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bluebike1999

do i need a 426 crank to increase cc's

6 posts in this topic

maybe asking the question a different way may help, but i'm trying to figure out whether just changing the rod and piston from a 400 to a 426 will alter the cc's.

the cc increase isnt as important as the extra strength gained in the small end off the rod, but given the pistons are the same diameter, the cc increase must come from the stroke? yes?

i think this is a basic physics question, but hope that someone out there can help.

Thanks

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thanks premo

it must have been atypo on the site iwas looking at, at least i hope it is.

i've got some parts on the way and i thought i may have stuffed up.

should know soon

thanks

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If I was upgrading my 400 to a 426 I would change out the piston, cylinder, and connecting rod with OEM parts. The 400 piston uses a smaller diameter piston pin than the 426 piston. The rods are the same length, just the piston pin hole is larger on the 426. Upgrading to the 426 connecting rod will also increase reliability. Here's a link with a detailed parts breakdown.

http://www.powroll.com/P_YAMAHA_YZFWR426F.htm

The cheapest place I have found for OEM Yamaha parts is here.

http://oem.thumpertalk.com/default.aspx

I'm pretty sure that Wiseco use to sell aftermarket 95mm(426) pistons for the 400, but people were having rod failures in high time motors. The largest piston Wiseco sells for the 98-99 400 is a 94mm. I was planning on doing the same upgrade that your doing to my 98 400, until I found a near new 02 426 dirt cheap. To bad the used dirtbike market in Australia seems to be much more expensive than here in the states.

Good luck :thumbsup:

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yep, thanks for that. i have already ordered 426 piston, rod, rings and cam chain and some more stuff and its all genuine yamaha stuff.

am getting it direct from Japan at about half the cost of sourcing parts locally, eg head gasket locally 78-84 bucks,, direct $35

thanks for your help.

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what you do to the top you have to do to the bottom i.e if you put more powerful top end in it may blow the bottom end up with too much power yamaha learned this when they started producing raptor 660's

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