A Royal Enfield forum for the people

[OlBilford]

Ok,lads...this may be an ignorant question...but I don’t quite understand the purpose of it, I do know that they will on occasion puke oil...which is part of the question I’m trying to puke out myself, sometimes I see fellas add a fancy little air filter in lieu of the hose to the air box set up they come from Chennai with. Is that a good idea,with the fact that it perhaps will blow as well as suck? What could improper crank case ventilation do ? I’ve seen fellas vent theirs into old cans or bottles fastened to their bike in any array of ways,wouldn’t that make more sense than into our air box? I know all of us have gotten a case of oil filled filter ... if anyone could help clear this up for me,I’d take ya out for a couple tacos...because it seems to be my focus of thought today...
Obd

[swamp2]

Well... I'm no expert but, when the piston travels down the bore, it is displacing a bunch of air somewhere - like into the crankcase. That pressure has to be vented off somewhere. Dumping it into the airbox where it can just be sucked back into the intake is the "cleanest" way to get rid of it. So of course, the EPA likes this best, rather than dumping it into the atmosphere. Since there's always some oil sitting around in the crankcase, that breather air will always have some oil particulates in it. If there's a lot of oil down there - like from a leaky oil pump that lets oil drain down there when the engine isn't running - it's gonna get blown out with the air pressure.

This is all pretty normal stuff for those used to dealing with old British crap!

[gashousegorilla]

Yup , what he said ^^^^. And you also get blow by gasses past the piston rings when the mixture lights up. Crank gases are mixture of nasty shyte. Water , oil vapor , acidic byproducts of combustion and etc. You have to get rid of it , or it will foul your oil quickly. And you'll loose power and start blowing out seals if you don't, and the pressure builds up. The piston goes down the cylinder easier if it doesn't have to fight a positive pressure. Dragsters and hot rodder's will even hook a vacuum pump up to the crankcase, to get negative pressure and gain a couple/ few more HP. Or you can also hook up check valve and tubing arrangement into the head pipe , and as the exhaust gases flow by, it puts a little negative pressure on the crank case and evacuates it... a Crank Case EVAC system. Every little horse helps when your racing, type thing.

If you put a filter over the vent, like the K&N jobs ... right at the vent , or at the end of a long hose . It will "work ", but you will have to clean that filter very often. It will get clogged up with shyte pretty quickly . Which ain't good , because if it becomes blocked, your crank case won't vent correctly and your pressure will build up.

Some guys have put a PCV valve on the Enfield Crank case vent... so it will act as a one way valve. Letting air out and not in. Running around on my bike with a vacuum/pressure gauge hooked up to the crank case and a PCV valve hooked up ... the biggest PCV valve I could find. I would get positive pressure in the crank case at high rev's. So I nixed that Idea. And plus, PCV valves also get gubbered up with shyte in them over time.


What I do , is ... Hook up a long Clear hose from the crank case vent , and run it up towards the seat, and then loop it back down and point it over the chain. With zip ties ... not crimping the hose. So instead of fouling my air and fuel mixture with nasty crank case gases ... I put it on the chain instead . Haha ! Or you can just point it off to the side of the chain a bit , or even out the rear behind the fender. When that motor is running and at any kind of RPM... all your getting is air blowing OUT , and not getting sucked back in. Put your finger over the vent , and rev the engine... you'll see what I mean.

I should add that I do not use the stock air box on my bikes for the intake . But if you do, and want to re-route your crank case vent hose. Plug that hose pub connection on your stock air box after you take it off. Or you will be sucking in unfiltered air.

[Tim]

This is great stuff guys. Swamp2 it's sounds like you might be an expert!

If you put a filter over the vent, like the K&N jobs ... right at the vent , or at the end of a long hose . It will "work ", but you will have to clean that filter very often. It will get clogged up with shyte pretty quickly . Which ain't good , because if it becomes blocked, your crank case won't vent correctly and your pressure will build up.

The crankcase filter is extremely popular ( because it looks cool). But I get the impression people put them on and never think about it again. When you say it gets dirty quickly, like a riding season, or more like a month?

Some guys have put a PCV valve on the Enfield Crank case vent... so it will act as a one way valve. Letting air out and not in. Running around on my bike with a vacuum/pressure gauge hooked up to the crank vent and a PCV valve hooked up ... the biggest PCV valve could find. Should that I would get positive pressure in the crank case at high rev's. So I nixed that Idea. And plus, PCV valves also get gubbered up with shyte in them over time.

Royal Enfield actually added a check valve to the breather hose on Iron Barrel models. Black hose, no way to check the "muck" level

What I do , is ... Hook up a long Clear hose from the crank case vent , and run it up towards the seat, and then loop it back down and point it over the chain. With zip ties ... not crimping the hose.

