Still blowing oil after several attemps to fix???

[mstngmatt]

This bike has been blowing out the breather into the airbox for a long time now. New piston and rings didn't solve the issue. New cylinder along with piston and rings. Oil is not overfull, and I've used synthetic and conventional oils. Didn't make much difference. Any help??

[Honda_Matt]

It sounds like the oil is sitting in the case instead of the reservoir, making the case too full?

I dont know if this would make a difference or not, but have you checked the oil screen going from the reservoir to the motor?

[mstngmatt]

Originally posted by Honda_Matt
It sounds like the oil is sitting in the case instead of the reservoir, making the case too full?

I dont know if this would make a difference or not, but have you checked the oil screen going from the reservoir to the motor?

Thanks, but the screen is clean. Any other ideas

[Knoxy]

replace the oil pump gaskets on both pumps... this might be a bit of a big job... but if your gettin oil blowing out the breather... then i think you might have a leak in one of the pumps.... i haven't seen one of these wear out yet... but it sounds like the next step if the rings and pistons are new! good luck my friend!

keep me updated

[mstngmatt]

Wow has anyone else had a problem like this.......Pump gaskets no big deal but it is a lot of work. Is there a way to test the pumps somehow?

[#17YFZRACER]

the oil check bolt on the head. take it off and there should be oil coming out.

[leveldrummer]

the oil goes from the engine, to the little black box under your rear fender, once it fills that up, it will start to blow into your air box... right? have you pulled that little black box and cleaned it?

or i could be confused, if so... disregard.

[quaddad#123]

we have two yfz's one blows a little oil one does not.I took the black box off and run the oil line into a small k&n filter that will atleast keep the oil out of the air box. This might not help if your loosing alot of oil. Some people just run the line down to the ground between the swingarm.

[mstngmatt]

Originally posted by #17YFZRACER
the oil check bolt on the head. take it off and there should be oil coming out.

What will this do?

[mstngmatt]

Originally posted by quaddad#123
we have two yfz's one blows a little oil one does not.I took the black box off and run the oil line into a small k&n filter that will atleast keep the oil out of the air box. This might not help if your loosing alot of oil. Some people just run the line down to the ground between the swingarm.

In the end this may be what I have to do. I'm sick of cleaning all the oil off the filter and in the airbox every ride. I'm still curious of the cause!

[Knoxy]

i dont know what black box your talking about?
i hope your not talking about the brake reservoir.

the little black box underneath the left hand side fender?
:confused: :confused: :confused:

i think that that is the breather for the crank and cylinder... as per the drawing? i have no idea what those are for!

here is the oil flow diagram
maybe you have too much oil in your tank?
i had a buddy that put too much in and it pissed out everywhere

the diagram see below!
let me know what happens with this

check your breather hoses. make sure nothing is stuck in them or blocking air flow. make sure your crank case breather is clean. if your oil is not over full and your screen is clean and you just did the top end it sounds like you have something blocking your breather hoses. do you wheelie alot? that will also cause oil to flow into the airbox causing your problem.

[atva_63]

This is a very comon issue with the yfz especialy when they are ran hard or raced. Save your money on the rebuild. Go to a hardwere store and buy about 2-3ft of hose and run it from the crank case up around your motor and down in front of youy radiator to the ground. Any one who has raced these knows about this problem. It doesn't hurt anything it is just "blowby"
check your oil.