900ml of oil max
This is a discussion on Blowing all oil out breather????? within the Chinese/Import Minis - General Discussion forums, part of the General Talk category; I finally got my piranha running good and now it's blowing all the oil out of the vent on the back of the motor. I ...
I finally got my piranha running good and now it's blowing all the oil out of the vent on the back of the motor. I know the obvious answer is that I have to much oil but I filled the oil to very bottom of the dipstick and it blew all oil out until I couldn't see any oil remaining. What could be causing this? My rear end of my bike is completely covered in oil even though I have a hose on the breather.
I had this same problem. First you need to put on a head breather. You can buy em or make it yourself for like $5 off the intake rocker cap.
The other times I saw this happen the rings were on their way out and I was getting blow-by, causing excess pressure in the crankcase.
I had same issue before.... make sure all crank case vents are clear and unobstructed, check oil level... if it still does it its time for a topend.
Well my top end only has an hour on it so I'll check the crank case vents and get a head breather. It's not the oil level because I went to change it when I got home and there was hardly any oil when I drained it.
you shouldnt NEED a head breather by any means... many many MANY people run bikes of all sizes without them.
I'm willing to try it I can't keep losing 90% of my oil
Do as you must bro... I'm just telling you if yourE blowing oil out the back of the engine a head breather isn't going to fix your problem lol. I'm willing to bet you just have too much oil in there. But what do I know...
I run a jialing engine, it blew oil like crazy out the crankcase vent when I went to a 146 kit. After I put a head breather on and it quit blowing oil.. but then again my crankcase vent was VERY small
You said your top end only has an hour on it, did you rebuild it yourself, or know who did? If the ring end gaps are not staggered correctly, combustion pressure can easily get into the crankcase.
There is alot more to it than just staggering the rings. I'd say bore size and finish could be the problem. The valve cover vent is a band aid that may help. The crankcase breather has a baffled chamber inside it and is the correct way to vent it. I have built many of these engines and seen alot of junk bore jobs. I have had at least 3 cylinders ruined due to improper bore and hone jobs.
Ride on the edge
Yea I too have built some 192s to stock 160s with V2 heads and without. I dont run a head breather on any of them. A head breather is going to blow MORE oil than the cankcase breather.. Something else is causing the problem. Does the line come out of the engine then make a bend and shoot at the ground in front of the rear tire. Or is it run up the frame to the back of the bike ending at the rear fender? I had a cracked LEFT crankcase and you couldnt see it when it was sitting still but the crack was near the output shaft so when you rode it hard it got oil all over he back of my frame and rear tire. I thought I was blowing it from the crankcase vent the intire time. I finally ran it to the back of the bike near the fender and on the same ride the crankcase finally broke and half of the tranny gears were hangeing out. Point is run the line up to the back of the bike near the fender. Make sure the oil you are seeing is comeing from the crankcase breather. IF it is then compression is getting into your crankcase halfs either around the piston OR your head gasket is blown between the cylinder and where the cam chain runs. IF compression come out of the head gasket there it will cause the crankcase to presurize. You know your bike and blowing oil JUST after a topend swap with only 1 hour and all the lines are kink free im going with head gasket.. Something changed when you replaced the topend. Did you replace the cylinder and piston as well.. Tell us what did.
Last edited by taz69; 03-09-2012 at 08:10 AM.
I'm no expert here, but I run a head breather that's basically integrated into the intake-valve tappet cover ( aren't they all? ) and I've put about an hour on my bike ( KLX 110, stock bore ) and it hasn't blown any oil, and it's actually pretty cool, if you put your ear to the hose you can hear the tappet, it's pretty neat, but that's besides the point. I'd say make sure there's no obstructions, as stated, and also make sure the ring gaps are correct, like others have said. That's my best guess as to what could be happening to cause a lot of pressure in the cases and make oil blow out I'd say.
Head breathers also suck air in... if you put your finger over it you will feel a light suction... hence the filter at the end