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xs650 > > Motorcycle Systems > > Engine > > What do people do with Breather Outputs With No Airbox?


What do people do with Breather Outputs With No Airbox?
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xsjohn
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PostPosted: December 4, 2008, 3:34 pm    Post subject: Re: What do people do with Breather Outputs With No Airbox?

I have an ole double spigot breather from an older engine here...took it apart...there is a plate that covers the vent holes inside and under that the factory stuffed steel wool in it....the wool had hardended goo down deep and I think it was plugging it up.........sure would have positive pressure if that was the case and would could make seals leak....the metal cover inside is hard to get out though.......

The valve I made yesterday was put in this morning......noticable better running....hard to describe but the engine feels less encumbered as its tooling along......sounds like a couple few more MPG and it pulls off noticably better with less throttle.....and pulls my high 5th better too....not the first valve I've made but the first for this bike......

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TeeCat
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PostPosted: December 4, 2008, 6:21 pm    Post subject: Re: What do people do with Breather Outputs With No Airbox?

Jake, I'm thick... Embarassed I still don't see how my induction system could have been a closed one if my hoses vented to atmosphere from stock. I have K&N pods, but also run the Motormite brake check valves with mini breathers on the exits.

metalredneck wrote:
Mine has a gasket, & works great. As far as adding oil, mine is a '74 TX when they changed the oil fill spec, but kept the old dipstick, so mI give her a tablespoon at a time until the level reaches the bottom line with the stick SCREWED IN like a Honda. Any more, & she spews like she caught a dose.

mr... okay... a tablespoon at a time, but screwed closed, yeah? And would the bottom line limit apply to my bike as well, with the cap screwed down? Might I underlubricate? Is two quarts at a change too much? And where does your bike spew from... the breathers?

And I need to make a little gasket.

It's just good to know I'm not alone with these oil questions.


Last edited by TeeCat on December 5, 2008, 10:26 am; edited 1 time in total
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XS919
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PostPosted: December 4, 2008, 10:28 pm    Post subject: Re: What do people do with Breather Outputs With No Airbox?

That stainless steel wool in there is to act as an oil seperator. Oil vapour passing through it will condense on the woll as it goes past and drain back to the sump.

I pulled it all out when I added the catch can. The Catch can does the oil separation job now.

Cheers

Michael
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xsjohn
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PostPosted: December 4, 2008, 10:58 pm    Post subject: Re: What do people do with Breather Outputs With No Airbox?

Noticed today that negative crank case pressure in these really adds to low end torque and frees them up much better at cruise...might not be as dramatic on a stocker that hurts a bit on the real low rpms like below 2500.....should add to MPG ....and plugs were much cleaner....and higher compression takes away from torque above idol to about 2200rpm.......mine pulls off from 16-1800 rpm now like never before.......so basicaly by dropping the compression from 8-5 to 8-1 I lost just a pinch on the high end where I seldom go and greatly inproved the drivability from 1600--5000....quieter...cooler...and much steadier at idol and cruise too....happy....happy

xsjohn
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JeffM
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PostPosted: December 4, 2008, 11:32 pm    Post subject: Re: What do people do with Breather Outputs With No Airbox?

The XS1 carried 3 litres in its crankcase. When the electric start was added in 72 the crankcase was reduced in volume. The original spec of 2.6 litres on the xs2 was based on the same level as the xs1, unfortunately the smaller crankcase contributed to breathing/leaking issues so the spec was dropped to 2 litres. That seems to be about halfway up the stick with the stick just resting in the hole. I think I will scribe a precise line at 2 litres next oil change.

The owners manuals for both my xs2 and Honda CB specify the stick just resting in the hole. These XS's with their roller bearings seem to tolerate (and perhaps thrive?) on low oil levels though.

An O ring from the bulk section at Canadian tire works well as a dipstick gasket.

I'd happily trade my trade my starter motor for an extra litre of oil capacity!!

J
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Jake68
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PostPosted: December 5, 2008, 12:30 am    Post subject: Re: What do people do with Breather Outputs With No Airbox?

