Breathe baby Breathe

So ive been planning to get the moto breathing better for a while... ive been chatting to mrZ32 about it too.

This set up was done at TAVERNER MOTORCYCLES in brisbane, Australia.

Breathing the top end is important because it relaeases all the presure built up in the engine and lets the engine rev smoother and removes the thick oil filled air from the engine.

both tappet covers were removed drilled an tapped, new gaskets and an inline oil/air seperator

Ive already noticed the engine performance has increased and it is reving smoother

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So I assume all of those components would be available available to carry out this task ourselves.

Seems like just drill the hole the right size for the fitting, fit some rubber washers to seal, attach the hoses to the filter and bobs your uncle, a weight off the chest, is that right?

It's not something I'd be jumping into without more knowledge on it but the mod seems pretty straight forward which is always a bonus

Yes, can just imagine somebody getting an extra long fitting and jamming the cover back on and wondering why their bike isn't running right

Haven't looked at the breathing system on my bike yet. Having said that, does that separator work as a one way valve as well to try to run negative crankcase pressure? Is the intake vacuum all that's there for extracting the bad on the stock set-up ?
Next question would be where did you purchase said separator?

Looks like a clean set-up.

Do you have any more pics dude? Are both cylinders running into same breather. Where is the catch tank and what are you using? Or is the oil just running back into head?

Ill post some new pics as soon as i can so you can see the actual system with the seperator... and how its all linked

This system works... no leaks and a power increase... its smoother too... all racing engines, any type, are heavily breathed

I see that you're familiar with Norton's. Crankcase breathing problems, pumping loss, is something to consider with 360 degree vertical twins. The best mod to be done is reed valve on the bottom rear of the crankcase to eliminate the pumping loss and run slight vacuum. I here it does wonders for top end oil leaks and gives a few more ponies. One way valve in the timing side breather hose helps if not going whole hog and machining case.

Are there any similar gains to be made in our SD motors? Maybe not as good neutral crankcase pressure as a 90 degree V engine but still nowhere near as bad as our Norton's.
I thought the top end would breath through to the bottom end by the chain-ways. New breathers should allow a bit of a flush of the old "air" from the top end.
Couldn't you also use the separator on the line from the bottom end?
Now you've got me curious, I'm going to have to spend some time in the shed this weekend.

Thanks for the info,
Will

Did a full day of riding today, at the end of a second tank as i come home.. not a drop of oil out the breather or in the "catch-tube".

Was a great ride... the bike is reving so smoothly creating great front wheel lifting power (no clutch)...

Today the duke scarded me today, just like the first time i rode it

Hey mate... Just flew back in from the mine site. Didn't have reception. But wow you have out done yourself... How much all up did it cost you in parts?

Put together an inventory list... Would be keen to do this after my last exam... Few beers at mine if your keen.
Very nice job.

I am considering taking it a step further and using the sas ports to act as a passive vaccuum pump too.

Let me know when you are ready for a dyno day one weekend as I'm looking foward to getting the dvs off the ground too... Can't wait till the 5th of July with our track day though... Lakeside is tight enough so that no r1 will have enough straight to get away... However I'm keen for some practice in the mountains:D

Indy,I have also been doing some R@D on negative crankcase[cc] pressure .I run the cc vent line up about 24cms to the ktm pcv valve then up to a tee joint which then goes to front and rear original KTM SAS cylinder head ports.There is a lot of suck from these ports from the exhaust flow which are also one way valve set up which pull air from the cc.Have tested bike for 4000kms and have not had a problem,just a quick free revving motor.Have not used any oil or blown smoke through exhaust and regularly check plugs and SAS plumping for oil but all is clean so far.Just something to think about.Cheers

Mr z32 has been thinking along the same lines as way you've done, my set up could be used in conjunction with your to create a perfect setup

I can understand not venting into the airbox but I'm not clear why top end breathing is required given that any spaces volumetrically contiguous with the crankcase are vented by the OE breather. Any spaces not contiguous with the crankcase will not be pressurised and not require venting. Or is top end breathing instead of, rather than additional to, the OE system better?

