Hayabusa breather question

wdonovan
Registered User
Joined: 20 Sep 2016, 15:01

10 Apr 2017, 17:32 #1

02 Hayabusa (from ser #). Injected. On the rear of the crankcase, over the gearbox is a rectangular cast box with a fitting on top for a rubber hose. Presumably this is a crankcase breather and my guess is, in the stock config it's routed into the airbox.

My engine has been converted to dry sump. This nipple was fitted by previous owner with a paper element filter / breather. First day on track with the car, oil vapor was blown out of the element enough to foul the engine compartment floor.

What is commonly done with this breather nipple when using a dry sump? Vent to tank? Vent to puke can? Block it off?
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924RACR
Registered User
Joined: 14 Oct 2008, 18:59

10 Apr 2017, 18:47 #2

Not a 'Busa, but on my (08) 1000 (also dry-sumped) we ran the identical breather up to an oil-air separator (made our own), which is actually located above the oil tank. Which drains back down into the oil tank - no more filling up the oil overflow every other session, now it's maintenance-free.

Sorry, no handy pics, but I will note that we didn't find an inexpensive separator pre-made; got an inexpensive tuner breather catch can, about 6" tall by 2.5" OD, designed to be emptied manually, and then converted it over to our needs. Ended up using little of the original design except the outside can and the mounting.

Inside of the can, the inlet goes into a tube that drops almost to the bottom of the can. Below this is the return fitting to the oil tank. A separate fitting on the top, without a dip tube, vents the gases to the breather/overflow bottle. The oil/air mixture goes all the way to the bottom of the tank, then has to make a 180 and go back up vertically 6" to have even a chance to make it to the overflow (so it doesn't).

I should note all the plumbing is 1/2" ID (same as the nipple on the engine).

My engine bay floor stays a lot cleaner now (used to blow out of the tank a bit, and quickly fill the overflow as mentioned).

Hope that helps...
Vaughan Scott


www.vaughanscott.com

#25 P2 Hidari Firefly
#77 ITB 924 - wife's racecar now
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farrout
Registered User
Joined: 22 Nov 2005, 22:26

10 Apr 2017, 19:01 #3

Pretty good discussion on this topic over on ApexSpeed.  http://www.apexspeed.com/forums/showthread.php?t=77670




My built 05 GSXR with a dry sump had that particular port plumbed into the dry sump tank.  It also became a "closed" system unless I overfilled the dry sump tank which them would puke the excess.
Craig Farr
2006 Stohr WF1 P2
Sanibel, FL
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wdonovan
Registered User
Joined: 20 Sep 2016, 15:01

11 Apr 2017, 15:52 #4

Thanks both. Guess I'm off to the Apex forum to digest as much as I can. I think a sensible place for me to start is to put a vac/pres gauge on the nipple and maybe even a balloon to see how much vapor I actually have to deal with. It would be nice if I could get away without building a separator but I will do what the car makes me do.
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wdonovan
Registered User
Joined: 20 Sep 2016, 15:01

11 Apr 2017, 17:58 #5

After reading the Apex thread, I hope to be able to do exactly what Craig did. I think there is only one return port on my dry sump tank but I am a few miles from my friend Stef who builds these tanks. I'll have him weld another port, probably -8AN, then just hose clamp a 1/2" hose to the existing engine vent nipple. I'm still going to put a gauge then a balloon on it to see how much air and oil comes out.
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wdonovan
Registered User
Joined: 20 Sep 2016, 15:01

10 May 2017, 12:51 #6

Update: I threw away the breather and ran a hose to an existing and unoccupied return bung near the tank top (didn't know it was there because it was hidden from view). No more oil on the belly pan so the universe is great again. Thanks for the suggestions here, guys.
Oh, and an intersting (to me at least) point. I did put a balloon on the breather port and started the engine. There was not enough pressure to inflate the balloon so I removed it and what I found was that under some RPMs very little came out of the breather but at idle (when the scavange pump was barely turning, there was a definite puffing out of the port.
Last edited by wdonovan on 10 May 2017, 12:54, edited 1 time in total.
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ted arken
Registered User
Joined: 03 Mar 2001, 04:26

13 May 2017, 04:01 #7

Yes the crank breather should be plumbed to the dry sump tank.  We ran dry sump kawasaki zx10 motors for years that way.  Make sure that the dry sump tank is vented well.
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