Stock Air Box Back On Re-Did, Re-Rout EBS Catch Can Set Up

[Bill G]

OK I did your mod,

Looks Great..

Bill G

[Bill G]

All 1/4" with barbs on the fittings . Will not come loose. I show a pic of the holes I drilled in the air box the smaller is for a drain may not be needed but hay I was in there

, 1/2"hole for the 1/4" ID fuel line. Plugged the back of the paper filter were the stock line went in. All went well and $28 at Ace they had it all.3 ft of 1/4" fuel line 2 mini clamps 2 90* nipples 1 Tee all with barbs. Thanks Bill G.

These new breathers do not breath as much as the twin cam going by what I felt before the hose install at the breather bolts now it is all out the hose to atmosphere.

I used a rubber plug on the back of the filter to seal the hole. That hose looks sweet...

Bill G

[hddocfl]

Looks Great..

Bill G

Thanks for the Mod.

[Trampas]

Hey hddocfl, what did you use for a catch can, didn't see any pics of that, I seen where you spent $28 at Ace hardware for parts, don't think they have any catch cans but maybe they do, just curious what you are using for a catch can. I do like this simple set up by the way.

All for now Trampas

[Bill G]

Hey hddocfl, what did you use for a catch can, didn't see any pics of that, I seen where you spent $28 at Ace hardware for parts, don't think they have any catch cans but maybe they do, just curious what you are using for a catch can. I do like this simple set up by the way.

All for now Trampas

Trampas,

I got the feeling hddocfl left the line open ended from his rite up. Some guys choose to do that.

I had a fella on another forum tell me the catch can was unnecessary, I disagree. I don't like the line open ended myself.

My reason is the oily vapor can blow back and get on the bottom of your bike over time. This attracts crime and dust that then sticks to the underside of your bike.

The catch can filters the vapor through foam allowing the vapor to go out the top of it clean ( through the little holes around the top).

The oily water vapor sludge stays in the catch can. You just got to service it once in a while. Fast and easy to do.

Maybe hddocfl will chime in on weather he did or did not add a catch can or a filter.

On another note my set up with the catch can is working out great and working flawlessly.

Ride Safe My Friends,

Bill G

[hddocfl]

Hey hddocfl, what did you use for a catch can, didn't see any pics of that, I seen where you spent $28 at Ace hardware for parts, don't think they have any catch cans but maybe they do, just curious what you are using for a catch can. I do like this simple set up by the way.

All for now Trampas

I ran it right to the atmosphere no catch can, I have done it this way for decades never had a problem the hose extends down low of the frame. Doc

[hddocfl]

Picture is worth a thousand words. Doc

[hddocfl]

ANOTHER

[hddocfl]

Right now with only 200 miles on this bike there is no oil in the hose and or at the time I did this mod (Thanks Bill.G) there was no oil in the throttle body bone dry. I rode it today and still no oil and breathing good thru the hose about 20" long. My other rides with the same type of breather to ground would always have a drip at the end of the hose, never on the bike. Time will tell if I need a catch can it will get it. Thanks Doc

[Trampas]

Trampas,

I got the feeling hddocfl left the line open ended from his rite up. Some guys choose to do that.

I had a fella on another forum tell me the catch can was unnecessary, I disagree. I don't like the line open ended myself.

My reason is the oily vapor can blow back and get on the bottom of your bike over time. This attracts crime and dust that then sticks to the underside of your bike.

The catch can filters the vapor through foam allowing the vapor to go out the top of it clean ( through the little holes around the top).

The oily water vapor sludge stays in the catch can. You just got to service it once in a while. Fast and easy to do.

Maybe hddocfl will chime in on weather he did or did not add a catch can or a filter.

On another note my set up with the catch can is working out great and working flawlessly.

