Which is the top piston ring?

Long time lurker, first post!

Just doing a rebuild on a 2011 YZ450F and am about to put the rings that came in the spares kit on a new oem piston.

Which is the top ring and which is the second?

1. Black and chrome in colour.

2. Grey in colour with a chamfer on its outer edge.

Cheers.

I have put them in, in the order that I decribed them. Ill see what happens. The top one also has the smallest ring gap which I think is right.

I have put them in, in the order that I decribed them. Ill see what happens. The top one also has the smallest ring gap which I think is right.

Are you kidding? Guessing on which ring goes where? Good luck! This is why I don't buy used bikes!

They should be of different thicknesses...check the ring grooves on the piston and compare to the thickness of the rings.

If they fit, they're in the right place. One is wider than the other, and they can't be switched. That's why they come with no identifying marks as to which one is which.

If there are any marks on the rings, they face up.

If there are any marks on the rings, they face up.

That's one of the very few things that IS in the instruction sheets (most of them), but it's worth mentioning.

That's one of the very few things that IS in the instruction sheets (most of them), but it's worth mentioning.

My pop learned me a long time ago; men don't read instructions.

Thanks for the replies fellers.

Are you kidding? Guessing on which ring goes where? Good luck! This is why I don't buy used bikes!

I brought the bike new last year. I've put 120 hrs on it so I figure it's time for a freshen up.

I am replacing valves, valve cotters, valve stem seals, valve springs, piston, rings, piston pin, cam chain and cam chain adjuster. All OEM parts.

If they fit, they're in the right place. One is wider than the other, and they can't be switched. That's why they come with no identifying marks as to which one is which.

I tried that but both rings fit in both grooves.

The manual says the ring gaps specs are:

Top ring = 0.20-0.30mm

2nd ring = 0.35-0.50

I stuck the rings in the cylinder and they answered my question.

If there are any marks on the rings, they face up.

Yep...... there was a 'T' on them. :bonk:

... both rings fit in both grooves.

That's changed since the '08, then.
That's changed since the '08, then.

Yup. '10 and later YZ's use a 1.2, 1.2, and 2mm ring set on some aftermaret pistons.

Generally, the top ring is plated on the ring face (chrome, for NiSC composite and Iron bores), and the 2nd ring is usually un-plated but will somtimes have a deposit of Moly in a thin groove in the center of the ring face.

Are you kidding? Guessing on which ring goes where? Good luck! This is why I don't buy used bikes!

I was thinking the exact same thing....:bonk:

Yup. '10 and later YZ's use a 1.2, 1.2, and 2mm ring set on some aftermaret pistons.

Generally, the top ring is plated on the ring face (chrome, for NiSC composite and Iron bores), and the 2nd ring is usually un-plated but will somtimes have a deposit of Moly in a thin groove in the center of the ring face.

I have put them in the right way then.

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