I'm running a return to the sump from an oil / air seperator on the crankcase breather on my R1, there is a well known issue on these engines (2005 onwards) where they can actually pump quite a bit of oil out when held at high revs (1/2 a litre on a run at curborough!)
I'm trying to figure out what size pipe fittings to use, the crankcase breather is about 11mm ID but thats obviously coming out under pressure, the return will not be under pressure just gravity so i'm thinking I maybe need to go bigger.

Anyone got a Jic fitting to hand to confirm my findings that the ID of the fitting is 1/16" x the dash size, I've looked at various catalogues and I'm not convinced the ID they show isn't reffering to the ID of the hose the fitting uses rather than the ID of the fitting itself which is obviously smaller.

Hope this makes sense, any assistance / advice gratefully received

I have just added this to my engine, used JIC -8 back to the sump.

This is the same an engine tuner I know does.

Jic fittings sizes refer to the OD of the thread in 1/16ths of an inch.

So JIC8 (or -8 or AN8 all the same!) is 8/16" or 1/2" diameter on the threads.

David

ko_racer, is yours an R1?

If -8's OD is 1/2" whats the ID of the fitting, 3/8" or less? Can anyone measure tell me how to work it out.

My friend got some bits from Demon thieves last week, we can't find the invoice and the fittings are at the garage not with me so I don't know what size the fittings are but the ID is about 10mm or 3/8"

I've got the 5VY 04-06 R1

I/D of -8 Hose should be 7/16"

Linky

thats great thanks

The AN "dash" sizes DO refer to the size of the hose bore (in 1/16ths inch) that the fittings are designed for, nowt to do with the thread.

JIC threads are generally accepted to be common for each "dash" size, and -6 would be 9/16 x 18 tpi -8 would be 3/4 x 16 tpi, -10 would be 7/8 x 14 tpi and -12 1 1/16 x 12 tpi

these are all the diameter over the male threaded part of the fitting

The bore of the fitting is much less that the hose pipe. You can usefully bore out the fittings to increase the flow on a return pipe which is subject to less pressure. As the area is proportional to the diameter squared the gain is significant - I gained 20% on my dry sump pipes.

I also bored out the pressure pipes but not to the same extent more of a streamlining to take out the ridges.

No problems so far.

v8kid, that was my recollection and the reason for the post but the question got lost somewhere, possibly due to the way I worded it.
It seems obvious to me but surely when designing a pipe run it should be based on the smallest ID i.e. teh ID of the actual fitting as thats where the restriction will be?

On mine I have the home-made air/oil separator which has 12mm pipe at the bottom which fits onto the top of the external sight-glass which is then connected back to the sump using some JIC -6 hose. Seems to work fine so far.

Brommers, you have U2U