WR450 Combination of cylinder head and valve lifter colors

Hi everybody,

I bought for my WR450 2003 an head from 2005 (it is cheaper).

Everything is the same, with small difference. The 2005 has AIS system ports.

The problem is that 2003 and 2004 heads have valve lifters with different colors (mine are blue), but 2005 head have only yellow.

Can someone explain me what is the difference between valve lifter colors and head on WR450?

Which is different in lifters with different colors (blue, yellow, red, black, green)?

Can i use blue colored valve lifters on 2005 head? They fit and move well.

Thanks in advance.

My assumption is that Yamaha uses the color code to correspond with the size of the lifter hole. If I am correct, then I doubt you would be able to use the blue buckets on your '03 head.They might fit, but you don't want them to be able to rock from side to side in the hole, which could cause them to seize or worse. As I've said though, this is just my guess. Anyone else know for sure?

I believe you are correct, the color codes correspond the the sizes of the buckets and the bucket color codes should match the hole codes.

I think also that this is the difference, but i will try to find one yellow lifter, to measure and to be sure 100%.

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