WTF...Black oil???

My buddy has an 04 yz450. he bought the bike used. last weekend he changed the oil in the bike and rode it on saturday for about 3 hours. this weekend we drained the oil so he could put a new clutch in an the oil came out black. i checked my bike's (2002 yz250f) oil just to compare it. my bike was a very faint brown, almost the same color as when the oil was new. we also changed his oil filter and when we inspected it after a few hours of riding, it was completely black and the filter itself was sort of frayed. it wasnt ripped, but it looked like the filter fabric was getting roughed up. i checked mine and mine looked like i just put it in, even though i havent changed mine for at least 3 oil changes.

that was the first thing that struck me as odd.

also, his bike would leak oil from the breather hose on top of the engine. i have never noticed a yamaha actually leak oil out of that. the amount of oil noticed was about a half dollar amount.

I checked his valves and everything is in check. the exhaust cam's valves are right at .25 mm.

so what are your ideas? think everything is ok or what

thanks for any responses

I am just taking a stab at this but it sounds like it needs some new piston rings. This is my first four stroke. I have had 2 smokers since i was 5. Do a compression check on the bike to verify the rings are lettings burned gasses past the piston and into the crank case. The carbon from the burnt gasses could be dirtying the oil prematurely. Just my guess though.

It will probably need about 2-3 changes to get all of the oil out. Try changing it a few more time before you jump to any conclusions.

^^^what he said...change the filter too!

It's just really dirty oil, whoever owned it before him didn't change the oil often then I take it. Just like my uncle, buys all these toys, never takes care of them, lets them rust to hell, for fun I checked his oil in his quad, pitch black, its a 2000 model, and I don't think he has had it changed once, maybe once when he got it serviced for a recall but that is it. And theres a lot of miles on the thing....he don't care though, he will just go out and buy a new one when it breaks (must be nice to have that kind of money).

Just keep changing the oil regularly, it will clear up.

how can people do that? I'm changing the oil probably more than recommended because I want my 'toys' to last me...I just don't have the $$ to be throwin' down the tube I guess.

how can people do that? I'm changing the oil probably more than recommended because I want my 'toys' to last me...I just don't have the $$ to be throwin' down the tube I guess.

Yup, same here. I change mine like every 5-6 hours, and oil filter everyother oil change.

If the oil that was removed from the bike when he first changed it was also black, it may be that the new oil is simply cleaning up the mess left by the previous owner. If there is a lot of sediment lying around the interior of the engine, this could take three oil changes to clear up.

As to leaking from the breather, be certain the bike is not overfilled. It takes 1.1-1.2 qts. with a filter change. You can run as much as 1.5 in it with no trouble, but when you get to around 1.9 qts., it starts spilling back from the tank to the engine. Overfilling most commonly happens when the person changing the oil fails to drain both the tank and the crankcase and then refills with the full amount.

But, if both the excess in the breather and the blackening of the oil continue, it may very well be time for rings.

he drained the front frame bolt and the one by the shift lever under the motor. he has changed the oil twice in the machine and its still dark. when do you think its time to just buck up and put a new set of rings/piston in?

Was the filter changed out?

Black oil sounds like clutch plates. Check that out before pulling your top end. Sometimes the oil smells like burned cork.

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