Positive Crankcase Ventilation valve on Ariel single

[Vincent.vanGinneke]

Here some pics of the Yamaha PCV valve that I fitted onto my Ariel single.
The whole set up fits without having to make irreversable changes to the enginecases.
Note that the crankcase venthole is only on later model singles (I think after '53 -?)

exploded view of stainless bits that hold the valve

Crankcase + timingside vents connect

Position of the valve behind the oil tank

view of the set up

Text from website where the Yamaha reed valve is for sale :
Reed type Positive crankcase ventilation Valve. Valve hooks to engine top breather vent and allows expelled air out but reed prevents air re-entering quickly so a very small vacuum is created in the crankcase. A small power increase has been noted during dyno tests (most notable on pre 77 engines) and the crankcase vacuum helps prevent crankcase pressure from pushing oil past oil seals and case joints.[/i]
http://www.mikesxs.net/product/15-0677.html

[adrie.degraaff]

Hi Vincent, you're working very nice and tidy.

Don't use the felt ring behind the magneto, Fred B has had the vilt trough his engine (vacuum, sucking in!!!) , it must be rubber.

[Keith.owen]

Vincent,
Wasn't it you who had posted on this previously?

I bought some of these (rather more expensive than the uS$18 each, by the time I'd payed for the postage and customs fees).

I thank you for the detailed info provide on the install - I will take note!!

Keith

[keith.mettam]

Not sure how effective this will be without a seal on the magneto shaft as well. Also the drive side mainshaft has no seal on most Ariel singles so surely any potential internal vacuum will at best be minimal ? Your comments please !
Regards,
Keith.

[Vincent.vanGinneke]

Gents,
Proof of the pudding is in the eating, patience please.
I would not classify the magneto as a 'opening'
On my HS there is a large rubber seal on the mainshaft.
Keith, could you not buy them at your local Yam pusher? and yes it was me, somewhere in the topic SpAriel.
Adrie, thanks for the tip! I'll take care of that.

[Vincent.vanGinneke]

Forgot to add that where the brass pillar goes in I tapped a thread in there.
Originally the PCV comes with a pressed in tube in that hole.
A certain size BSP tap fitted (forgot the size and I wont dismantle it to have a look...)

[david.anderson]

Vincent
Neat mounting and similar to mine. A couple of points to be noted though.
The pcv valve should be mounted as close to the crankcase as possible, preferably directly attached to the crankcase, for optimum effect. (but my mounting is similar to maintain original looks) As the length of the connecting tube increases, the vacuum is eliminated, but crankcase pressure is still considerably less than would otherwise be experienced.
I eliminate/plug the timing cover breather when there is a crankcase breather.
The crankcase breather can push out a bit of oil so I exit the pcv valve with a rise in the hose, then take the hose down to a fitting on the chainguard to use it as a rear chain oiler.
The timing cover breather is not as effective as a direct crankcase mount, due to the passage of the air through 2 chambers after leaving the crankcase. On my pre crankcase breather singles I remove the ball from the elbow and mount the pcv valve off the end of the breather pipe.
I use the rubber magneto sealing washer and seal either side with a thin bead of silicone. I also use the HS HT crankcase main bearing seal that is available through singles spares.
The end result is a bike that does not leak oil, although special care must be taken with the sump plate.
David

[Vincent.vanGinneke]

Hello David, thanks for your comments! yes I also 'wondered' if the tubes where not to long.
As you write that the timing side vent is not really needed I could do away with some lenght there and mount the PCV somewhere under / besides the battery or even closer.
Oh bugger, just made myself a nice stainless holder for it that wont fit anywhere else............
I also was 'worried' about the different lenghts from timingside to 'Y' junction versus lenght from crankcase to 'Y' joint, but that could be academic....
+ the fact that the bit from the timing was pointing down a bit in the first 5 inches, again Oh bugger!!
Anyway, I just took the mag off to change the seal so all is apart at the moment.
But perhaps I first try it all out............

[adrie.degraaff]

The timing cover breather is not as effective as a direct crankcase mount,

I would also make it direct on the crankcase and than connect to the primairy, I even did this on my tricycle.., see the pictures.

The original HS primairy seal dus the same thing, letting fume in the primairy and closing when vacuum occurs.

[Keith.owen]

HI,
As a matter of curiosity, has anyone considered blocking off the crank case and timing cover breathers and then venting from a rocker box (perhaps the tappet cover)? There should be a fairly unimpeded air flow up the rocker tube, or perhaps this and the crank case.

I don't know what copyright law says but I have a very interesting article on breathing in an old special edition Classic bike magazine dating from about 1980 something. If no-one thinks I'll get sued I could perhaps scan it and get John to put it on the club website?

Anyway, the writer of this article is of the view that if you can breathe at a high point there is less likelihood of ejecting oil.

I am very interested in this subject, because having nearly finished my VH which is true to it's age, I'm building an NH which will be modernised.

I also intend to get more oil onto the cam (there have been articles on this as well).

Keith