Crank Case Vent with Pods

[Aequitas4]

After jetting my 97 intruder 1400 and installing pod filters I noticed a lot of noise coming from the front cylinder crank case vent tube. I have searched the forum and found that some people vent it with a long hose down to the ground while others recommend piping it back into the air intake while still others just put a crank case vent filter on the head.

My questions are 1. Why is my crank case vent so noisy... I can even hear it over my exhaust, and 2. if the crank case vent is so critical that people adamantly recommend against plugging, then why does the rear cylinder not have one?

Thanks for the help

[Herb]

1. Every time one of these big pistons goes up it sucks air in and when it goes down it blows air out, that is what is causing the noise.

2. The 2 cylinders share the crankcase so only one vent is required. I think the reason for the vent being on the front cylinder is space. The area around the rear cylinder valve cover is already very crowded and the extra plumbing would make things a lot worse.

[hillsy]

The breather port is relatively small for the amount of air that passes through it - I know with the 1500 if you run them hard it can spit oil into the airbox. I ended up with a hose running straight from the breather down under the engine and exiting near the swingarm pivot. It never spat any oil out but when I had it plumbed into the airbox (stock) it did at times - and the "hissing" would be noticeably louder.

As far as plugging it up goes - I accidently kinked the hose at one point and oil started weeping out of the decomp seal. So, in other words, you need to have this open to the atmosphere.

[Designer]

As Herb points out the noises are from the Air Movement caused by the Pistons Up-and-down movement. There is actually an In-and-out motion to them.

I noticed that the sounds tend to be louder when guys run a small Air Filter attached on a hose close to the Head. Though this "fix" is much better than a simple unfiltered hose dropped down low,.. what you end up with is considerable Oil Residue that is condensate from the Vapors expended.

May I suggest this.

As does the Stock Setup, this will take the Crankcase Vapors and run them through the Combustion Chamber. Thus, not only is this Cleaner (no oil residue that attracts dirt on the Engine),...but a bit cleaner for the environment ( no dripping on the Road and into the Atmosphere.)


Using the Stock Hoses and some added fittings


Make a hole in the K&N Air filter


Putting this Fitting in the hole made in the K&N Pod Filter

[Aequitas4]

If there is oil in the air coming from the crank case vent, wouldn't piping the air into the rubber on the air filter (as shown above) just put the oil directly into the carb?

I haven't seen any oil visually coming out of mine. Purely curious.

[Herb]

Actually, there are oil vapors and they will condense. One of the reasons for plumbing the vent into the air filter is that it will burn the vapors.

The stock airbox has a drain off of it that has a foam filter on the end of it to drain off any oil that condenses in the air box. It is actually part of the emissions system.

[Designer]

If there is oil in the air coming from the crank case vent, wouldn't piping the air into the rubber on the air filter (as shown above) just put the oil directly into the carb? I haven't seen any oil visually coming out of mine. Purely curious.

As Herb correctly points out, the Crankcase Vapors go into the Carb Throat and into the Combustion Chamber to be Burned. Most of the Vapors are Blowby Gases, Pressurized by the Combustion Chamber that get past the Piston Rings,...what little Oil vapor there is is of no concern.

So,..No worries!

[hillsy]

If there is oil in the air coming from the crank case vent, wouldn't piping the air into the rubber on the air filter (as shown above) just put the oil directly into the carb?

I haven't seen any oil visually coming out of mine. Purely curious.

I think the oil coming out of the breather issue is just a 1500 thing - and only happens when the bike is run hard.

I never mucked around with enlarging the breather hole, but it would probably alleviate the issue. As an anecdote my brother in law mechanic had a Chrysler Voyager that was doing this - spitting oil out of the breather and soaking the air filter. He enlarged the hole going into the airbox and this stopped the problem. The smaller hole increased the pressure which in turn pushed the oil through the hose. The larger hole reduced the pressure so this didn't occur.

[Designer]

I think the oil coming out of the breather issue is just a 1500 thing - and only happens when the bike is run hard.

Uhhh,...nope! Yes,.... ​You are certainly free to think that,...but doing so would be a mistake.

Aequitas4,...when you get a chance read this.

If there is oil in the air coming from the crank case vent, wouldn't piping the air into the rubber on the air filter (as shown above) just put the oil directly into the carb? I haven't seen any oil visually coming out of mine. Purely curious.

As Herb correctly points out, the Crankcase Vapors go into the Carb Throat and into the Combustion Chamber to be Burned. Most of the Vapors are Blowby Gases, Pressurized by the Combustion Chamber that get past the Piston Rings,...what little Oil vapor there is is of no concern.