Just had a thought.I wonder if the oil tank vent line that runs to the top front rocker cover can be vented through a small filter.I may tinker today me thinks.Cheers

Silverbear pm me your email and ill send some more detailed pics

I even have a cool diagram that i did in ms paint lol

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Now post it up... Ya Lazy barstard! Lol

Indy I have to say you have confussed me[But that is not hard].Early on you said you have two separate breathing systems but your diagram has them as one.Called Rocket Industries today to order the oil/air separator but was told they don't sell one.They do sell a aeroflow profilter for fuel only so have you a part number or something to help me find this part.Cheers

ill get the part number for you, the systems are seperate but breathe into the same filter, because its a two ended filter.

If the hoses went into a t piece then into one filter then the system would be joined... they are seperate because both systems can breathe individualy of each other....

Does that make sense??

Hi guys,
This looks very interesting, I've been reading this avidly and am not sure if I am barking up the wrong tree so I thought I'd give it a whirl and ask a few questions.
Indy is the synthetic braid that you are using -8? I saw some today at EnZed and was curious.
What size are your NPT elbows are they 3/8" to -8JIC or 1/2"?
I also had a crack a a diagram before I start so that you guys can tell me if I'm way out. I've just made it from what I've read on this post.
Any feed back would be wicked as I'm more used to Hydraulics and air systems not motors.

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Cheers for that. I was just poking in the dark with the SAS running. I thought to pinch Silverbear's idea and use the SAS to create vacuum on all the breathers.
I mean one way valve when I say check valve, just get used to a different terminology.

Here is a revised diagram. Is this more along the lines of what you guys were talking about? Eg, SAS as Vacuum?

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I ran my CC breather the other day (before seeing this post ) and found that the one way valve had a lot of oil emulsion on it. Have any of you guys found a similar thing?

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I cleaned it all and got it wsorking fine. Reinstalled without a hassle.

I hope the hose is long enough as I scavanged it off the SAS

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Oh... And I went to a "performance Harley" place today... They couldn't tell me anything. All he kept saying was that Harley have no beathing issues and that "The two motors are completely different" As soon as I said the bike was a different V-Twin he shut down, shame.

It's all good,I got the double ended filter, just no extra info on breathing the top of the motor.
The old girl has done 22k but is only 2k past a major service as I couldn't be sure it was done befoe I bought it. I'm a little worried about the oil as, like you said oil=blow through. I'm hoping the miliness is just condensation from the air box as it looked darker in the Motobox.

based on the fact that it's not a motorcycle specific oil and contains friction modifiers and long chain polymers which glaze up the friction plates on the wet clutch causing it to slip.
not that it matters but i "prefer" shell VSX4, it's made for bikes with constant mesh gearboxes, wet clutches and small high revving valve trains, save your oil additives and general purpose oils for your smoky HQ holden mate, they have no place in a modern bike. want something better than "decent"? go buy neo, at $50 a litre, or amsoil, at about $25, both fully synthetic, both have much higher shear strength than most decent engine oil, overkill for what we use our engines for but that's the other end of the choice range for oil, change it often, use the CORRECT oil for the application and any decent, (there's that word again) oil will do. No need to get offended but really, what applies to harleys doesn't necessarily apply to bikes that are more performance orientated, they have a dry clutch, separate transmission and pushrods for fooks sake, they redline at what? 5000? if that! and they're (except the V-Rod) air cooled, chalk and cheese.

paul.

VRSCR ? round corners? you sure you can ride? maybe you're the one who needs training wheels on your girls bike. finished trying to convince me how fantastic you are now?
oh yeah, sweeping the floor and getting coffee for dad doesn't really build experience in a performance bike shop.

http://www.lucasoil.com.au/content/view/97/127/

http://www.lucasoil.com.au/content/view/96/128/

i looked on the lucas website and there's a HD stabiliser and a SYN stabiliser, couldn't find anything that said it's suitable for wet clutches, but it does "seal the cylinders to stop oil going up to be burned" thought piston rings did that?

as indy may have now pointed out... his dad was head of the pit crew for one of the lead racing teams (6.5 second drag bike).
the obvious statement is that a harley is a v-twin... and a lot of the ideas that are used on the high end drag bikes can be used quite successfully on our bikes. Maybe not all as effective on our bikes as the harley motored (due to superior design etc) but will still work.