TeeCat wrote:
Jake, I'm thick... Embarassed I still don't see how my induction system could have been a closed one if my hoses vented to atmosphere from stock. I have K&N pods, but also run the Motormite brake check valves with mini breathers on the exits.

metalredneck wrote:
Mine has a gasket, & works great. As far as adding oil, mine is a '74 TX when they changed the oil fill spec, but kept the old dipstick, so mI give her a tablespoon at a time until the level reaches the bottom line with the stick SCREWED IN like a Honda. Any more, & she spews like she caught a dose.

mr... okay... a tablespoon at a time, but screwed closed[i], yeah? And would the bottom line limit apply to my bike as well, with the cap screwed down? Might I underlubricate? Is two quarts at a change too much? And where does your bike spew from... the breathers?

And I need to make a little gasket.

It's just good to know I'm not alone with these oil questions.

Dude we may be chatting at cross purposes here..Im not sure...

But a quick recap...

For your "check valves" to work they must open with very very low pressure..enough from merely shrinking the air in your mouth..should be enough for outward flow...having to make any effort with your mouth means that the pressure has to build to that point before the valves open..which is too much for the seal setup on this bike which is designed to work with a fully negative induction induced vaccuum system..

Crankcase breather valves have a flap that takes very little pressure to open because its hinged and has a large service area...sprung cylindrical valves are both too slow and require too much pressure to open...

I am not in the US..so I was unable to check out the valves anyone's talking about..just recounting what I learnt...

I took my check valves out and several leaks stopped and I put the flapper valve in and its perfect...I have even been kidding myself that it ran better until the friggin carbs got crap in them again Smile LOL

I think a lot of people forget this...say you have a pump, a passive pump with two pistons at TDC at the same time and operating no load or valves for instance..and you just vent the crankcase to air...no problem it pulls and pushes the same volume of air..
but an XS motor is not like that its got pressure from combustion and compression leaking past the rings...so without an active suck from induction its very difficult to make the engine oil tight...some have managed it..but the engine is designed for a vacuum ...
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xsjohn
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PostPosted: December 5, 2008, 12:45 am    Post subject: Re: What do people do with Breather Outputs With No Airbox?

Now you guys got me started.....thanks.....a good check valve for adding negitave pressure and the stock induction system ""combined"" really works wonderful............noticable improvement everywhere including plugs.....nailed it first time out of the shoot and that hardley ever happens.....

xsjohn
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kzxs
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PostPosted: December 5, 2008, 12:56 am    Post subject: Re: What do people do with Breather Outputs With No Airbox?

Now that I have read through this whole thread, now I'm am very interested in installing the check valve. I have added pods this summer and have acquired a slight leak- more like seeping. I will order this from through our parts department in the morning. Will be be a nice weekend to test it... about 54 degrees Saturday.
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XS919
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PostPosted: December 5, 2008, 1:21 am    Post subject: Re: What do people do with Breather Outputs With No Airbox?

Negative crank case pressure is good because it improves ring seal. That's one of the main power benifits. Rings are sealed against the cylinder walls by the combustion pressure getting in behind the ring and pushing it out against the cylinder walls. Any positive pressure inside the crank case works against this reducing the pressure and lessens the force pusing the rings into the cylinder walls.

It's been a common practice in drag race cars to install a mechanical crank driven vacume pump on the engine to create a strong negative pressure inside the crank case. The HP lost in driving it is more than made up by the HP gained from improved ring seal.

Cheers

Michael
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TeeCat
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PostPosted: December 5, 2008, 10:43 am    Post subject: Re: What do people do with Breather Outputs With No Airbox?

Guys, this is a great thread!

Quote::
Crankcase breather valves have a flap that takes very little pressure to open because its hinged and has a large service area...sprung cylindrical valves are both too slow and require too much pressure to open...

I am not in the US..so I was unable to check out the valves anyone's talking about..just recounting what I learntt...

Jake, no... I get what you're saying. I never did the "mouth test", but the Motormite/Help valves that 5twins and I (possibly others) are using has a sensitive flap, I believe, versus a stiff reed or a ball; that's why I think 5twins recommended this type. I don't think they're sprung. I suppose the only thing is that there's no real "eyeball test" to see if they're opening once installed.

One thing I remain a little concerned about is whether the fact that my valves and breathers are installed low, at the ends of the stock hoses, makes any difference in the valve's operation. There isn't much room up above that.
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Jake68
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PostPosted: December 5, 2008, 11:16 am    Post subject: Re: What do people do with Breather Outputs With No Airbox?

Thats good news T-Cat...sensitive flap sounds like a possible winner to me...

Probably as good as Mikes then...

It also occurs to me that combining them into one valve will give greater pressure on it to open properly..
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5twins
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PostPosted: December 5, 2008, 12:42 pm    Post subject: Re: What do people do with Breather Outputs With No Airbox?