Ride Safe My Friends,

Bill G

Bill I agree with you, you are like me, keep the underside as clean as the top side

All for now Trampas

[Trampas]

I ran it right to the atmosphere no catch can, I have done it this way for decades never had a problem the hose extends down low of the frame. Doc

Thanks for the pics, if I do it I will do a catch can, just me I guess, keep it clean

All for now Trampas

[hddocfl]

Well after another 50 miles the oil has showed up at the end of the hose, just like all my other bikes have done, No oil showing on the frame and after sitting all night not a drop on the floor, My other rides would always leave a drop maybe with more miles this will happen. Thanks Doc

[hddocfl]

Well after another 50 miles the oil has showed up at the end of the hose, just like all my other bikes have done, No oil showing on the frame and after sitting all night not a drop on the floor, My other rides would always leave a drop maybe with more miles this will happen. Thanks Doc

Well after 450 mile the bike is marking its spot one drop on the floor today, still clean frame and breathing good, This mod is a keeper. Doc

[Capt.Bob]

I like the catch can option but I had something happen these past couple of days that makes me a bit leery of the mod. The reason is that the large screw holding on the M8 air filter cover on happens to screw into a brass fitting that is imbedded in plastic in the middle of the stock Harley M8 air filter. I was attempting to examine my air filter to see how much oily blow-by was going into that area with 2200 miles on the clock of my 2017 and the darn brass fitting had stripped out of the plastic. I had to take it to Harley and they did what I think what I would have done which was to have one person pulling on the air cleaner housing and another unscrewing the bolt from the loose brass fitting. If I had done the mod that some are talking about in terms of punching a hole in to the bottom of the metal air filter housing, I am not sure how receptive the dealership would have been to performing the work under warranty where they subsequently ended up replacing the defective air filter and did not charge me for any labor to do the repair.

[Bill G]

I like the catch can option but I had something happen these past couple of days that makes me a bit leery of the mod. The reason is that the large screw holding on the M8 air filter cover on happens to screw into a brass fitting that is imbedded in plastic in the middle of the stock Harley M8 air filter. I was attempting to examine my air filter to see how much oily blow-by was going into that area with 2200 miles on the clock of my 2017 and the darn brass fitting had stripped out of the plastic. I had to take it to Harley and they did what I think what I would have done which was to have one person pulling on the air cleaner housing and another unscrewing the bolt from the loose brass fitting. If I had done the mod that some are talking about in terms of punching a hole in to the bottom of the metal air filter housing, I am not sure how receptive the dealership would have been to performing the work under warranty where they subsequently ended up replacing the defective air filter and did not charge me for any labor to do the repair.

The hole in the bottom of the air box is drilled through plastic. The factory air box is plastic only the air box cover is metal. All the guys at my Dealer here in California includeing the owner thinks the mod I did is great.

A few of them are thinking of doing it to there own M8. The hole in the bottom of the air box is really no big deal and really no diffrent than a drain hole and causes no structural damage.

With that said, every dealer is diffrent. I don't think this mod would be an issue but I could be wrong.

I have had my AC cover off a lot with no issues. It makes me wonder if your AC cover bolt was overtightened or possibly cross threaded a little from the factory.

Ride Safe,

Bill G

[Capt.Bob]

The hole in the bottom of the air box is drilled through plastic. The factory air box is plastic only the air box cover is metal. All the guys at my Dealer here in California includeing the owner thinks the mod I did is great.

A few of them are thinking of doing it to there own M8. The hole in the bottom of the air box is really no big deal and really no diffrent than a drain hole and causes no structural damage.

With that said, every dealer is diffrent. I don't think this mod would be an issue but I could be wrong.

I have had my AC cover off a lot with no issues. It makes me wonder if your AC cover bolt was overtightened or possibly cross threaded a little from the factory.

Ride Safe,

Bill G

Bill, The service manager at my local HD dealership had never seen this particular issue before on the 2017 M8. On my 2016 TGU, I had a defective radiator and when the tech was pulling it out of the plastic housing, a similar type ferrule had stripped out of a painted part and I was told that it could take up to a month to get a factory-painted replacement. Fortunately, Harley came through in about 9 days and they had me up and going in a total of 10 days downtime.

