As silly as it sounds, I am having difficulty figuring out how the PCV valves work (have problems visualizing things at times). What I read stated that the default position of the valve is open and that intake vacuum serves to close it. Assuming the valve is a single circuit system, I would think that the amount it is open or closed is due to the pressure differential (intake pressure/vacuum on one side, crankcase on the other), which would work. On the other hand, if it's a two circuit set-up (which means that the opening mechanism is sealed and involves intake vacuum working against a spring only - the scond circuit being the flow-through from crankcase to intake manifold), then intake vacuum is the only factor determining the size of the opening (and this is NOT what is needed IMO).

As for the PAIR sucker mod, it makes sense but I remain concerned about the escaping and burning oil raising the temperature inside the pipe and ruining my $$$$ Akra pipe....

 

Other question about the PAIR mod, would this set-up cause the bike to backfire and pop like when the actual PAIR was in place?

 

Yes, would pop through exhaust. I dont think that it would ruin the exhaust, but I will let you do the experimentation on that. As for the operation of the:
http://www.autoshop101.com/forms/h63.pdf

 

Thanks Bill

 

No Problem. You got me in a modding mood. We are working on the 1980 SRX440 now, and waiting for ice to start laying down some passes. I ported the intakes this year, we balanced and welded the crank, balanced rotating assemblies, making adjustments to the MSD ignition system that we adapted to our sled, and etc etc. I can't wait to try and make this thing go. Next up, lube-rs for the Hyfax.

 

I remember drooling all over that sled when it came out. Good luck. FWIW, I jut picked up a sled yesterday (work for a sled magazine), an Arctic Cat TZ1 Turbo LXR. Not exactly my type of sled but with 177 hp and 120 lb-ft of torque, it's a goer nonetheless. Looking forward to getting out on our Ski-Doo GSX 800 SE (E-TEC)..... a luxury cruiser with lots of ***** and great handling too.... Still waiting for winter to arrive, however.......

 

Still looking for info on the working of the NAG valve and found this:

http://zaidantj.hiho.jp/ron/19ron/ron_19_04.pdf

Have a look at figure 4 on page 2. This is pretty well how I imagined it to be (a one-way valve which works off the difference between the crankcase and airbox pressure). Simple and straightforward. In essence, the weight of the floating piston is what sets the vacuum setting in the crankcase (instead of a spring).

 

I just placed an order for a device called a Krankvent (Motorcycle KrankVents). Supposed to work on the same principle as the NAG valve (only at about 1/4 of the cost). We'll see how it works.....

 

I pondered pcv for the VTR long ago and did nothing and waited until now to wade in here. On my "Baby Hawk" (NT650 Hawk Gt) I plugged the air box port and extended a hose from the rear valve cover breather port into a oil catch bottle & then to a CC breather filter located under the tail cowling. Seem to help top-end breathing. Years ago I dealt with CC breathing issues on my 1961 Matchless G80CS Cafe British single, and Harley Davidson has had issues with their CCB systems to this very day, which the "KrankVent" devices are meant to address. Let us know how it works.

Months ago when I was pondering this questionable issue on the VTR, I ran across the below links, which offer an even less expensive possible solution...

Bunn Breather

Bunn Breather Kits