All modifications are done with a weigting on them... whether it is extra money for hp, less reliability, more maintenance, more finachy etc... everything comes at a cost. Obviously we cant go to the nth degree like a drag bike (as we need to last for hours of hard riding as opposed to 6.5s)

yes, with wet clutches it is not normally advisable to use a friction modifier... you can get around this by using different types of clutch plates or greater clamping pressure. However on the sd, it is not a clutch designed for stupid amounts of torque or power and are more of a precision piece instead, unfortunately they are known to have issues with the clutch plates glazing over... to the point that even top end motul oils are know to cause this.

the v-rod does recommend the lucas modifyers and is a wet clutch (and the whole engine is a porsche design), so i would think that the plates are different to ours. The v-rod series engine is actually pretty impressive design...

and as for push rods... there is nothing wrong with a push rod... corvette zr1... 475kw monster... made porsche and nissan look stupid when they were fighting over a second or so around the ring... the zr1 did it almost a whole 10 sec faster than both.

most ideas coming from indy have come from proven and perfected methods that go way beyond bolt on accessories.. doesnt hurt taking them in... then you can decide whether you are happy to accept the trade off for the increase... in the end it is your motorcycle.... you have to decide what is important... whether you are happier to have a revvier engine but have to empty out a catch can from time to time... etc.

just because you may not agree that it is the way you would go about gains... doesnt mean that it is the wrong way to do it.

be happy that someone else is paving the way with their bike... letting you know the results of it and even wanting to share the ideas with you.

Regards

J

PS: now where did i put my pain killers

"But you probably ride like rubbish, so who really cares".Loony what have you been drinking or snorting you naughty little boy.That is just embarrassing ,now go to your room and sleep it off.cheers

the harley xr1200 in its performance guise can be quite quick around the corners... not as easy as the sd but im sure it would have no prob keeping up.

and as not knowing his way around the shop... there is multiple bikes that indy has stripped down and built it back up from scratch... with a very successfully raced norton in there too (obviously vintage series).

i think anyone is going to get annoyed when someone says 'your doing it wrong' especially when there is no evidence to back it up (eg breather or removal of flies). There are a lot of people who know how to do an aweful lot on here... quite often i think it is communication barriers... internet blows for explaining an idea... then someone else may mis-read or mis-interperate what has been said... then an agument will arise and everyone gets personal

looney, what i will say is that a personal attack was not needed about the sweeping up stuff etc... nor was the comment from indy about doubting your ability to ride.

but i guess it must be annoying when people write off harley engines as stupid when such a huge part of your life has been spent at the upper echelon of these engines... with serious hp.

I know indy was racing an 8sec harley v-rod that he had developed and built up for the dial in class (huge accuracy and consistancy required) ... yes ofcourse it wont go round a corner but it was never designed too... i would like to see an 8sec superduke try and go round a corner... or any 8 sec bike for that matter... and at that level... huge amounts of skill is required... different skill set but a skill non the less

oh and the sd's are renowned for using oil... ktm thinks that up to 500ml of oil per 1000km is acceptable.

most are around the 100-200ml/1000km

would i use a lucas additive on my bike... no but it does not mean that is is wrong... as long as people know that it has a very high chance of causing the clutch to not engage properly or even slip. (however if you only ever use the clutch to start the bike rolling, and do clutchless shifts i cant really see this becoming an issue (traffic riding is completely different though)... heck it might even work as a cheap alternative to a slipper clutch. lol)

Back before I was single I noticed that a discussion with my now ex would start on which pub to go to, or who was picking up the boys and in no time at all we seemed to be discussing how I had never loved her, why my family sucked and what a tosser I was. The volume would increase from conversational to a furious full on spittle producing scream as this progressed.

So....

I'm just wondering, were the two of you ever married??? (To each other that is)

Don't feel you have to stop by the way, I'm sure I'm not alone in enjoying this thread more by the post.