I recommend anyone doing these mods get the new hose from Mike's. It's exactly like the original - thin walled and a smaller O.D. than any automotive hose you'll find. This allows the original protection spring to be used (it won't fit on the auto hose). You need that spring because the new hose is very soft and can kink shut if you bend it too much anywhere along it's routed path.

I bought the long 1 meter length because I wasn't sure how much I'd need. Turns out it took less than 6" per hose to get the valves exactly where I wanted them - sitting right over the tops of the pods. The shorter length w/ spring that Mike's sells would probably be enough to make 2 hoses.

Another benefit to the 2 short hoses is I no longer have to remove them to access my carb tops. They need only be pushed to the side to allow top and slide/diaphragm removal. Before with my 2-1 hose into a breather filter, I had to pull both hoses off the engine to get at the carb tops.
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PostPosted: December 5, 2008, 1:29 pm    Post subject: Re: What do people do with Breather Outputs With No Airbox?

Again my 2 cents on this………Using the stock air box intake induction system in conjunction with a "correctly designed" one way valve for this application will increase the vacuum forces working toward obtaining negative crankcase pressures…..especially at higher rpms where the valves won’t work as well due to the rapidity of the cycles… but I suppose some improvement is better than none…….

And just because one can hear the induction noises that everyone is familiar with when removing the stock air boxes and adding pod type filters doesn’t necessarily mean that the system is working more efficiently……when I take my modified air boxes completely off I can’t notice any performance gain…..just induction noise….

xsjohn
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Jake68
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PostPosted: December 5, 2008, 4:00 pm    Post subject: Re: What do people do with Breather Outputs With No Airbox?

Yep the hose from Mikes is a must...

I'm gonna have to get some..the automotive stuff thats of sufficient quality is way way too thick...thats why I got no room left in that area! Two thick walled pipes coming of the twin output breather uses up a hell of alot of space so much so that the installation of the two fuel filters I need is nye on impossible.
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PostPosted: December 20, 2008, 12:36 pm    Post subject: Re: What do people do with Breather Outputs With No Airbox?

For you guys who are using the breather valve now, is the water/condensation that normally breathes out of the breather tube still draining out?
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xsjohn
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PostPosted: December 20, 2008, 1:00 pm    Post subject: Re: What do people do with Breather Outputs With No Airbox?

"""water/condensation""

Lets it out but not back in......should even be better........valve I built sure seems to work great...right into the airbox as usual..helped the very bottom revs 15-1800 even more....makes the tall gears and lower compression even better...(again higher compresson works against the very low rpm's)......real curiser now....can ride for hours now without any of the old brain interuptions if you know what I mean.....I'm a perfectionist.....and there is nothing left to fix...knock on wood of course..... thanks again for banging the valve idea...

You could use only one outlet ...only really needs to be a 1/4" ID like the later ones.....or maybe that double outlet will press out and something could be bonded in the hole there...or a single 1/4" ID tube welded and the others ground off and filled..?.....water hose end or some kind of reducer tight fit and epoxied in...(just thinking)....dump the steel wool jammed in there too..?

Put mine in the line close to the head and then T'd the tubes off to the airbox using the stock setup .....don't see it....I can make more of these if people want.....bit time consuming though.......

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engine22
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PostPosted: May 1, 2009, 8:34 pm    Post subject: Re: What do people do with Breather Outputs With No Airbox?

Here is what I did, chrome breather with mount bracket from mikes with a T taking both breather hoses to where I have it mounted on the right side. Works good and fits right where the airbox was.
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PostPosted: May 1, 2009, 8:37 pm    Post subject: Re: What do people do with Breather Outputs With No Airbox?

Picture didnt upload, here it is.
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PostPosted: May 1, 2009, 8:51 pm    Post subject: Re: What do people do with Breather Outputs With No Airbox?

The brake check valve is a thin viton type seal, so it should hold up for a while. Where it normally sit's on the car's, it is subject to alot of unburned fuel vapor, but crankcase's also have the acid mixture, so a simple breath check now and again would be in order. They work great, though.
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PostPosted: December 13, 2009, 10:08 pm    Post subject: Re: What do people do with Breather Outputs With No Airbox?

Alright.... So are there any negative performance from just having the hose drop straight down and spew out on the chain? That's how mine was whenever I got it....
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