oil dripping from breather tube

[BigMiniRider77]

ive got an 06 yz450f and i havent ridden it in 6 months, but this morning i took it out and it blew black oil out of the breather tube all over the chain, swing arm, tire (which slung it back onto the motor and up underneath the fenders). I had just replaced the throttle and put new tires and i think i just changed the oil but forgot to kick out all the old ****. Anyways i rode it for about 15 minutes and it was still dripping when i had stopped. It has done this before just not this much oil has ever come out. It normally would just drip when i would stop, never drip so mush it was getting sprayed everywhere.

Any ideas if that is just normal or what?

 

[nickv1980]

Sounds like either too much oil in the motor or excessive blow by past the rings

Sent from my HTC One M7

 

[my67xr]

i just changed the oil but forgot to kick out all the old ****.
Any ideas if that is just normal or what?

does that mean you put the new oil in on top of the old oil?

 

[BigMiniRider77]

ya i heard it might be blowby but how do i tell for sure?

and when i didnt kick the old **** out i meant i drained it but i didnt turn the motor over so there might have been .16 of a quart of old oil left in there.

 

[my67xr]

ok, that's fine with the oil level then...


the blow by can be caused by too much oil in the crankcase,
and also by a worn piston and or rings.

with worn rings/piston, it allows some of the compression to get past the rings and blow into the crankcase, splashing the oil etc around, and adding extra pressure inside the motor.
this extra pressure gets blown out of the breather hose, spitting oil etc



when you fitted the new throttle and took it for a ride, is it possible you may have revved it out a bit more than normal ?
if so the piston and rings may have travelled a little bit further up the top of the cylinder and into some built up carbon/oil etc
the carbon could be stuck in the rings and is making them sticky in the pistons' ring grooves ?
this would stop them from springing out and sealing on the bore of the engine, and allowing the blow by.

 

[nickv1980]

Excellent explanation Craig I'd say it's blow by for sure ....if you comp test it check the specs on cylinder compression and see if it's on spec or low

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[my67xr]

cheers,
worst thing is, i can picture it all in my head,
but putting it down in text is hard, especially explaining what/how/when etc
i usually have to edit my post 5 times or more to check i have said the right things, lol
i never did too well when i was at school, last book i read, i think was in grade 2 ?

 

[nickv1980]

Funny you should say that im exactly the same mate

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[BigMiniRider77]

when i put the new throttle on i never took it for a ride i just let it sit for 6 months, but when i started it this morning it was not really wanting to idle until i rode it, then it had no problem idling. also i noticed the throttle was kind of running on a tab bit when i was revving the engine on initial start up; however i think that might be because i need to lube my cable.

 

[zwebx]

or even start it up and open the oil cap a little but and you will see how much pressure is down there (its usually messy though)

 

[GooseMan]

I have heard of a few people putting in too much oil before and this being a result, so I would suggest draining the oil and measuring how much come out and double checking it with the specification. Otherwise a s mention it could be blow by.

 

[BigMiniRider77]

i think it was just overfilled its not dripping anymore

 

[nickv1980]

try not to do that too often mate it can end up expensive