Thanks

I read your post and every post that has been put on this thread...

Is that a comment on silverbears post or is that your comment about the mod, that was my question?

Tell me what you think of my mod..

it's well done, a neat installation, the aeroquip 90 deg bend on the rear cam cover is mounted where the front cyl breather is but i would have removed one of the front breathers and used that to mount the matching aeroquip bend in the same spot with maybe a tee piece before the one way valve feeding back to the oil tank with the other std return line.. I'm guessing the std breathers that feed into the oil tank are there to keep equal pressure on both sides of the oil pump, as i said before, there's a vacuum and a pressure pump and i don't know enough about dry sump systems to know whether a difference in pressure either side of the supply would effect how the two pumps work together??
I wouldn't think there's an excess of oil volume in the cylinder head or there would be a return line from the rear cylinder head as std and there isn't, which is what leads me to believe the front cam cover to oil tank hoses are there to maintain a constant and equal pressure between the oil tank and crankcase, which by the look of it assists the oil pumps. could be wrong, like i said, i don't have much experience with dry sump set ups, but that's how i'm reading the std set up to work.

paul.

That's what I was thinking about the plastic OEM breathers to beat the dissimilar metals problem with the Mg and Al. And it would look very neat.Is there a reason that I can't Tee off the front breather? Also MrZ I'd like to hear you're thoughts on using the SAS as a vacuum pump.

still waiting to fire it up for the first time since it's rebuild mate.
my 888 has a "krankvent" which is supposed to maintain a low or even negative crankcase pressure, originally designed for harleys which really suffer high crankcase pressures and leak badly due to it, it has made a difference but i'm not confident with the dry sump set up, more research for me before i try it methinks.

paul.

Zero oil in my catch pipe after a 99.6km ride today very happy with the bike and the mod

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here is how i did the route of the crankase breather. Using parts from my SAS removal (hoses, junction bends).

Engine revs much quicker with the rerouting of the one way valve. airbox has been plugged and no more messy grime on the air filter!

very cool

Nice use of the SAS parts and great to hear the mod was a success, the crank and pistons not moving thru that thick oil/air makes a difference and on moto's the smallest difference matters...

anyone else brave enough to have a go??

All the parts are sitting there for me but work is getting in the way.
I'm planning a big week for her when I get the time.
Top end Breathers
STM Slipper
Clutch kit
Water pump upgrade
Bigger tank (Painted and sitting in my bedroom)
Silicon hoses
Nichols Triple
Hopefully in two weeks time.

I'm keen to see the differance in a straight line as you've inspired me to have a go at the 1/4 mile.
Even though I'm crap, if I keep me the same and change the bike I should see a result.

Sorry to show my ignorance but this doesn't make sense to me.
Fitting top end breathers in addition to venting the crankcase. Is this right?
The cam covers are at the same pressure and subject to the same pressure waves as the crank case because its not a sealed system: the cam chain tunnel runs from the crank case to the heads.
Surely venting the crank case is enough? If there is some pumping loss then just fitting a bigger crank case breather would be the answer, no?
Also if there are pumping losses (and there are) the next step is surely to window the bottoms of the barrels.
I know some people have been getting very excited on this particular topic so I'm not trying to offend or insult anyone but I am genuinely puzzled by this one.
Did anyone run dyno figures before and after?

BTW: XR1200s are not even slightly quick. I have a mate who races them in the XR1200 cup and even with all the massive mods done and the huge amount of talent he has fat, middle aged me is still quicker on my SD. Why? Because they have limited ground clearance (the engine/gearbox grounds out), they weigh a lot and don't make much power. Having said that: I don't get why people get so defensive about Harleys. Surely you ride them because you enjoy riding them? There's always something faster AND something slower than you.

Rerouting the OE crankcase breather into the race bellypan and plugging the airbox is all that I thought was needed and have done.