So,..No worries!

[hillsy]

I think the oil coming out of the breather issue is just a 1500 thing - and only happens when the bike is run hard.

Uhhh,...nope! Yes,.... ​You are certainly free to think that,...but doing so would be a mistake.

So oil DOES come out of the 1400 breather?....and you plumbed yours pretty much directly into the carb?

[Designer]

I think the oil coming out of the breather issue is just a 1500 thing - and only happens when the bike is run hard.

Uhhh,...nope! Yes,.... ​You are certainly free to think that,...but doing so would be a mistake.

So oil DOES come out of the 1400 breather?....and you plumbed yours pretty much directly into the carb?

hillsy, you had best not start another bickering argument and drag this Thread Down.

We see you doing this lately and it is NOT in The spirit of Tech Board.

I apologize to you, Aequitas4,...seems hillsy thinks he's.."the burning bush" ..of the Tech Board and gets real testy when he's mistaken.
Please don't let him turn you away.

[hillsy]

Its relevant to the topic if you are saying the 1400 spits oil out of the breather like the 1500 is prone to do.

How about you clarify what you are saying?

[Aequitas4]

hillsy, I'm not going let you start another bickering argument and drag this Thread Down.

We see you doing this lately and it is NOT in The spirit of Tech Board.

I apologize to you, Aequitas4,...seems hillsy thinks he's.."the burning bush" ..of the Tech Board and gets real testy when he's mistaken.
Please don't let him turn you away.

No need to apologize, I'm incredibly impressed at the number and speed of responses on this board. Its nice to have people that actually have the experience they claim to, and are willing to help and respond. Even if they like getting each other riled up every once in a while for spirited argument or just for grins.

[navigator]

Any bike will spit oil through the vent tube, especially if it is run hard and most certainly if it is overfilled with oil.
All stock setups route the vent tube to an airbox, outside of the filter, and provide a drain tube.
My suggestion with pods would be to run a long hose away from the engine and leave the end open to atmosphere.
JMO

[hillsy]

Any bike will spit oil through the vent tube, especially if it is run hard and most certainly if it is overfilled with oil.
All stock setups route the vent tube to an airbox, outside of the filter, and provide a drain tube.
My suggestion with pods would be to run a long hose away from the engine and leave the end open to atmosphere.
JMO

I'm not 100% with you on any bike spitting oil out the breather - there's a lot of variables in cylinder configuration, size, placement of the breather, etc. But overfilled with oil / fuel in the oil will definitely not help. Also blow by can be a big factor.

I had a KTM that wouldn't start and it was blowing HEAPS of oil out of the breather - ended up being flaked Nikasil on the bore which was negating compression and causing massive blow by.

Co-incidentally it had the breather pipe plumbed into the intake manifold as standard

[FallenAngel]

flaked Nikasil

Whats That I havent heard that term before
I my self would rather have the vent after the carb
Most engines do have some "Blow By" as a result of the engine just running and getting hot even new engines it just isnt noticed because of Positive ventilation

Of coarse a poorly operating combustion chamber will increase the blow by

[hillsy]

flaked Nikasil

Whats That I havent heard that term before
I my self would rather have the vent after the carb
Most engines do have some "Blow By" as a result of the engine just running and getting hot even new engines it just isnt noticed because of Positive ventilation

Of coarse a poorly operating combustion chamber will increase the blow by

Nikasil is an electrolytic coating they use on cylinder bores. It theoretically doesn't wear out / is far more durable than the steel in a regular sleeve.....unless it peels or flakes off of course

[FallenAngel]

Aaah its a coating

[hillsy]

Aaah its a coating

Yeah - the idea being the rings and pistons wear out before the bore does. They first started using it in 2 stoke motocross bikes but it soon moved into 4 stoke territory.

It kinda makes sense in dirt bike world where engines are pulled down regularly for top end rebuilds - far easier and less expensive to replace a piston and rings than to rebuild / bore out a sleeve....then have to replace the piston anyway.....

[Designer]

Any bike will spit oil through the vent tube, especially if it is run hard and most certainly if it is overfilled with oil.

Oh so true, Navigator. ANY bike can spit oil through the CrankCase Venting Tube if it's overfilled. Thus said,...what you say is 100% correct.

All stock setups route the vent tube to an airbox, outside of the filter, and provide a drain tube.

Yup, It's a standard setup with Intruders.
I, and several others, have been running the Crankcase Venting Set Up I outlined above for their Pod Air Filters. I have never read any complaints about how it works or about running the Vapors/Oil back through the Combustion Chamber.....Zero.