too much oil plain and simple

 

nope, thats not it.

ive changed the oil alot and always put the same amount in and its never done this. it will do it when the oil is perfect on the dip stick or even when its reading low, it still blows it out.

 

Sounds to me like maybe a busted ring & your getting tons of blow by into the crankcase & thru the hose into the airbox... :what

 

Brad, I sent you an email.........I will get a quote for a top end together in the morning.

Paul

 

Originally posted by brad c@Jan 30 2005, 03:52 PM
at the races this weekend my yfz started to blow alot of oil into the airbox from that hose that goes in the side. when i come off the track the oil is running out of the airbox drain like crazy.

im sure this isnt a good thing, but what needs top be done now to fix this? it dosent feel down on power or anything, but i know it has to be motor related.

thanks

i had the same problem
for me it was because i glued the small rubber in the head .... the rubber tried to come of .. so the oil came from the filter box....
this is what i did
i changed oil
i cleaned the black bottle beside the filer box
changed the small rubber
............

 

what small ruber are you talking about?

 

seen this several times..............once there is oil getting forced out of the breather the engine is fuming real bad with loss of compression into the low end for sure.

if your running a gytr piston, good chance the crown has cracked, we have killed three at national level racing. They run strong until a chunk literally cracks clean open in the piston crown............. but are fuming / blowing maybe a litre into the airbox in one race !

Strip it down now and check the rod / small end pin bore also, when worked hard they tend to pick up / gall the small end pin bore in the rod. Yamaha changed the oem pin, they no have a special coating, the pin appears a dull grey colour compared to the shiny chrome finish they used to have...............

:bawl be prepared for a full rebuild.

 

thats not what i wanted to hear. :cry

 

Originally posted by brad c@Feb 1 2005, 06:40 AM
thats not what i wanted to hear. :cry

Keep us updated on the problem with your quad. If all this is true.........that sux bro. :disgust

Good luck. :re

 

that happened to me also. It blew into the airbox, then the breather tube fell out of the airbox and threw oil all over my swinger. Ends up that my motor had sucked in dirt and i blew the top end and cylinder.

 

ctyfzrider, what all did you have to replace when doing the rebuild?

im also not sure on where to send my motor, and if i should just go ahead and get it built up a little or not.

the thing is that its still running great, no smoke or anything, its just blowing alot of oil in the airbox up during races.

 

Originally posted by brad c@Feb 1 2005, 08:53 PM


the thing is that its still running great, no smoke or anything, its just blowing alot of oil in the airbox up during races.

Mine start to do that today :madashell

No smoke, the bike run well... :bawl

 

So dose any one have some more info on this????


Just recently this has started happening.

A guess......... is that when I stand the bike up on the grab bar to wash it oil drains into the little black box from the starter cover, then mixes with water in the black box, and blows in on the air filter.

But then I could be compleatly wrong on this and I have some serious proplem????

The bike runs strong and no water is getting into the oil tank. I raced two classes and a lot of oil was getting into the air box, about two table spoons.

If anyone has more info please post it thanks.

 

Originally posted by brad c@Jan 30 2005, 06:52 PM
at the races this weekend my yfz started to blow alot of oil into the airbox from that  hose that goes in the side. when i come off the track the oil is running out of the airbox drain like crazy.

im sure this isnt a good thing, but what needs top be done now to fix this? it dosent feel down on power or anything, but i know it has to be motor related.

thanks

[snapback]199994[/snapback]​

Maybe a little off subject, but does the hose running from the airbox to the engine have a filter somewhere in it? Notice the black box that the hose enters from the air box? Is there a filter in there? Yesterday I noticed that my hose was hanging loose from the airbox. :wtf: I forgot to re-insert it after my airbox mod.

It seems to make sense that this hose should have a filter in it.

 

The 2 main reasons for getting oil out the breather are, #1 Bad rings, getting compression into the crankcase and out the breather tube. #2 High rev, if your hitting the upper end of your rev box you will also get some amout of oil out you tube. Yamaha says this is normal. I discontected the tubes out of the Airbox and threw away the black box and added 2 small Uni Filter mounted by my coolant res bottle. The only reason the tube goes into the air box is because the EPA doesn't want it on the ground.

 

Originally posted by yfz450mx77@Apr 4 2005, 07:02 AM
The 2 main reasons for getting oil out the breather are, #1 Bad rings, getting compression into the crankcase and out the breather tube.  #2 High rev, if your hitting the upper end of your rev box you will also get some amout of oil out you tube.  Yamaha says this is normal.  I discontected the tubes out of the Airbox and threw away the black box and added 2 small Uni Filter mounted by my coolant res bottle.  The only reason the tube goes into the air box is because the EPA doesn't want it on the ground.

[snapback]231592[/snapback]​

this is true......... there is a small amount of oil that leaves the engine as it vents. the little black box on the side of the sub frame, by the coolant bottle, has foam in it to absorb the excess oil. eventually it will fill up and blow into the air box. most pro riders connect the two motor vent tubes together by the carb, and rout the exit underneath the bike. the yz dirt bikes vent the oil into the frame.
I had the same problem and I thought it was blow-by. but the motor "leaked down" ok, still ran strong, then I noticed how the tubes were routed on Kory Ellis's bike. now mine are like his.