OK. This really got me so I've done some research as i couldn't work out how fitting breathers to the cam covers could make a noticeable difference to the riding experience.
Apparently a major limitation of the LC8 motor is the fact that the crank case is very small and as a consequence suffers from pumping losses.
Increasing the the crank case breathing by any means should free up a significant amount of horsepower (up to 3bhp) and reduce oil loss.

BTW I think the fitment you've come up with is very neat and professional looking. Which, in fairness, given your background, it should do!

OK. I got the information from Richard Albans of TTS who is something of an engine tuning god over here.
Apparently it is a major issue getting serious (drag racing) power out of many twins. Even lower revving (relatively) Turbo and Supercharged Harley VRods have to have major mods to their crank case breathers.
Many car race motors have extra cam cover breathers because its simply easier and more accessible to add additional breathing that way plus, apparently, it can help reduce the effect of pressure waves.

I too am going down the additional horsepower route: I have a DNA stage 3 and an Acra Evo system on.
I have tried high lift cams but it wasn't a success because the heads just don't flow that well so Kev @ Projex is removing the heads for me right now and they are going away to Bob Farnham for a goas flow and skim. Bob is the guy who did the original tuning work for Bracken and KTM on the Battle bikes so he should know what he's doing. Bob will also fit and shim in my high lift cams.
I am getting a modified CP pistons from Tornado in Germany which will raise the compression ratio (including the skim) to 13.6:1
I shall fit the later engine studs which are a bit stronger and less stretchy (technical term) just in case.
If it doesn't make proper power then I will give up, hammer my winkie flat and go wherever is it that beavers make a living.

I don't know.......but others may and I think this option may have been discussed here before.

I hear ya. Other options seem overly complicated to me.

It vents into the airbox, and the airbox has a drain. Easiest option would be to just remove airbox and link them together. If it was gonna pump out out, even on a std bike it would still come out the drain pipe.

I like simple

Ok,

so the point of that post was to say that pumps/one way valve are a better, for arguments sake ill say....

The problems with pump/one way valve is that your running a loss system (not a total loss oil system say with a methol drag bike).

so you will have to keep an eye on the oil... so its not an ideal system for the street... for track work it works...

...this is important....

venting in to the exhaust creates the same problem that 2 strokes have... a build up a crap in your exhaust... eventualy two stroke expasion chambers have to be removed and de-gunked... they loss power if this issue isnt taken care of.

In that artical there is no mention of venting from multipule holes... in the artical it mentions how much volume there is to be moved so in theory multipule outlets from different ends would help that volume escape.

my system is designed that the oil can return from the oil/air seperator as its the highest piont of the system... like a return-able catch can set-up... it acts as a one way valve for the oil...

Personally i dont like the idear of a crankcase being under pressure... its called a breather... expansion and contraction... if it breathes then the pistons on an up stroke can take in air and then push air out on the down stroke... wheather hot or cold air...

Just my opionion...

...my brother just brought a 8 sec comp bike with a spooth engine (65 degree v-twin)on methanol ...it runs a total loss oil system and is breathed from the tappet covers, heads, rocker covers, gear box, crank case and oil tank... all breathed... it only does 8 sec at a time so it just goes to show how important breathing is to an engine..

The best bit... i get to ride it.. spare undies...check

Just trying to figure out if i need to run it before the One way valve, tap the cam covers as well and still make it run to a catch tank to make it track legal

if its a track bike, id tap the tappet covers and just vent everything to a catch can... because you'll always be at high RPM any restriction in the air flow will be negitive...

remember you can always block the tapped head vents of if you unsure

Linga dont forget this piece of the puzzle... oil/air seperator

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Beat me to the punch mate.
Do you have a part number at all as I'm getting typical WA service. They tell me it doesn't exist even when I show them the picture!!

ill have it buy the end of the day.... im sure its from the rocket catologe

Any chance of one of you guys that is pretty up on this thread doing us a "where we are at right now" posts. This thread should prob be added to the MUST READ THREADS LIST. I just added James's Intake mod and feasability study (dual velocity stacks) this looks like another great idea for the SD.