I am not trying to over-hype my concerns but don't have enough confidence yet in the new M8 drivetrain with only 2300 miles to mess around with things that are partially internal/external like the induction system. I see the logic in not venting oily waste gasses back into the engine but OTOH, Harley engineers have reportedly elected to vent waste gas into the engine from two separate sources so I am not sure if the experimentation is worth the hassle for myself. Just a personal choice and one that each of us gets to make

[hddocfl]

Harley engineers have reportedly elected to vent waste gas into the engine from two separate sources so I am not sure if the experimentation is worth the hassle for myself. Just a personal choice and one that each of us gets to make

I must be missing something as I only have seen two breather bolts that vent into the intake. Please Explain were the second one is as I have not seen it. Thanks Doc

[Capt.Bob]

"A breather assembly is mounted to each cylinder head to prevent buildup of pressure caused by the downward force of the pistons. Burning crankcase vapor eliminates the pollutants normally discharged from the crankcase...

In the breather assembly, the flow of air passes downward through the labyrinth where most of the oil is separated from the air. It then moves upward through the breather element (4) where the remaining oil is removed. Two small holes in the bottom of the breather housing allow the separated oil to drain back into the crankcase." Page 4-12 of the manual.

The main emphasis of the Crankcase Ventilation paragraphs are highlighting the vapor passing through the breather bolt. However, there seems to be some mechanism with the "two small holes" for some oil being scavenged back into the crankcase? My concerns remain that this whole system was likely engineered for optimal oiling as well as meeting emission standards and it is possible that altering the oil and oil vapor strategies may have some unintended consequences that only engineers could ferret out? The M8 engines have already had some past history of engine oiling problems that were most likely attributed to cobbled up manufacturing but that remains to be seen given the check engine oil lights that continue to be reported? I personally do not want to experiment with certain aspects of the engines performance that might contribute to unintended outcomes. Again, this is just one person's opinion and I didn't stay at a Holiday Inn Express last night or go to engineering school so cannot claim any expertise .

[Bill G]

"A breather assembly is mounted to each cylinder head to prevent buildup of pressure caused by the downward force of the pistons. Burning crankcase vapor eliminates the pollutants normally discharged from the crankcase...

In the breather assembly, the flow of air passes downward through the labyrinth where most of the oil is separated from the air. It then moves upward through the breather element (4) where the remaining oil is removed. Two small holes in the bottom of the breather housing allow the separated oil to drain back into the crankcase." Page 4-12 of the manual.

The main emphasis of the Crankcase Ventilation paragraphs are highlighting the vapor passing through the breather bolt. However, there seems to be some mechanism with the "two small holes" for some oil being scavenged back into the crankcase? My concerns remain that this whole system was likely engineered for optimal oiling as well as meeting emission standards and it is possible that altering the oil and oil vapor strategies may have some unintended consequences that only engineers could ferret out? The M8 engines have already had some past history of engine oiling problems that were most likely attributed to cobbled up manufacturing but that remains to be seen given the check engine oil lights that continue to be reported? I personally do not want to experiment with certain aspects of the engines performance that might contribute to unintended outcomes. Again, this is just one person's opinion and I didn't stay at a Holiday Inn Express last night or go to engineering school so cannot claim any expertise .

The venting back to the crankcase on pages 4-12 were done to improve the M8 crankcase breathing system over previous year engines (dump less raw oil back into the throttle body).

A better venting system for sure but it still vents oil and vapor back to throttle body/intake.

The M8 is bigger and has more oil capacity therefore needing an improved venting system as described on pages 4-12. The issue is the cylinders are vented the same as all previous HD motors have been for years now.

These vents have always vented vapor back to the throttle body (EPA requirement no venting crankcase gas to the atmosphere).

Your car has the same requirements also EPA mandated and vents back through the smog related systems on it.

The HD M8 engine does not care how this vapor is vented as long as the engine is vented and it does not know the diffrence. Venting to throttle body or to atmosphere accomplish the same thing and will not hurt the engine at all.

Ride Safe,

Bill G

[hddocfl]

In my own findings I have felt no suction on the vent hoses or the breather bolts that I can feel anyway. I did take a glass of water and stuck my vent hose in it with the stock A/C mod that we are talking about here and only get a small amount of air bubbles in the water, The water does not go down in the glass as to indicate a suction that is measurable that can be see. I would recommend to anyone not sure of this to not do it. I feel it is the right way to go and may later add a catch can but have seen no reason to add one now. Thanks Doc

BTW This mod can be undone in minutes back to stock , only showing a hole in the bottom of the plastic A/C housing.