Is this normal?

[Slowmotion426]

I have a '01 YZ426F. I was going to adjust my valves, took out my timing caps to make sure I was on the compression stroke and oil came out. I posted on this earlier. Some said that it was normal for a 'little' oil to be in there. So after letting it sit for a week now (due to a lot of overtime at work stopping me from working on it) I removed the left side case cover just to have a look and i'd say nearly all the oil in the bike came out. Is this normal guys? Thanks in advance for your advice.

[grayracer513]

Yes, it's normal. You know it's a dry sump, right? The oil supply is supposed to reside in the tank while in operation except for the oil that's actually being circulated. The oil that drains back to the bottom gets sucked up and returned to the tank as fast as it can.

But when you let it sit a while, gravity conducts a sneak attack, and in spite of a low pressure check valve intended to prevent this very thing, oil slowly seeps by the pump shaft and into the engine. Eventually, it could all end up there.

Just remember that when you cold start your engine after two weeks rest: the oil tank may be dry for the first 15 seconds! So take it easy. That's also why your manual says to run th engine before checking the oil level.

[Slowmotion426]

Yes, it's normal. You know it's a dry sump, right? The oil supply is supposed to reside in the tank while in operation except for the oil that's actually being circulated. The oil that drains back to the bottom gets sucked up and returned to the tank as fast as it can.

But when you let it sit a while, gravity conducts a sneak attack, and in spite of a low pressure check valve intended to prevent this very thing, oil slowly seeps by the pump shaft and into the engine. Eventually, it could all end up there.

Just remember that when you cold start your engine after two weeks rest: the oil tank may be dry for the first 15 seconds! So take it easy. That's also why your manual says to run th engine before checking the oil level.

Gray, that's the best explanation i've ever gotten. Thanks for your help and experience.