Have completed some vacuum and pressure tests on my bike.Just to put you in the picture my motor uses very little oil,regularly serviced and my KTM trained service mechanic is very impressed with the performance over standard LC8's,so let's say my piston rings are in good order.My KTM one way valve was also cleaned and in good working order and around the right way [triple check].I attached the gauge to a tee piece I made in the vacuum line and proceeded with the test under load on the street reading the gauge attached to my handle bars.With the motor sealed[no rocker breathing and the crankcase plumped to both SAS exhaust ports I had a vacuum reading of .1 to .13 Bars[approx 3 to 4inHG].The only change to the next test was opening both rocker breathers and I was pulling no vacuum at all.It was running with slight pressure but bugger all.Now these are just measurement's when someone asks ,do the SAS ports pull a vacuum.Yes they do but is this a good for the LC8.I'm now going to do 150km test to see if I notice the differents.I also did a measure of the crankcase open to the atmosphere with the rocker boxes open and had no vacuum reading.The motor acted like an air compressor because there was a big increase in crankcase pressure coming out of the breather with the top of the motor breathing.As soon I covered up the rocker breathing the crankcase vent pressure dropped.What does all this mean?I will leave that after some of you smart guy's which we have on this great forum.Cheers

Got the bit to do mine tommorrow and was just looking at the oil tank breathers and was thinking maybe this would be a better option as the parts fit both cam covers as standard...
Just thinking... Jitters before you do something that is a little hard to reverse...
Kev, when you hooked it all up, were the cam breathers tee'd into the Crank breather as well as the SAS?

These are only measurements at this stage lad's.To be fear I have not yet run a full test on the head breathers because I am waiting on a filter.But just up and down my street it registered 0 inHG while with them blocked of it registered 4 inHG of vacuum.I'm now in the middle of some interesting research on MC crankcase venting and should have some interesting data.Once I'm clearer on the subject I will be back.Cheers

Why not just vent all 3 of them to a vented catch bottle. Take out ball and spring from one way valve.

Zero resistance.

so the main crankcase ventilation is from above the stator cover to the air box, the front cam cover has two hoses that vent to the oil tank.
the std oil tank = a catch tank.
the air filter assembly (All of them) recirculates the fumes from the crankcase ventilation through the engines combustion cycle, given the volume of air consumed by each cylinder i would say that is a pretty good source of vacuum for the crankcase ventilation. The fumes consumed by the engine vary, yes, but on the whole i would say if the bike is tuned with the vent hose in place then this would be taken into account by the tune.
I don't get why this mod is needed? even if it's a full on race bike at max rpm for most of it's life, what possible benefit is there to this?

As i see it, from what I understand and have read, if the stock valve is working, and someone said that they they measured 4" of mercury vacuum, then that's as good as your going to get without going to a more complicated vacuum pump set-up.
The pipe could be vented to atmosphere as apposed to the airbox. Opening up the system to breathe better will introduce pumping loss as opposed to running vacuum.


A little something stolen from the Norton site
http://nutterracingengines.com/racing_o ... facts.html
http://www.britcycle.com/products/bunnb ... rticle.pdf

edit
Looks like Silverbear already stated most of this...

I also dont see the benifit of taking your breather out of the air box, surely the pistons are creating a vacum for the breather or am I missing somthing ? I am going to try it and see anyway,if the engine feels smoother and is producing a little more hp without the suction of the engine then surely the engine does not like vacum

there is a lot of theory behind breathing engines.. not just with the LC8... it is more than just one piston up and one down and air passing back and forward....

the air is hot and expands and creates pressure...

the air is full of oil vapour, thick and heavy....


and excessive oil on the crank and moving parts actually adds weight.. thus the use of "windage" trays or crank scrapers which remove heavy oil from the crank to keep it light.... and at 10,000rpm every gram has an effect on the engine performance and crank balance

I was forgetting you are a drag racing guru: but perhaps you ought to tell people that the hot air expanding thing only applies to motors that get very hot very quickly - the temperature in the crank case of a motor running for an extended period of time is pretty stable therefore the pressure due to temperature is pretty stable and is dealt with through normal crank case breathers.