Why don't you "duckbill" your hose? Easier to clean? This is also an extremely popular thing to do on older bikes. I'm kinda concerned that I've been mis-leading the flock.

[OlBilford]

blinding me with science!! Hahahha awesome,thanks guys that has helped clear up a lot for me. Those little filters look trick,but I sure was suspect, knowing the nature of people, they would cram a kazoo in the hole if it was thought to look cool...performance be damned. I’m sure this is not the end of my inquiry...but I am going into this armed with a better understanding...better get my taco money out...
Bilf

[gashousegorilla]

This is great stuff guys. Swamp2 it's sounds like you might be an expert!

If you put a filter over the vent, like the K&N jobs ... right at the vent , or at the end of a long hose . It will "work ", but you will have to clean that filter very often. It will get clogged up with shyte pretty quickly . Which ain't good , because if it becomes blocked, your crank case won't vent correctly and your pressure will build up.

The crankcase filter is extremely popular ( because it looks cool). But I get the impression people put them on and never think about it again. When you say it gets dirty quickly, like a riding season, or more like a month?

Some guys have put a PCV valve on the Enfield Crank case vent... so it will act as a one way valve. Letting air out and not in. Running around on my bike with a vacuum/pressure gauge hooked up to the crank vent and a PCV valve hooked up ... the biggest PCV valve could find. Should that I would get positive pressure in the crank case at high rev's. So I nixed that Idea. And plus, PCV valves also get gubbered up with shyte in them over time.

Royal Enfield actually added a check valve to the breather hose on Iron Barrel models. Black hose, no way to check the "muck" level

What I do , is ... Hook up a long Clear hose from the crank case vent , and run it up towards the seat, and then loop it back down and point it over the chain. With zip ties ... not crimping the hose.

Why don't you "duckbill" your hose? Easier to clean? This is also an extremely popular thing to do on older bikes. I'm kinda concerned that I've been mis-leading the flock.

Yup, mostly because the filters look cool. And yes, they put them on and forget it. They are really for catch can systems or to to be put on valve cover's on V8's ! Haha ! How often should you check and clean them ? I say OFTEN ! Yeah, at least at every oil change I would say. And it depends on how the motor was used ... was the crankcase ever over filled with oil ? Was the motor ran at higher rpms a lot ? The higher the rpms the more crank case pressure and gases and nasty-ness you will produce.

I have no experience with that duck bill thing on the Iron barrels Tim. To me it looks like a very primitive form of a PCV valve. But , yeah... I would pull that sucker off and check and clean it often to . Every engine is different, and that duck bill I'm sure was designed for the Iron barrel motor. The UCE has a bigger crankcase then an Iron Barrel , because it has the trans installed in it. So the crankcase pressures built up inside each will be different . The UCE in theory should develop less pressure. There is no check valve system in the UCE motor or any positive crank case ventilation system . Just an air and oil separation labyrinth chamber behind the right side cover... and a very small , if any , amount of manifold vacuum in the stock air box. .. I measured zero. So the crank case gases are just basically pumped into the stock air box and drawn into the intake . FREE and OPEN and UNRESTRICTED inside that air box so that the pressures in the crankcase can not build up.. that's how it was designed. I don't want anything at the end of my hose that will potentially restrict it. I would do anything to gain a HP or two out of these motors ! Haha ! And I did a lot of experimenting with the vent and my personal conclusion is to keep it open ... with a long hose in a loop .

[OlBilford]

So, today I was out and about and I happened to be fingering thru a magazine that had an article about venting crank cases on 70s era Norton’s...the author was suggesting reed valves, can I assume this is the duck bill, Tim?I found it odd that I’m curious and now I’m being bombarded with great info....I love the lively debate it’s brought to our young forum as well....hahahha

[Tim]

So, today I was out and about and I happened to be fingering thru a magazine that had an article about venting crank cases on 70s era Norton’s...the author was suggesting reed valves, can I assume this is the duck bill, Tim?I found it odd that I’m curious and now I’m being bombarded with great info....I love the lively debate it’s brought to our young forum as well....hahahha

This is the duckbill, basically a hose flattened on one end. I thought Gas was saying he didn't use a duckbill. But after reading it again his "crimping" doesn't have anything to do with the duckbill.

[Tim]

the best part is, this BADBOY is a factory part!

[gashousegorilla]

And I bet that duck bill makes a little farting noise on the Iron Barrel to ! Hahaha !

You can drive yourself nuts with this stuff Olbill... and I have tried them all on the UCE. Just remember that puking oil is not an issue generally on the UCE's . Harley's, Nortons and etc. Yup ! Maybe even Iron Barrels ? It is ONLY an issue when there is too much oil in the crankcase ... and it will self discharge once you hit the higher RPM's. It's up to you where you want to send it, when and if it does.