I'd like to send the crankcase mist somewhere other than the combustion chamber on my R100 monolever, but I don't want to install a catch can as the end device, not even one with a filter. And I won't be able to ride at the track if I vent it to atmosphere. Ideally I'd like to get it back into the system in a way that uses a vacuum, similar to the stock setup, for positive ventilation. What if I use the ports on the heads and the pulse air system tubing, sans the airbox valves? The reed breather is in effect a check valve that will prevent backflow, so I'm thinking if I can run the tube from it onto a tee, then into the pulse air system lines I can send it to the exhaust system.
My concern would be the high pressure pulses in the exhaust.The reed valve, as you say, an anti backflow device, but if a pressure pulse from the exhaust arrives as the reed valve is trying to open it will inhibit crankcase ventilation, not enhance it. Are you planning on a full on race bike or just the occasional track day?
You make a good point. Vacuum from the carb take-offs opens the air valves under acceleration and they close under deceleration. I suppose crankcase pressure through the breather doesn't work in this on -and-off fashion, does it. This is an occasional track bike but I run it pretty strenuously on the road.
KZ four-cylinder machines of the eighties delivered crankcase vapors to reed-valves opening to exhaust port. Reed-valve & passages were part of the cylinder head. A true "sucker valve" is plumbed as a ninety-degree bend in exhaust, with its open-end facing downstream. http://www.eurospares.com/sucker.htm
You could think of installing a more effective oil separator.The stock system imho has a poor performance.I have seen on other bikes and thus installed one of an early BMW R1100RS.Without a diode board and without the ignition can it can be installed under the generator cover.Feedback of the separated oil into the case, air could go into the intake system.But could be located anywhere.
If you can get your rings to seal really well, nearly nothing but air comes out of crankcase vent, which would make a catch can a mere formality. Good ring sealing gives more power, too. These engines do emit a lot of moisture when ambient temperatures are low, as all that aluminum is heated, but that shouldn't be a problem in racing.
That is a thought provoking thread. I spoke with guru Craig Hanson with Hanson Racing Technologies a few weeks back and he described the same system, using the AV13 check valve. I would wager that he is the Craig mentioned in the thread.
Does anyone here know or have an educated guess what the pressure is from the crankcase ventilation tube?
因为我决定只是发泄气氛se it was simple and turns out I'm not violating any rules at the track. With a Siebenrock oil pan spacer installed and running the normal oil quantity, there is very little oil settling in the can, even after extended runs in the upper rev range.
Thanks guys. Means a lot receiving feedback from PJ, RGregor and BMWrench, three guys who I have learned a great deal from over the past couple of years. My original intent was to build a cafe bike, but as form followed function, it became quite a track-worthy machine with nice power, great brakes and surprisingly good suspension. Now I don't like calling it a cafe because the term doesn't fit. I think you all have seen it before. Here it is in its current state:
The mirrors sort of work. They are a little narrow. I designed a cantilevered subframe and had a friend weld it. It took a lot of measuring and a few mock-ups to get the angles and ergonomics right.
From the looks I'd say this bike is a pleasure to ride.Which many of the cafe racers I've seen are not ......