Also the whole idea of scavenging the motor for oil/air and feeding it into the exhaust system: this might be legal for drag racing but there is a reason not even F1 or MotoGp teams do it - its against FIM and ACU regulations. If for some reason something goes wrong you'll be pumping hot oil / oil vapor onto the track and people WILL crash. Don't do it.

i got my popcorn ready

See this is the kinda stuff Motoronin was calling for.

What would you like your poll to ask dude?

does the breather look cool? suggested

loony888 is blind


It looks gooooodddd


meh... don't care


should have been orange


worst mod ever

I'm prety sure the LC8 has a jet that sprays the underside of the piston.


Edit: In fact I'm sure I read somewhere that it has 2 jets spraying the underside of the piston.

It would really be better to know for sure before messing with the crankcase breather system or recommending other people to do so,

There are more negatives to this modification than positives, for a possible gain of 1 or 2 extra bhp its just not worth the risks IMO

Without trawling through posts trying to find the quotes, I'm 99% sure I saw that Bob Farnham recommended extra breathing on the LC8. With all due respect to posters, I'll take the word of a professional tuner held in high regard over here.

yeah, sayin TLS Russ is no longer cool because he doesn't agree is not cool.

look, if people want to experiment with mods that's great, all power to you, but these are not nortons, nor are they harleys, they are very complex for a V twin, in fact i'd go as far as to say that KTM have over engineered the thing in the extreme. the LC8 has two spray jets per cylinder, and spray jets for each timing chain, in essence it's designed to have heavy oil fume soaked air in it. when you add to that there is a vacuum pump that sucks the oil from the bottom of the crankcases and returns it to the tank my concern is that a reduction in crankcase pressure will have a (detrimental?) effect on the scavenger pump. I'm not saying it's a bad idea, although i personally wouldn't try it, not because there's only a very small possible gain but because i believe that mucking with the crankcase pressure is mucking with the oil circuit, and who knows what that can do? it may take time, it may not happen at all but the risk is unacceptable to me, especially having just rebuilt one.
Different engines require different things, harleys are notorious for high crankcase pressure to the point where seals leak and gaskets blow out, but as i said, the LC8 is not a harley, no, i haven't done it, for the reasons above, but there's nothing wrong with a balanced viewpoint, even if it's different to yours.
as for pointing out spelling errors, it was to show that i can be just as condescending as you with your "try to follow along" , glad i made my point.
I think i'm happy to agree to disagree, members will make their own choice, i've done my bit and raised my concerns.

Here is a useful link for proper crankcase breather filters

http://www.thepipercrossshop.co.uk/accessories.asp

you would be a hell of a rider to get it

I will be running 17/40 gearing on mine, got a couple of tricks to try out with the stock airbox in place before i rip it off

pretty confident I will get into the 10s

Me thinks there is some confusion about the issue here!
What happens if a piston goes down in the bore is that it displaces the same amount of, let's call it air, as it would go up e.g. about 500cc.
This needs to go somewhere fast and ideally like in the space of another piston going up so it helps that movement. Hence on IL4's they try to get the openings in between cylinders in the crankcase as big as possible. (Called scavenging)
Unfortunately on the SD with the offset crank pins it doesn't work that way. So evacuating some of the gas helps as the leaks past the piston rings increase pressure in the crankcase, which in turn works against the above.
Now realistic...The HP gains from sucking the air out of the crankcase faster on a road engine is very debatable as doing so is setting yourself up for all kind of drama's.
First keep in mind that the piston needs to go back up and decrease in pressure under the piston will work against that and the "vacuum" under it will increase leaking via the rings.
So what we gained by sucking more air out we lose a bit here. Also seals in an engine are designed to keep things on the inside like oil and gas and water... they need some pressure to work correctly.

All up in my opinion if you are not racing your SD and you are not rebuilding it frequently like you do with a race engine I say there are hardly any gains to have from this and I leave the breathers well alone.
On the other hand what Bob Farnham recommends is increase the scavenging in between the two cylinders decrease pump losses, this will work if it is possible to do this on the SD engine.
Just my 2 cents...

