exhaust blowing oil

[450rJam]

I know this is an atv forum and I love my 450r
but I have a problem with a dirtbike I just got for my son.
its a 1999 cr80 and it runs great but it has oil blowing out the exhaust, not a lot but enough that after he rides it there is a dribble, (also a small amount where the exhaust exits the jug)
the guy I bought it from said the top end was pretty new
its got aftermarket exhaust/bars etc
thank you for any info you guys can share.

[Iliketogofast]

i didn't see where you said it was dripping at the exhaust port. That's somewhat normal - if you want it to stop you need to either get more air to the motor or less fuel- jet leaner or put some holes in the airbox or something.

[450rJam]

its blowing out the exhaust collar where the head pipe meets the motor and a small bit out the silencer.
I have had 2 stroke dirtbikes a long time ago and dont remember them doing this, I also had a 250r that I just sold and it didnt do this at all.
Im thinking the only way for the oil to get out the exhaust is that its not getting burned on the way through the cylinder but im not sure what would cause that, its not blowing alot of smoke its just after he rides it it has splatter at the motor and a little at the silencer. I can take a pic after work if it will help.

[Iliketogofast]

Originally posted by 450rJam
its blowing out the exhaust collar where the head pipe meets the motor and a small bit out the silencer.
I have had 2 stroke dirtbikes a long time ago and dont remember them doing this, I also had a 250r that I just sold and it didnt do this at all.
Im thinking the only way for the oil to get out the exhaust is that its not getting burned on the way through the cylinder but im not sure what would cause that, its not blowing alot of smoke its just after he rides it it has splatter at the motor and a little at the silencer. I can take a pic after work if it will help.

I know what you were talking about now. You probably need to jet a little leaner - my 250 did that when I brought it back from Missouri until I took the time to jet it properly. Now it doesn't do it anymore.

Pull your spark plug out and tell me what it looks like.

[450rJam]

well I pulled the air filter and it didnt look bad until I sprayed the cleaner on it..........wow it looked like draining a mud puddle.
the gas was also mixed way rich. he used full synthetic and mixed it 20:1
I filled it with 40:1 klotz and the cleaned filter and replaced the plug.
I thought it ran good before but this is a different creature
no more oil blowing and no more hesitation.
this thing is impressive for an 80cc motor.
I paid $1,000 for it with new graphics and new fenders (front and back)
I wonder if he sold it because of the hesitation and not running right ?

my rm125 did that i just left it