Piston questions

hi guys,


I am rebuilding my 2004 YZ450F.


I bought whole thing I needed, but the Cylinder and Piston kit was for YZ450F.

So Cylinder seated OK, but Piston pin was bigger than the YZ450F. Couldn't go there in piston rod.


I am going to buy a new piston. So any warning for me???


What years and which models' piston and piston pin will fit???


Of course the crank shaft and connecting rod is stock 2004 YZ45F.



please help

Sounds like you were given the wrong piston. As far as I know all piston brands will fit if you have the correct piston.

I would check out wiseco pistons. I use them for all my rebuilds and haven't had one bad piston yet. My most recent rebuild was a xr 500. I put a big 12:1 piston in that pig and no complaints what so ever about their product 3000 miles later.

as my current conclusion after research on GOOGLE; YZ AR are use 18mm pin sized piston, unlike 20mm on YZF. Otherwise, cylinder will fit to each other.

So I can buy any of pistons for YZ and WR with 5 valve seat.


correct me, If it is wrong.

Yes this is correct. But you must watch out for the year. Yamaha may have changed the piston deminsons over the years and ect. So before buying a wr piston make sure it's he same year or same model year span. Just to be safe I would recommend getting just a yz450f piston and play it safe.

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