I could do that but he's a busy man and I'd rather leave him working on someones bike than answering a question that Dave can answer for me. Besides I'll be dropping my heads off in a week so I can have a chat then if I still have any questions.

I said I could not see them on the SD micro fiche, not a statement of fact more a question to other members who might know for sure,

You will note Indy was also not sure

unless you can get your facts straight and read what people actually write it would be a good idea to pull your head in

So you're basically saying you don't know a huge amount about the LC8 or you would have known that, shit i dont know fook all and i did Yet you still want people to follow your advice
Where as Bob (yeah we're such goodbuddies now we're on first name basis now) worked on them for KTM for the Super Duke cup and he thinks additional breathing is a good idea. Hmmm let me think about this for a minute... yep I'll go with someone who really does know what they are talking about thanks

I think it's someone else who needs to pull it in

OK girls - enough flirting, get a room

classic!


Now back on topic.

Ordered the cam cover breather from KTM Centre. Finding some nice fittings to join all the various pipes is next on the list.

Plumbing:

Feeds taken from the oil tank, 'Y' piece connector into length terminating in small K&N style filter

Front and rear cylinder cam covers: two breathers each feeding into a 'Y' piece each with length leading to common catch tank vented to atmosphere.

Crank case fed into catch tank vented to atmosphere.

Simples.

what are u using for a catch tank m8?

I tried the basic one today and yesterday, its a little hard to tell but seat of the pants tell me it is reving faster than last time I was out I was suprised by just how much hot air comes out of that little pipe

decided to delete

Just did the basic breather modification today - already posted in diff section - guess i'm one of those that do not want that oily hot air going down the throttle body.

I've been running Amsoil for about 14K miles since buying the bike with 8K miles on it - the pcv valve had ZERO condensation on it and was clean as a whistle. I could see the ball in the valve assbly plain as day and it was spotless. No white gungy oil build up anywhere.

I believe one of Amsoils big test were how easily the oil builds up condensation - so here's a testament to the fact.
Also know that short trips on the bike : for example under 5 miles - to and from work for example add to condensation buildup as engine doesn't really come up to full temps - or the oil doesn't ( something like that )....

The Modification came out better than i expected - hope it works well as i've yet to finish putting the bike together and run it .

1- Relocated the pcv valve closer to the crankcase.
2- cut a short 2" section off of the lower rubber hose that does to CrankCase.
3- eliminated the top portion of the rubber hose from pcv valve that normally goes to top of airbox
4- routed the rubber hose from pcv valve UNDER the throttle cables and to the right
5- installed the "T" connector so the breather and the catch tube are a straight shot - so the breather is on top and any oil has an uphill climb to it and any oil needing to drip down from breather will drip straight down into the catch part of the tube - the part of the "T" connector that does to the crankcase faces to the left obviously.
6- the catch tube runs straight down and into the area behind the battery box out of the way - CLEAN !
It all nestled in the frame so nicely practically doesn't even need any cable ties to hold it in place - though i'll fasten it anyway.
Here's the pic of it.

if you reroute the hose does this not do away with the partual vacum on the pcv? why not take the valve out altogether as it is surely restricting air flow? the hole in the valve itself is only about 8mm

I have been reading this and associated "engine breathing" threads and although I can understand the theory, I am intrigued to know why, if the PCV is installed and working correctly, people are installing a separate filter?

Surely when operating as a one way valve, ie engine vapours out, there shouldn't be any air going back into the engine via this breather pipe, so I cant see the need for a filter! Unless this is to filter the engine vapours being expelled into the environment, which I cannot see being the case.

What am I missing ? (if anything)

the filter is there to stop any shit getting into your crank case, even if the pcv valve is working it could bypass, saying that I have took away the airbox on 2 other bikes, one with a filter and the other without with no ill effect, I am starting to think its a pointless mod with nothing to gain unless the gasses can be plumed into the exhaust or sas system which no doubt opens up a whole lot of other problems

I will be having mine mapped again in May, going to run the bike on the dyno with the PCV connected to the airbox and again not connected with a filter on the PCV hose, only takes a few minutes to do the swap.......
I am not expecting to see any difference, I will however post up the results