PCV Valve

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olympus

olympus

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I read with interest the numerous threads relating to crankcase modifications & the fitting of a PCV valve
looking at 3 and I know there are more
JS Motorsport
Holland Norton Works
CNW
Across all three there is a very significant cost difference. I appreciate its horses for courses and one is "off the shelf", but I would appreciate some feed back on the above units ...Good/bad /indifferent to help me establish the best unit to purchase.

Thank you
 
Not sure what you’ll gain here... everyone who has any of the above (and / or others) is gonna tell you it’s the greatest invention since tyres...

You’ll be none the wiser!

FWIW, my advice is to read all the research and testing and draw your own conclusions.

BTW, you missed the Comnoz screw in sump plug version off of your list.
That’s what I’ve got, and seriously, it’s the best invention since tyres...
 
Brake booster check valve = ghetto mod = works

XS650 = works

Comstock/CNW = works great, plus wet sump recovery
 
All three are a simple reed valve, the HNW (Yamaha XS650 ?) and JSM units are mounted above the crankshaft centreline, the Jim Comstock versions are a different kettle of fish especially the version that fits into the sump plug location. (No good on a 72 model I guess so it gets its own version to fit the rear of the engine case)

I bought two of the sump versions because I think they are the better idea, I could have machined my own manually (xxxxx hours) but why bother, they are CNC machined and you just fit them.

One thing you do need to watch is some 850 cases have more material so that sump version will not fit directly.
I simply machined a relief with a ball nose cutter so the pick up tube could be left as is (not cut down)

PCV Valve


PCV Valve


PCV Valve
 
I would add the sump version is a lot more 'high tech as it has the tube pick up to the reed valve but also has the needed screened pick up for the oil return to the scavenge side of the oil pump.
The other two are in ideal circumstances pumping air only, the sump version is able to return oil (wet sump) to the oil tank and oil heavy vapour under running conditions. ???
 
Fast Eddie said:
BTW, you missed the Comnoz screw in sump plug version off of your list.
That’s what I’ve got, and seriously, it’s the best invention since tyres...
Click to expand...

Looked on his website, but cannot find it. Perhaps I've just missed it but wonder if it's no longer for sale.
 
I would recommend Comnoz's unit after reading a ton of threads here. But fwiw Mikes XS650 has the low dollar Yamaha units available once again. He was out of stock for a very long time until recently.
 
I'd get the Comstock/CNW one specifically because of all the testing Comnoz does to verify. Any claims made from Jim as to what any of his products do are from either running them on his own bike for lots of miles, testing in the lab or both. I don't know if Jim still sells these himself or whether all purchases need to go through CNW. There have been lots of DYI copies made, there are other products out there that will provide similar results, but you might as well support the effort that goes into some of this stuff. We are all a better community for it.
 
yamaha YBR 125 EGR valve, very often got loads of them on ebay cheap as chips and works very well indeed
 
L.A.B. said:
1972 crankcase so there's no (large) sump plug.
Click to expand...


No, but yours in the one the CNW one fits right on to. As it does to Maney cases, which I have.....it’s the best invention since tyres.....

Sump clearing is one of the best features.
 
I've put the Ghetto brake check valve on my 850 breather hose...$10...direct 10 minute fit, locally available...oils leaks abated immediately. If it survives past a few 1000 miles, I'll consider it a winner in this contest.

BTW, what is a decent solution for a 750 engine without the timing case breather hose fitment? Met a fellow rider at the bike show yesterday that has 3 750's and wants to try a PCV.
 
Time Warp, Jim modified his later ones so that the stalk could rotate and miss some of the castings inside the case.
I had one of his early ones and found it bound up, he sent me a modified version and I sent the initial one onto a guy in QLD.
I have three of them in use, excellent product and works even better with specific timing chest holes plugged.
The one on my road bike has taken a bit of grit blasting on the leading edge due to the odd gravel road excursion plus from general grit on the tar seal roads
Regards Mike
 
Mike, the pick up tubes on both of the units I have can be moved from straight up and down but as per the first picture even canted over as far as it would go it was not going to fit and I did not want to shorten the tube itself.
I think I had read here somewhere (Access Norton) some of the 850 cases are like mine and there might be some contact, I wasn't worried, setting the case up on the angle plate was no problem and then a bit of 'whittling.
I swapped a couple of PM's with Jim re what I was going to do (and if the tube could be cut a little if no option) but there was enough thickness in the case to cut a relief without cutting it (the tube).
The height of the tube is important I think with that unit also having the mini sump for the scavenge return.
A great product.
 
Mine is almost identical to the Mike's XS valve, but has less plumbing.

PCV Valve
 
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