Actually, you are only partially correct. Recommended maintenance was determined by using a specific lubricant type, and always of cheaper base oil formulation. That being said, a true synthetic formulation has the potential to exceed the performance of a manufacturer's minimum recommendation, with other benefits.

• Decreased friction
• Decreased wear
• Decreased engine heat
• Efficiency gains
• Smoother engine & transmission (shifting and clutch feel)
• Lower evaporation (less bypass contamination in intake)
• Easier lower temperature starts
• Lower wear at cold start (true syn. thickens less as it cools)
• Increased oil change interval

As I've said before, maintenance intervals are important, but what about all the other benefits listed above? I agree getting the lubricants up to temperature and keeping it there to burn off contaminants is the best way to increase an engine lubricants life. That's why short trips are so hard on lubricants.

 

The first PCV valve.
I don't have anything to add to this discussion other than the fact that what I think we are talking about is positive crankcase ventilation. Not everyone is old enough to remember this (except some of us ancients) but in the "olden" days there was always a black line of sorts down the center of every lane on the highway. At a stop sign it was always very visible in the form of a heavy black deposit on the roadway. This was because of the oily vapor that was discharged out a vent pipe on the bottom of all internal combustion automobile engines. The bottom side of all engines was always a dirty, greasy mess because of this discharge.

If you were a motorcycle rider back then you were aware of the fact that you did not want to ride your two wheels on this black oily line, especially when it started to rain. This was hazardous to your safety.

I think it was somewhere in the late 1950's or maybe early 1960's that all the pollution changes began to first take effect. Usually in California first. One of the initial changes implemented was the introduction of what they then called a PCV valve located usually in one of the valve covers of the engine. It was a rubber breather hose that ran over to the carburetor and discharged engine oil vapor and moisture into the venturi of the carb where it was sucked into the combustion chamber and burned. Some will argue today that this practice is harmful to their engine because this oil vapor will add carbon deposits to the crown of their pistons.

I am not an engineer but I have built and repaired my share of engines over the last 50 some years. I won't take a public stand on whether or not this practice of using a PCV valve in a motorcycle engine is inherently harmful or not for anybody's motorcycle. All I know for positive is that there are few, if any black puddles of oil at the stop signs now.

 

I have noticed this a lot on autos that typically see short trips and don't get the oil hot enough to burn off the moisture. Could this be the same issue? I have never noticed this on any of my motos but my rides are always long enough to to get well in to the operating temp zones.

 

Ding! Ding! Ding!

For all still wondering? Yeah. This you will find if you pull your plugs out and look down into the head. Not easy less you have a very expensive surgical lighted camera. Otherwise, you'll need to tear the heads down.

Yes! The breathers do vent into the intake.
Yes! There will be vapors ie; condensation (H2o), hot air and oil. All will coat the tops of the two pistons.
Yes! It gets burned. Off? No! Though that's what they want you to believe.
Fix is the simplest thing you'll ever do. Right up there with putting air into tires and filling gas tank LOL.
Just remove air cleaner cover and filter. Figure out how to reroute that tube you see going into the combustion chamber and let it breath out and not in.
Note: pointing that hose up, rather than down will allow oil to recycle back in only allowing for condensation and hot air to escape into the atmosphere since oil is heavier than the other two nasties.
Most important fact high performance engine builders will adhere to on every engine they build is that the induction system only takes in cool filtered air. Thus allows less CONTAMINANTS mixing in with the fuel to be ignited. The result is more HP and cleaner engine.

 

Me too.

 

What a pity for me to read this thread. I own a stage II 2013 FLHTK and was considering changing for a brand new one with a M8 engine, reading that the breather problem has been officially fixed by HD by routing the oil mist back in the transmission.

I ride in France where the legal top speed on the highway is 80mph. The combination of oil temp, oil viscosity, RPM and speed will always bring oil in the air cleaner so I ran an after market bypass for years, until the washers of the aftermarket kit started leaking oil. I had a 1200m+ trip to do last week and had to remove the after market kit, I urgently bought a Big Sucker AC and went on the road with an air temp of 98F, riding for hours with the cruise control at 80mph. My right ankle was covered with the garbage coming out the breathers.

I write about speed because if I open the lower air vents of the fairing, and at 98° it is hard not to do so, the problem is accentuated. My opinion is that because of the lack of a real air box, the air vortexes around the intake will spit oil all around, some will go into the intake, some will go in the AC until it is saturated and start leaking in the A/C cover and then on my leg.

I understand that there not enough room for a real air box, like on the VROD I had before, but one can't consider an A/C cover to be an air box. The volume just isn't there to make sure that the air vortex follows a known direction.

Reading that this mickey mouse design continues with the M8 immediately kills any will I could have to change for a newer HD.

I'm really fond of my FLHTK. Here the cops are very relaxed about slaloming between cars and I can handle it in such a way that often even scooters have trouble following me and Aerosmith in the loudspeakers is usually enough to have the cagers to give me some room.

But I need an everyday bike I can count on, one I can use to go see customers without being afraid of smelling oil, dirtying my pants or shoes. I don't want to go again with the after maket solution because, since it is after market, it will always be less reliable than a OEM solution.

Maybe I'll stop ranting about this when I see the new bikes coming out at Fall but hell I'll start looking at Indians in the meantime, I don't know if they have the same problems.

 

Hd did not run the breathers back into the tranny.. It was a misconception based on a non technical magazine writer. I wouldn't worry about the breather leak. It keeps the bugs from sticking to the chrome.

 

The problem is that I have not much chrome on my leg :-) Anyway I'll probably base my choice on what I read here, I don't trust much the salesmen at the dealership, they will certainly say that everything is fixed to convince me and then hide under their desk once the sale is done.

 

Found this explanation about blow-by.

I think I have to either accept some oil mist or stop using a big twin engine with lateral air intake and a small air box.

I guess that the design of the M8 airbox has been done probably with CAD since the challenge of handling both the air flow going into the air intake and the shock waves from the same intake is an extremely complex problem to solve.

I don't think that the OEM is stupid, it must have no other choice but to target a compromise between rider comfort (no oil mist), rider appetite for nice looking engines with a lateral air intake, EPA/Euro requirements to limit pollution and noise/shock waves from the intake.

So the OEM avoids talking about the subject since there is no real solution.

This would mean that changing the M8 OEM air box probably amplifies the problem since after market companies can't have the same level of information about the engine nor suitable design tools.

Looking at an Indian forum I found that some riders are also routing the breathers and complaining about oil in the air filter so the problem must be general to big twins with lateral air intakes.

I will probably stick to HD and ride only with highway pegs

 

One of the good things about the setup is that when the tops of the pistons are going down so are the bottoms..

The problem with motors of this type is that the crankcase volume is not constant since both pistons share the same crank pin and the crankcase size is small.. Another is that cylinder leakage create additional pressure in the crankcase..