| Author | Message | ||
     Silas_clone |
I have been working on my carb/breather set up and getting great tips from BWer's, thanks! The XB/PVC conversions to replace the umbrella valve system in my 99 M2 sounds great, but could I not just splice an automotive PVC valve into my Crankcase vent hose somewhere? | ||
| Fullauto |
Try one of these one way fuel valves. Works a treat.   Got mine from a local auto parts store. | ||
| Buellistic |
How BIG is the car engine that it is supposed to be used on ??? IMHO a PVC valve meant to be used on a "BIG CI" V8 will not work very well on a 74 CI V-Twin ??? Less we forget about putting one inthe timing plug hole ??? Or maybe that is why they do not prove out on DYNO runs ??? (Message edited by buellistic on October 16, 2008) (Message edited by buellistic on October 16, 2008) | ||
| Natexlh1000 |
You guys are working too hard. There are already one-way umbrella valves built into the rocker boxes. If you run a straight hose out, you can feel that air is only coming out when the engine is running. Most of what comes out is water vapor with just a touch of oil mist. A common misconception is that if you route the hoses up and over the engine, it will condense and drain back into the engine. | ||
| Silas_clone |
Nate, I am good with umbrella valves, but if they s--t the bed, why not a regular PVC Lafayette, I gotta be mindful of that, but I understand that before the days of PVC, the crankcase was simply vented [not green, I suppose?] If the system is not working...? Full, you gotta a make and PN? | ||
| Buellistic |
Smokey Yunick understood the value of good PVC "VALVE/VALVES" to make his engines run better than anyone else's ... Remember the devil is in the details and just good enough does not cut it !!! That also applies to building long lasting engines and/or "PRODUCT IMPROVING" OEM engines ... | ||
| Jramsey |
Not trying to nitpick guys but its called a PCV valve. Positive Crankcase Ventilation. PVC valves are in the plastic plumbing section at your local hardware store. Next time you have the rocker boxes off use a chamfering tool and put a small chamfer on the umbrella hole seat this will pretty much eliminate sticky umbrella valves. | ||
| Silas_clone |
PCV, PVC...it's all ball bearings. But tell me more about what happens if the breather system is malfunctioning. | ||
| Buellistic |
The BEST example of what a PVC valve can do for your engine is to stop the CYLINDER GASKETS from weeping(timing plug PVC) ... That is one problem that my engine does not have ... What they really do is relive the pressure from the pumping effect of the pistons internally ... The way to help the drain down of the oil in the heads is to put oil line fittings in the heads at the lowest points of the valve spring pockets to quickly drain the oil out(this is one of the reasons for valve guide seals)to the bottom end ... | ||
| Silas_clone |
I guess what I would like to know is; are PCV valves an emissions necessity, or does you engine run as well by simply venting through a straight pipe into the atmosphere? | ||
| Charlies_s1 |
Well my understanding was it creates a slight vacuum in the crankcase and that in turn helps with oil leaks and also has been noted that on dyno testing that on Nortons they saw a increase in H.P. This may be due to the fact on those twins the cylinders move together. Chuck | ||
| Jos51700 |
A proper POSITIVE crankcase vent (In other words, a vent with a valve system) will give you power, in addition to reducing gasket and seal failure. CycleConnections Project "V" saw a (IIRC) double digit horsepower gain by adding a HUGE additional case vent. (Granted, it was a Vrod making 200 plus ponies) This is why I despise adding the XB rockers to a tube-frame. It eliminates the ENTIRE valve system! The valving creates a (Light) vacuum in the crankcase, but the tube-frames don't have the reed-valve in between the crankcase and the cam compartment. Don't forget, crankcase pressure is the WHOLE reason a two-stroke works! | ||
| Jos51700 |
"This may be due to the fact on those twins the cylinders move together" The pistons move (essentially) in unison on all Buells, as well. (Except Blasts) | ||
| Buellistic |
That is whay Bill Werner was able to get 4 more HP out of the XR's ... The engine was then referred to as a "TWINGLE" ... This was first done by NORTON Tuners, then by the HONDA Tuners ... Then Werner did it which worked quite well on HALF MILE DIRT TRACKS ... | ||
| Charlies_s1 |
But they are not at TDC at the same time, So they tend to offset the pressure somewhat, Chuck. | ||
| Ducxl |
But tell me more about what happens if the breather system is malfunctioning. a friend with an old Knucklehead capped his off inadvertently. So much pressure built up he ruined head/base/pushrod gaskets.He had oil weeping out of everywhere. They used to vent into the primary. The thinking was,with a dry sump oil system there was very little crankcase volume.Venting to the primary gave more volume.Venting to the airbox NOW does the same,and additionally burns the vapor/spooge that exits the crankcase. | ||
| Jos51700 |
They used to vent on to the chain, as a chain oiler! | ||
| Buellistic |
Venting into the intake pollute's the intake charge !!! Total loss chain oiler means a HOG always marked it's spot and you, if you rode behind one !!! | ||
| Bluzm2 |
Jos, The PCV valve on the top of the XB rockers IS a one way valve. It serves the same purpose as the umbrella valve on a stock 3 piece unit only better because it's out of the "oil path". Far less spooge. If you feel the output of a XB setup and a stock setup they are the same. | ||
| Jos51700 |
