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what would be the reason for using it? The stroke is the same on both motors.
 

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Actually the stroke is not the same. The YFZ crank as a 2mm(?) shorter stroke than the YZ or WR.

The bore is the same.

The YZ crank is supposed to be drop in fit, and allows you to be a full 450cc.
 

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Originally posted by BigAl@Jan 21 2004, 07:33 PM
Actually the stroke is not the same. The YFZ crank as a 2mm(?) shorter stroke than the YZ or WR.

The bore is the same.

The YZ crank is supposed to be drop in fit, and allows you to be a full 450cc.
my bad.... I only checked the YZ specs...
 

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I understand that the wrist pin size on the WR crank is smaller than the YFZ. So if you use this crank you have to use a WR or YZ piston with the smaller wrist pin.

Maybe not a good idea.

Has anyone heard, isn't Yamaha going to come out with a YFZ crank this year to make it a 450 with that extra 2mm stroke?????
 

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I understand that the wrist pin size on the WR crank is smaller than the YFZ. So if you use this crank you have to use a WR or YZ piston with the smaller wrist pin.

Maybe not a good idea.
:stupid I heard the same thing and I agree not a good idea. :nono
 

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There is no reason to do this. You will gain almost no power and will change whee your power comes on becaue of the different stroke.

But the most important thing is that you may lose reliability because of the smaller wrist pin on the YZ/WR pistons.

I did not realize there was such a difference but when I first took my bike apart to install the 13:1 piston that I bought from Vito's I seen it.

They sent me the damn YZ piston, the bores are the same but the wrist pin is so small that you could almost fit a roller bearing in the rod around the wrist pin.

The reason for Yamaha beefing up this area in the quad is because of the extra hook the quad gets therefor putting more stress on the crank and pin area on the piston.
 

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Originally posted by Pahrump@Jan 23 2004, 11:38 AM
The reason for Yamaha beefing up this area in the quad is because of the extra hook the quad gets therefor putting more stress on the crank and pin area on the piston.
that is what i've been told. i thought about doing the same thing until i was told this.

andy
 
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