Foamy oil in crankcase breather tube

B

bigbutterbean

Active Member
I have a 98cc Lifan. Like many others, I do not want the crankcase breather tube connected to the carb, so I ran it down (removed the one that was there and installed a length of 3/16th fuel line) and zip-tied it to my engine mount. I noticed the other day when I put my finger on the end of the tube (engine was off) that there was foamy oil in the end of it. I squeezed it and a few more drops of foamy oil came out. So I'm just wondering, is this normal? Been riding this bike for almost a month now, and the engine runs just fine and pulls pretty nicely.
 
Yes that's pretty common... My predator does that same thing, except it all collects at my catch can, keeps the bike cleaner

you can make a catch out of almost any small container.
 
I'm glad to know its normal. I don't have a lot of room to install a catch can, so Ithink when I get a chance I'll install a filter on the end of the breather tube.
 
I'm pretty sure there is a complicated reason why it happens, i imagine it has something to do with the oil releasing something as it heats up.
 
For now you could tie the breather up to the seat post up under the seat. Zip tie a bit of cloth to the end for a makeshift filter. Making sure that the engine gets up to operating temperature will ensure that the condensation boils off. And yes, yes its quite normal.
 
condensation will always be present,as one of burning gasoline's byproducts is water.for every gallon of gas burned,approx one gallon of water is produced.i actually read it somewhere,long before the internet was a glimmer in someone's eye.
something to do with stoichiometric ratios and such.

the normal occuring blow-by will carry oil and water out the breather.a fine screen would be preferred over a paper filter,or a tube with steel wool lightly packed in it.
 
tooljunkie said:
condensation will always be present,as one of burning gasoline's byproducts is water.for every gallon of gas burned,approx one gallon of water is produced.i actually read it somewhere,long before the internet was a glimmer in someone's eye.
something to do with stoichiometric ratios and such.

the normal occuring blow-by will carry oil and water out the breather.a fine screen would be preferred over a paper filter,or a tube with steel wool lightly packed in it.
Click to expand...

I was thinking an ht stock in-tank filter screen would work best, if I can get my hands on one. I'll look around a few places.
 
Actually, I just realized that a tractor fuel filter would also work just fine, and I can pick one up on Friday after I get paid. I'm using a tractor fuel filter on my fuel line to my carb, and it works just fine.
 
I just hooked the breather tube back to the pcv inlet on the carb and took her for a spin, and she seemed to run a lot smoother. It was a short ride at 1 am lol, so hard to say for sure, but I'll definitely know after I get to work in the morning.
 
at 1am. women look better, food and drink taste better,you are faster and stronger and of course your bike runs better. i think it has something to do with earth spinning faster at the begining of the day.
 
Lol Dennis. After driving to work and back today, I don't think the bike runs any different, but hopefully the positive crankcase ventilation will improve my gas mileage. I'm not getting terrible mileage, but I don't think I'm getting quite as good mileage as I was getting on my 2 stroke. I've had this bike for about a month now, and mostly driving back and forth to work ( 6 miles a day round trip), I've put about $8 in my tank so far. I would like to not have to put more than $6/mo. in it. We'll see over the next few days if it improves at all or not.
 
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