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Old 10-18-2012, 11:55 PM
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Default Blow-by question

I posted this in the engine... forum, but didn't get any answers...1995 FLHR

This is a Sputhe 104 motor, now going .032 over. Already did 10 and 20 over. I run Branch-Okeefe heads, and a Crane Hi Roller 304-2 cam. Compression is estimated at 10.5:1 with 78cc heads. Dyna 2000i ignition, and Rhienhart pipes. Mikuni 45. 110hp 117torque, dyno by John Golden, 'The Dyno Guy'

"I have had lots of blow-l by on my stroker motor (4.625 stroke) and I have found several probems with the motor that I am fixing now; needs new crank pin, rods, and a bore out. The cylinders were badly scored, which I imagine helped contribute to the blow-by. I also use a S&S reed valve breather, which seems to work fine.
My question is can I route the breather tubes off the heads and back into the oil FILLER housing. This housing has a plug in it, and I thought it would be great if the mess just wound up back where it came from. Or would adding a little pressure to the oil tank cause problems? I don't think the pressure is that great. The bike is a 1995 road king.
Any thoughts on this? I really don't want to use panty liners in my carb cover."
 
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Old 10-19-2012, 08:36 AM
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I think that would be A Bad Idea. You need a vent somewhere and the oil tank is not vented. I think you would blow the dip stick up and out, which would be interesting, but not what you want. I think a better idea would be to put a catch can somewhere, like under the seat if you can.
 
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Old 10-20-2012, 03:36 PM
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Usually a big bore tube out over the rear mudguard is the way to go, the longer the tube, the less mess will make it to the end.....used to fit a catch can on old Brit bikes back in the day as some of them can pump oily crap a long way when you give them some throttle.
 
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Old 10-20-2012, 03:44 PM
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Originally Posted by Dr.Hess
You need a vent somewhere and the oil tank is not vented.

The tank is vented to the cases, but it would no longer be if you ran the vent to the tank...you need a catch can...

here ya go:http://www.ebay.com/sch/sis.html?_nk...9#ht_693wt_719
 
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Old 10-21-2012, 10:58 AM
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Unless you're running a different setup, the oil 'tank' is an 'oil pan'. The MoCo changed to the pan design in 1993 on the E-Glides, where the oil pan is under the transmission case. I'd have to look at the diagram to see if the pan is vented, but I don't think it is vented independent of the oil system. I believe it gets its venting via the heads. Soooo....

If the issue is too much oil puking out the heads via the venting holes, I would go with the catch can. Which is probably what I'll be installing on my EVO, as the heads are venting a bit more oil mist than the carb can digest.
 
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Old 10-21-2012, 11:42 AM
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Yeah, the oil tank/pan is under the transmission. I know that there is a vent tube from the motor case to the oil pan, as shown in the service manual. The motor was venting normally for years, then became progressively worse. I ran a breather hose all the way to the center of the rear fender, extending about 1/2 inch, so all the blow-by would get blown away, so I thought. I didn't take the back pressure of the moving bike into account, and still ended up with a mess, and when I parked, the rear fender dripped oil. Any way, when I heard it knocking, I tore it down, and found a bad rod/crank pin. So...I got it in for new rods, pin, bearings, bore out, and freshen up heads. So it will be pretty much all new when I am done. Cam and lifters are good, so they will remain. I am looking at about 5~6 weeks before I get it back together. Bennett Performance doing the crank, and bore job, Branch doing the heads, Pistons coming from Axtel on order. Nothing just off the shelf, except gaskets. I hate waiting, and I have motor parts spread neatly, and itemized over half my garage. I will do the assembly.
I always kind of known I needed a puke can, and have had ideas for a custom one. Just wanted to throw other ideas out. Now that I have the time, maybe I will make one.
Thanks for the comments guys. I will post again when I have it broke in, and have a few miles on it. I live in So. Cal, so it is always riding weather.
Be safe
Steve
 
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