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02 yz250f oil drain problems

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I got a 2002 yz250f a few months ago, and I checked the oil. It was really high, so I tried to drain some. It would only drain a little bit. After some fiddling and a new oil pump, it won't drain very much unless I run it for a little bit. Is this normal or what's messed up so I can fix it?

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Ah,...... There's 2 places to drain.  The front down tube tank... in front... down just above where it splits into 2......AND..... the drain bolt on the left side of the case down near the shifter.  You should run the engine enough for the oil to get warm and fill the frame tank.  Then remove the bolt and drain there.  Replace the bolt being careful not to strip it out and move down to the other drain.  Drain the sump, then replace the drain bolt being careful not strip it out.  Then move around to the right side and remove the oil filter and replace with a new one.  The book says replace the o-rings, but if you're careful, they can be re-used.  DO NOT overtighten the cover bolts when you bolt it back up.  MEASURE out 1.25 qts of good quality oil, proper viscosity, and add that to the crankcase and put the cap back on.....being careful not to OVER TIGHTEN it.  Get a 10mm box wrench and find the oil line on the right side of the engine that goes up to the head.  Crank the engine and let it idle while loosening the bolt on the head in line with the oil line.  That is a check to make sure the pump is pumping oil up to the head.  When oil comes out, just snug it back up ..... you got it.... being careful not to OVER Tighten it.    Check your work..... look at the dipstick after you run it and add to bring it up to snuff.   U R dun.

Edited by ronbuell

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Is it normal for it to not drain if it isn't warmed up? I noticed that more comes out the longer I let it run. I don't want it to run for too long for fear of engine damage. I know oil is at least getting to my clutch because that works, and it needs oil to work.

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Ok, I got no idea how much experience you have, so I have to assume minimal.

 

When the engine has not run, the oil all drains into the sump in the bottom of the engine.  When you crank it up, oil is carried up to the top end by the cam chain and splashes around.  As the engine runs, the level in the bottom end drops, the pump pressurizes the oil lines and oil is pumped into the tranny and into the lines going up to the head and into the oil tank in the frame where it sits ready to be pumps thru the oil pump system.  That's why you check the bolt at the head to make sure pressure is present for the head to be lubricated.  After 5 min of run time, the oil tank in the frame should be full and the oil warm.

 

The oil is thicker if cold, thinner if warm, so it runs out easier if warm.  But the main reason for warming it up is to get the dirt into the solution so that it comes out with the oil and does not remain in the sump.  You can drain it cold, but, you leave the sludge in the bottom end when you do that which is not what you want.  The sludge then gets pumped in with the new oil ruining your new oil.  Eventually this will cause a lot of wear.

 

Now, for some background, your typical 4T runs 4 qts of oil, but these are race bikes and only run 1.25 qts to save weight.  So the factory assumes you will do due dilligence maintenance; oil changes, air filter, bearing greased etc.  Since it only holds 1.25 qts, the oil molicules get sheared or broken down much faster time wise.  So after 5 hrs of run time, that 1.25 qts is done.  Get an hour meter and use it.  Change your oil at 5 hrs and clean your air filter every 1-2 rides or if riding dusty conditions, every ride.  Personally, I like the WR airbox because it protects the filter much better and the filter stays clean much longer.

Hope that helps.

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I have some experience with bike motors. Half of them 4 stroke. My brother also has worked on dirt bikes and has quite a bit of experience with them. The problem isn't how to change the oil. That's a fairly simple process. The problem is the oil doesn't drain at all. My brother had practically the same bike and his didn't have this problem. I know that warming up the bike before changing the oil cleans everything out. I'm just trying to figure out why it won't come out at all when cold. We can't figure out why. The guy who owned my bike before me seemed like an idiot. There are little thing he did like put the handlebar clamps on backwards. He also rebuilt the engine so I'm hoping he didn't screw something up.

 

Thanks for the effort.

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Do you know the bike has two drain locations, one for the engine and one for the oil tank in the frame?

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"....The problem isn't how to change the oil. That's a fairly simple process. The problem is the oil doesn't drain at all......."

OK, gotcha.

 

Then I'd say there is a venting problem.  There's a oil vent overflow (small tube) and the crankcase vent (larger tube) on the valve cover.  You need to check those for blockage.  Also there was a wetsump conversion that could have been done, and I'm not at all versed with that one.

 

After one of my rides, the crank vent hose got crimped at one of the metal clamps down near the shifter.  I didn't see it at first but it was preventing proper air flow on mine, so you might check yours.

 

Beyond that, I'm at a total loss as to why it won't drain out unless you are using molasas for oil (50 wt).

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how about a really blocked strainer in the frame tank.

Also when draining, take out the dipstick and any other breathing point, as you get nothing out, without putting air in.

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I let it breath to drain the oil. I know the oil goes through the frame tank. I've disconnected the oil pipes (which are clear) and let oil flow right through. I think the problem is in the motor, but I don't know where. I really don't have the time or experience to split the cases. The person that helps me with my engine work leaves for 2 years soon. The farthest I've dug into the engine by myself is The inner clutch cover and dug out the oil pump. I don't think the problem is in there. Is there something I'm missing?


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Okay. We checked that and it's clear. So far nothing has worked. We've made sure every hole we could find that oil would flow through is clear. The oil is getting to the inner clutch cover because oil is leaking from a torn gasket, but It's not getting to the drain plug. Any ideas?

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OK, I'm going out on a limb and really stretching it.

 

Somebody poured Yamabond in the bottom end, sloshed it around, then left the plug in.  So when you remove the plug, the hole is actually covered with a thin film of sealant and it won't allow oil to drain out.  Take a screwdriver and poke it in the hole to break it out.

 

That's my one best shot.  Baring that, maybe a piece of gasket material is blocking it,......

Edited by ronbuell

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I accidently dropped the ball that goes to the clutch and we got it out through the drain plug, so that's not the problem. Thanks for the shot though. We can check all the gaskets again, but so far they seem to be in the right place. The only one in the bottom end we haven't checked is the one in between the cases. It looks like it has gasket maker on it. Would gasket maker be able to seal off a hole without getting shoved in the hole?

Edited by JG12YZ

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