"The PCV valve on the top of the XB rockers IS a one way valve" That is incorrect. There is NO valving in the rocker breather (It's not a PCV valve). The ONLY valving on an XB motor is the reedvalve in the crankcase, between the flywheel compartment and the cam compartment. Cut one open if you doubt me, there's nothing but baffling and nylon stuffing inside, and it contains NO method of allowing air flow one way, and restricting it the other way. If you don't feel like cutting one open, try testing the "V" (for "valve") in "PCV"-blow through one, and then turn it around and blow through it the other way! A "good" PCV will not allow you blow through it both ways, and in fact, that's how you test a PCV from a car. If you measure the crankcase pressure on an XB, versus a XL motor with XB rocker conversion, you'll see a difference! | ||
| Fullauto |
Sorry I've been away for a few days. I first put one of these one way FUEL valves on my Norton. Instant disappearance of an annoying oil leak from my tacho drive and more power. Noticeably so. Basically, because your motor acts as a big air pump, pumping air out of your breather on the downstroke and sucking it back in on the upstroke it takes power to do this. By pushing this air in the crankcase out of the breather and using the one way valve to stop it being sucked back in, you basically create a vacuum within the crankcases, stopping this pressure from pushing oil out of gasket surfaces etc., thereby reducing or eliminating oil leaks and giving the engine more power by reducing it's workload. I thought it worked so well on the Norton that I went out and bought one for the X1. Again, noticeably more power. Works for me. Silas, the only info I have is what's on the box. There is a part number shown and the maker is Redat of Italy. It was sold to me as a one way fuel valve. I was wondering if this was the reason why early Jap twins didn't leak oil. They had 180 degree cranks instead of the traditional 360 degree cranks of the Brit bikes, hence, their crankcase volume didn't change, therefore, no pressure buildup. Regarding venting to atmosphere, once you have a vacuum in the crankcase, their is no more pumping of crap to the atmosphere. This takes about 8 seconds on the Norton and has resulted in less spooge in the catch cans of both my bikes. Interesting stuff. | ||
| Jos51700 |
If you look at the late-model Jap fours, they've cut windows in between the cylinders to allow a more direct flow path of air between the rising and falling pistons.  Neat stuff! | ||
| Buellistic |
Looks like the anti-freeze cooling jacket to me ??? | ||
| Jos51700 |
Not between the cylinders. The exterior hole I highlighted is where they bore all they way through the block. Here's another tidbit: http://www.mcnews.com.au/newbikecatalogue/2003/Suz uki/GSXR1000/GSXR_1000_2003_Page1.htm | ||
| Jos51700 |
After a bit a research, I must issue an apology to BluzM2. The '03 XB9R Buell Service Manual DOES indeed refer to the rocker box "turret's" (aka breathers, as I called them in this thread) as "PCV valves". Now, I was wrong to tell him he (I am assuming he's a he, anyway. This is the 'net, after all) was incorrect. Personally, I have cut these breathers/PCV valves open, and they contain no valving mechanism to my knowledge. Since they allow air flow in both directions, to me, that makes them NOT valves, but breathers. However Buell does refer to them as such, and so I must admit that it is highly likely that they are as such, and again, I wish to apologize to BluzM2, and anyone else whom I erroneously "corrected". | ||
| Silas_clone |
We were in Tennessee, so I could not respond. Since PCV valves on XB's are not one way valves I am starting to hone in on what I had hoped, that is; the umbrella valves or any other "one way" valve system is not as crucial as making sure that the crankcase pressure [built up by both big pistons falling at once] is vented to the atmosphere. I do agree that any "blocked" umbrella valve will be a deficit to performance and will probably be the cause of leaks. Whether or not a "one way" valve is an improvement on performance seems to be the question now. I do know that in the HD UL/FL [knucklehead] repair manual, riders are encouraged to "snap the throttle shut" once in a while on sustained hi speed runs to create a vacuum which is intended to draw lubrication up into the cylinders. Also, BIG TWINS from the 40's [at least UL flatheads] had their primary chain oilers fed DIRECTLY from the oil FEED pump, not from a breather system. I ran an open primary [it looked cool and dangerous] so I had my oiler plugged with no ill effects. I believe that some examples of scavenger side pumps also had a bleed screw, possibly for the rear chain? | ||
| Fullauto |
Matt Rambow of Colorado Norton Works tells me that the power gains from using one way valves in breathers can indeed be measured on the dyno and he has indeed, done so. Logically, with a one way valve, you are not drawing air back into the motor to be pushed back out to atmosphere with each downward push of the pistons. You can only push out the volume of air which is in the crankcases when you start up. Therefore, one would think that there would be less pollution venting to the atmosphere. | ||
| Buellistic |
Jos51700: "THANKS" as "i" now see what you are indicating ... Will check this out as a "PRODUCT IMPROVEMENT" my 1997 S3T if if ever wears out anytime soon ... | ||
| Jos51700 |
"the umbrella valves or any other "one way" valve system is not as crucial as making sure that the crankcase pressure [built up by both big pistons falling at once] is vented to the atmosphere." But it is. That's why XB's use a reed valve in the crankcase-to generate a difference in pressure. | ||
| Jos51700 |
"I do know that in the HD UL/FL [knucklehead] repair manual, riders are encouraged to "snap the throttle shut" once in a while on sustained hi speed runs to create a vacuum which is intended to draw lubrication up into the cylinders. " This had less to do with crankcase pressure systems, and more to do with very poor ringseal. The vacuum in the intake tract (and then above the pistons) when the throttle was chopped, pulled oil up into the rings, whereas normal high-speed operation created high-speed blowby to the point that oil was forced from between the piston skirt and cylinder wall. |
