-03 YZ450F oil piston ring installation

[Anssi]

Hi,

I´m doing some maintenance and can´t remember how the corrugated oil scraper (that has the two thin rings in the same groove in the piston) goes in. I know it has to go in before the accompanying rings because of the notches and that the ends should not over lap. However, I don´t remember whether it matters which way the ends point, up or down?

So, _/gap\_ or \gap/ ?

I thought the manual had a picture of this, but the pic must´ve been in the instructions for the big bore kit that my dad got for his 450 and is now lost.

[grayracer513]

I'm not sure I understand your question entirely. There is no right side up, upside down on the oil ring expander. Put the expander in, and butt the ends together. Do not allow them to overlap.

The rails, or scrapers, must sit above and below the center of the expander, against the small ledge on the inner diameter with their end gaps located way from the other gaps in the oil ring. Refer to the manual for the correct ring end positions, and note that in the illustration, "d", the "oil ring" refers to the end of the expander.

[JohnRM]

Grayracer the ends of the corrugated ring are like a "V". I think Anssi possibly means should the "V" point up or down. Does it make any difference?

[grayracer513]

Odd. Normally, the expander ends would butt squarely when viewed from the side of the piston. If there is any kind of paint mark, etc., on one side or other of the expander, and no instructions to the contrary are in the ring package, I would assume that to be the top of the expander. Otherwise, check with a dealer tech, or take your best guess. It shouldn't make a big difference, but they must have had something in mind.

[Anssi]

Yes, what I mean is that the end do indeed point up or down (so if you flip the ring, it will not look identical (where the ring continues, the horizontal parts of the ring will be either on the upper or the lower edge of the rim, so johnmeasures figured out what I meant)). I thought it makes little difference so just put it in and it runs great.

I did position the end gaps as per the manual and did remember(have done 2 YZ450F top ends before) and check from previous posts that the ends should not overlap.

Thanks for the help, guys.