06 YZ450F Oil Scavage Screen

I recently changed the oil on my 450 for the first time after break in. I noticed there is no scavage screen to to check or clean. All my other YZ thumpers had one and even my 06 YZ250F has one. I searched the service manual and found no mention of one. Does anyone know why?

It wasn't a scavenge screen. That's been in the crankcase all along, and has never been serviceable short of splitting the cases.

The screen was the feed oil screen, and the reason it isn't serviceable on the '06 450 is because the oil tank is integrated into the crankcase assembly, so that if there were one, it would also be internal, as the return screen is.

As to why there is none, I don't know, but as I see it, there are 3 reasons that might have lead to that:

1> They didn't think it was needed, since the return screen is the front line against big chunks already. A wet sump engine only has one screen, and dry sump engines only have feed screens because they can.

2> Because of the cramped nature of the area the screen would have to go, they didn't feel they could put one in place without compromising something.

3> They didn't want to put a feed line screen in the engine without making it serviceable, and doing so would have been more effort than they wanted to put into it. On virtually all British dry sump bikes, there was a provision for accessing both the feed oil screen AND the scavenging screen in the crankcase from outside. These were either plugs or plates, and being British, they leaked. They could have included a serviceable feed screen, but the most workmanlike method would have added a specially machined plug/screen, and some extra machine work in the crankcase. They probably just didn't think it was worth it.

Thank you so very much for the explaination. I was real curious about that and did not want to skip anything on servicing the bike. Now that , that is resolved, it's time to load up and ride....Thanks again!!!

...and being British, they leaked.

:thumbsup: yes, tell me about it...

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