go down, then draws a vacuum as the pistons go up. The breather unit also contains an oil separator, and that is where the issue is. On Twin cams you can open the drain holes up and correct the issue on an other wise sound engine. Not sure if that is the case on the M8, it uses a different breather asm.
By venting the oil pan you will indirectly lesson the pressure inside of the motor. But some of the bearings are oiled because of the pressure in the motor and the way it is relieved through the motor. And venting the pan may change some of that. Redirecting the breather vent at the air box does not alter the pressures inside of the engine, it just directs what come out away from the intake.
Past that, redirecting at the the breather costs < $10. How much does that oil cap thing cost? And how much effort does it add to checking the oil level?
Done properly, you have to look real close to see that a scooter has a breather bypass done to it. There is no hiding that oil cap plumbing.
This scooter has redirected breathers, can you find the hoses?
Thank you for all the info! Yeah, I’m not about to spend that sort of money on the vented dipstick. Thought of piecing together some tubing, fittings, and either small filter or catch can is up my alley. Can’t see it hurting anything. Geared more towards a catch can or venting a filter high enough to not pull any debris or water from the road. Seems most people mount a small filter under the frame. Should that be a concern? I cannot see any tubing on that picture.
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The breather valves are one way. It can not draw anything back into the breather hoses.
And you are talking about ocasional drops of oil, not oz's, so the catch can is not needed. Just terminate the hose down beside the right rear corner of the frame.
And most people don't mount filters on them. That was an idea left over from old bottom breathers back in the day. Mid 80's and back. Those scooters did suck in on the breather tube, but Harley saw no need for a filter on them, they just ran the hose down below the from rail and it worked fine. Snd even then the filters had issues. They were dirt magnets, and they made funny noises as they began to plug up.
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23,122 Posts
What you do at the breather depends on how the back plate is set up. Past that, yes just run the hose back along the frame and down the right rear leg. 1/4 inch fuel hose is plenty large, and no need for it to be reinforced. The stuff they use on lawn mowers is fine.
Here's a look at a bypassed Ness plate.
I have always vented my bikes to atmosphere with no filter. I notice that there is more oil on the garage floor with the M8 than with any TC I have owned. Instead of a couple of drops, there is a dime sized puddle and that's with the oil level at half way on the dipstick. Don't know if that means anything
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I did the same thing except I did it by mistake. I first installed an EBS system on my backing plate into a catch can. After that I discovered the Fueling Vented Dipstick and added that as well cause I like design and theory behind it and figured it can’t hurt. I have a 2015 CVO RG with the 110 inch motor and had 52k on it when I decided to keep the bike and do the top end with the Harley 117 kit and SE billet cam plate and high pressure oil pump. I probably would have done the vented dipstick even if I didn’t do the top end but felt it was even more necessary with the added compression. No regrets here and yes, the bike seems happier as do I with the slight added throttle response.
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Yes I have one of my 2018 Road Glide you can tell a difference on a long ride on a long day the throttle response is much crispr
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The vented dipstick does not work as good as venting the head bolts, and venting the trans cover makes it work even better.
Mine is under warranty until March, so as you can see have tied into the stock hose breather bolt hose. If I have to take it to the stealer, then I put the elow hose back on, and no one knows.
I also did this to the bro-in-laws bike (who works for HD) and I ended up riding up there and showing the ones with M8s how I did it.
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When it goes out of warranty, then I will remove this and install the trans cover method.
Mine is under warranty until March, so as you can see have tied into the stock hose breather bolt hose. If I have to take it to the stealer, then I put the elow hose back on, and no one knows.
I also did this to the bro-in-laws bike (who works for HD) and I ended up riding up there and showing the ones with M8s how I did it.
When it goes out of warranty, then I will remove this and install the trans cover method.
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I run the Fueling vented diptstick on all of my bikes. 2 of my bikes i've converted the air breather to vent externally as well. When I asked my HD shop if they liked the idea of a vented dipstick they said "sure - you would breath better if you had a 3rd nostril too" ! It's a little pricey but its a quality peice.
I had one from A1 Cycles and even running my oil a full quart low, it would spit and puke all over the motor. I wasn't going to run my bike that low on oil to fix a problem that probably didn't exist. During servicing, I put in 4 quarts which puts the level halfway on the dipstick. When I clean my air filter, it doesn't look like I'm getting excessive oil in the filter or throttle body. Also, nothing dripping down onto the cam cover. 108,000 miles on the bike and it hasn't exploded yet from not having external venting. Some people will argue it will help the sumping issue on the 2017-2019 models (mines a 2020). But if that's the case, a vented dipstick is just a band-aid. In my lowly opinion, not worth it.
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Scott7d - I also had the A1 vent on my bike, and it did the same thing. It's to close to splashing oil, I believe, and that the putting the vent in that cover that sits behind the rear cylinder is the best place for the vent.
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