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Where did my oil go? '10 Yz450

By vomitbomb,
in YZ400F/426F/450F/450FX

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vomitbomb

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Hi All,

I checked my oil after around 120kms (75miles) of riding and must have put what felt to be around half a litre of oil in it to get it back up to spec. I have no idea where the oil has gone as I can't see any around the engine and I checked the oil drain bolts which were nice and tight.

Two things to note:

  • I did notice the gear lever being unusually hard to move lately if that has anything to do with it. or is that a symptom of low engine oil?
  • Before this I had fully synthetic in it, but the shop only had semi synthetic this time around.

It's a bit concerning seeing as though my 2008 WR was always spot on and never seemed to burn even the slightest bit of oil. Is this behaviour at all common for a YZ?

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SEOINAGE

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ummmm, are you checking your oil after letting it run for a few minutes? because that is what the manual says to do, you might have way too much oil in there now. it shouldn't show up in the site glass until after you let it run.

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vomitbomb

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Now what on earth made anyone think I had checked it while cold?

No, I definitely checked it after it had been warmed up (as per the manual).

Could out of spec valves somehow be throwing out oil? I don't really know what to think. I was a bit confused when I couldn't get an oil reading.

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grayracer513

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Could out of spec valves somehow be throwing out oil?

No.

Oil can only disappear by one of two paths; either it leaks or you burn it.

The most common reason for burning oil in an engine that new is a damaged bore and/or rings. Occasionally, something goes wrong and the engine eats something or partially seizes and there you are.

If you verify that it's using oil, and you can't account for the loss in the form of a leak, open the engine up.

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vomitbomb

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I've checked the circulation (pressure check bolt) and it's all good.

I'll take the engine oil out soon to see how much comes out.

Grayracer, If the bore/rings were damaged wouldn't I see smoke coming out of it?

And when you replace the oil in these things do you wait until is starts leaking out the overflow bolt (behind the gear shifter) or do you put what you think is the right amount and then run it for a while to check? I know this is what the manual says but I thought the other method would be a lot easier.

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grayracer513

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And when you replace the oil in these things do you wait until is starts leaking out the overflow bolt (behind the gear shifter) or do you put what you think is the right amount and then run it for a while to check? I know this is what the manual says but I thought the other method would be a lot easier.

If you drain from both plugs, and service the filter, the bike will take one liter of oil exactly. That works every time, and there is no need to ever bother with the overfill plug. One quart without the filter.

Regarding the overfill plug, the manual does not say that you are to fill the oil until it comes out the bolt. That would cause you to short fill the oil by a huge amount. The manual tells you on page 3-9 that only if the oil shows above the high limit mark in the fill window do you then remove the overfill plug. The way it works is that there is no additional room in the oil "tank" for any additional oil, and anything extra gets routed back to the sump. The overfill plug then is set at the highest level oil should be after the engine has been run and all the normal amount of oil has been pumped out of the sump, leaving it "dry". If you were to fill only to that level, there would be almost nothing in the engine.

If the bore/rings were damaged wouldn't I see smoke coming out of it?
In order to burn 100cc of oil in an hour, there would need to be only one half microliter of oil (0.0005cc) in the cylinder each time it fires, figuring an average of 6000 RPM. That's not going to make a whole lot of smoke, but yes, there probably would be some.

Review your oil fill procedure again, then worry about it.

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vomitbomb

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If you drain from both plugs, and service the filter, the bike will take one liter of oil exactly. That works every time, and there is no need to ever bother with the overfill plug. One quart without the filter.

Regarding the overfill plug, the manual does not say that you are to fill the oil until it comes out the bolt. That would cause you to short fill the oil by a huge amount. The manual tells you on page 3-9 that only if the oil shows above the high limit mark in the fill window do you then remove the overfill plug. The way it works is that there is no additional room in the oil "tank" for any additional oil, and anything extra gets routed back to the sump. The overfill plug then is set at the highest level oil should be after the engine has been run and all the normal amount of oil has been pumped out of the sump, leaving it "dry". If you were to fill only to that level, there would be almost nothing in the engine.

Hi Gray,

I know the manual does not say to check/fill it with the overflow plug. I meant the manual says to fill/run/sightglass check. I thought I'd seen mechanics fill using similar methods (until the oil comes out a certain bolt) but it sounds like this is definitely not the case with the YZ. Good to know, thanks mate.

I'll keep an eye on the oil situation and if it continues I guess I'll have someone pull it apart.

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ttr250dude

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I'll keep an eye on the oil situation and if it continues I guess I'll have someone pull it apart.

Instead of paying someone else to do it, i would buy a service manual and try it yourself first to save a few bucks. I was a little nervous the first time i pulled apart a 4t engine but if you have the service manual and are mechanically inclined it's not too bad. But if you feel safer bringing it to a mechanic, i totally understand :cheers: A heads up: A shop/service manual is different than an owners manual.

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powers450f

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Instead of paying someone else to do it, i would buy a service manual and try it yourself first to save a few bucks. I was a little nervous the first time i pulled apart a 4t engine but if you have the service manual and are mechanically inclined it's not too bad. But if you feel safer bringing it to a mechanic, i totally understand :cheers: A heads up: A shop/service manual is different than an owners manual.

A service manual comes with any bike you buy brand new.

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Pmason718

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lol Seven manuals came up. lol One of them was for the YZ450. lol

Focus

lol

I actually found it. I put in 2010 instead of 2011 and it came up. I know there the same bike but for some reason the 2011 would show the R6 and R1. I thought the manual would have sections showing you how to get to certain things. I'm trying to find a video or something that shows me what I need to remove to get to the spark plug, I would like install an hour meter

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