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Mysterious disappearing oil

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I'm so confused... I don't know where my oil is going. It's not puffing excess smoke during any time of operation, it's not slipping into the tranny-side, and it's not leaking. Where else could it possibly be going?

So - anyone have any thoughts on this? Where should I start in diagnosing it?

I'm losing about 1/3 qt. of oil per 45 min. I consider myself a decent mechanic... but I can't seem to figure this one out.

Thanks,

Jeff

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Probably burning it!! You wont see the smoke unless you can ride behind yourself under high load conditions. I bet its time for a set of rings. How many hours on the top end?? It could also be getting blown out the crankase vent tube? If you dont have the cap on it??

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Probably burning it!! You wont see the smoke unless you can ride behind yourself under high load conditions. I bet its time for a set of rings. How many hours on the top end?? It could also be getting blown out the crankase vent tube? If you dont have the cap on it??

1/3 of a quart is half what the engine holds. To burn that in 45 min would leave smoke hanging in the air almost...hell, its running at just under 100:1 like a two stroke if you do the math...

Have you modified the breather location? It could be blowing it out the breather tube and onto the ground if you have rerouted the breather hose. But even then, Id think there'd be oil on the linkage and stuff underneath. Do you have foam in a skid plate? Could that be soaking up a leak?

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check the tranny level oil
it's not slipping into the tranny-side, and it's not leaking. Where else could it possibly be going?

Seems like he's already looked for that, but its the most common place.

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did you put the drain bolt back in? all 700cc out of the motor in a ride is excessive. If it is not going to the tranny side, and you are keeping the bike upright you have serious issues. You would be able to see the bike like a cloud behind you if you are burning it.

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That's exactly what is blowing my mind about this whole thing. I was riding trails with a bunch of guys and none of them thought I was blowing excessive smoke. One of the my riding buds thought valve guide seals, but on start up it didn't smoke either.

I did lay the bike down a few times, but normally they were little flop-overs in tight woods sections and I picked the bike up pretty quickly. We unplugged the breather tube and there wasn't an excess of oil there either.

20 hrs ago I replaced the head with a bigborethumpers.com head with SS valves & a new '04 piston, so it should be fine.

I'll take another fresh look at it with a clear head again this weekend. I'm so perplexed. :lol:

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Excessive smoke? There should be no smoke at all

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I don't want to get lost in the weeds on semantics... but there wasn't any smoke above and beyond what you'd see from a normal, healthy engine.

if you eave any healthy bike running in a closed garage, it will get smokey in there.

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I don't want to get lost in the weeds on semantics... but there wasn't any smoke above and beyond what you'd see from a normal, healthy engine.

if you eave any healthy bike running in a closed garage, it will get smokey in there.

Running in a closed garage?? It still shouldnt get smokey with a 4stroke. You will however affixiate yourself with carbonmonoxides!!! You should only see a little brown or blackish smoke when you crack the throttle hard. Not under load that is! Otherwise there should not be any smoke.

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I was one of the guys riding with him the entire weekend. There is NO visible smoke on start-up, acceleration, or decel. Nothing!

As stated, with the amount of oil loss, if it was being burned, I would expect to have a blue haze everywhere he rode.

None of the riding was at high RMP either.

The underside of the engine was dry.

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I was one of the guys riding with him the entire weekend. There is NO visible smoke on start-up, acceleration, or decel. Nothing!

As stated, with the amount of oil loss, if it was being burned, I would expect to have a blue haze everywhere he rode.

None of the riding was at high RMP either.

The underside of the engine was dry.

The way I see it, if no oil is coming out anywhere, you'll eventually see where it's going to if you keep filling it with oil :lol: . That's what I did with my bike, and it worked! lol

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Yeah... I'm with Shawn. Also, try rubbing your finger on the inside of the exhaust pipe, and see if you get any oil on your finger.

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open this cap and see if the trans level is about at the level of the small level screw, if you pull the cap and a bunch of oil comes out you know it migrated past a seal OR you mistakenly overfilled the trans last service.

crank-hole-plug-1.jpg

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open this cap and see if the trans level is about at the level of the small level screw, if you pull the cap and a bunch of oil comes out you know it migrated past a seal OR you mistakenly overfilled the trans last service.

crank-hole-plug-1.jpg

Thats not exactly right...

That screw has a procedure youve gotta use to use it correctly. Youre supposed to start the bike and run it until its warm (3 min) then check the screw hole. If you dont, the oil will have migrated around to the bottom of the clutch catch basin and will give you a false high reading.

But if youve topped the motor off twice and check that inspection hole he's showing you and you get oil out of there...you've definitely got a bad seal at the crank and its allowing oil to migrate from the engine side to the trans.

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Funny story... I'm having just the opposite problem.

Somehow I have more oil in my bike now than I started with.

I just took out 500ml from the engine side... and I only put 700 in, and now it's at the appropriate level (not my CRF450R). Tranny side was over filled too. lol. Radiator is full... IDK where all this could be coming from.

AND... I've done this twice now. lol

It's fine now though???

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Thats not exactly right...

That screw has a procedure youve gotta use to use it correctly. Youre supposed to start the bike and run it until its warm (3 min) then check the screw hole. If you dont, the oil will have migrated around to the bottom of the clutch catch basin and will give you a false high reading.

But if youve topped the motor off twice and check that inspection hole he's showing you and you get oil out of there...you've definitely got a bad seal at the crank and its allowing oil to migrate from the engine side to the trans.

Or you can just put in the recommended amount..

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