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Oil coming out of air filter area

2201 Views 6 Replies 4 Participants Last post by  Scott S
I recently started noticing small oil puddles under my engine after riding. I traced the "leak" back to my air filter area (the crankcase exhaust tube?). After doing some research, it appears that "blow-by" can cause this to happen. My bike has 20K miles on it, and it started leaking last fall after I had an 18K mile service performed by a Kawasaki dealer. During the service, they adjusted the valves and, of course, replaced the oil. Has anyone had experience with blow-by, and would changing the oil or adjusting the valves cause this to happen for some reason?

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Oil in the air filter

Scott S
I hate to think a bike dealer might be at fault and I dont like to accuse anyone of the wrong thing but it is very possible that the valve adjustment came out wrong. First the oil in the air intake tells me that an intake valve might just be a little too tight and allowing combustion to slightly blow back into the air cleaner, thus contaminating the filter. The lack of power is also an indication of tight valves. When you get into higher rpms the valve timing is changed due to rpms and valve overlap. the fact that you noticed a lack of power after you had it serviced and after the valves were adjusted could be the combination that could tell you the story. Again, I hate to blame anyone for anything but I couldnt pass up this coincidence. I dont know what kind of bike you have so I cant say any more. I own an 02 800 classic. It has solid lifters. Some newer and larger bikes have hydraulic lifters of which never need adjusting. Adjusting solid lifters requires the use of different thickness shims to adjust the valves with. There are no adjusting screws. It is sort of an intricate operation. Bring it back to the dealer or whoever did the service. tell him of the combination of the oil in the air filter and the lack of power since you had the work done. I dont think its blow by unless the first guy never changed the oil and thats not likely. Along with blowby comes smoke out the tailpipe and out of the crankcase breather or any tube comming out of the crankcase especially the little bottle under the bike that catches blow by oil. It just might be a very slightly tight valve.
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