Freshen up 2000 YZ 426

Yamaha YZ426F 2000 Brand Hot Cams

46 replies to this topic
  • marv02

Posted December 24, 2012 - 04:31 PM


Transmission showed up today I already installed it and put most of the motor back together including the 3mm big bore piston and jug also.

But still waiting for the Head gasket to show up I am hope this week sometime.

  • jojo1224

Posted December 25, 2012 - 07:46 AM


I would like to see some pictures of the +3mm piston and cylinder.

  • marv02

Posted December 25, 2012 - 02:16 PM


The piston and cylinder already installed looks like any other piston cylinder unless you measure it they all look the same as a stock 95mm set up.

But the piston has 1 compression ring instead of the 2 like the OEM piston has.

I put the stock head gasket over the bore just to see what it looks like no way the stock head gasket will work.

If you look at you'r stock 426 cylinder turn it up side down just and there was no chafering there thats how much bigger is the 3mm more piston going to be.

I would like to see some pictures of the +3mm piston and cylinder.

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  • marv02

Posted January 12, 2013 - 06:19 PM


[color=#000000]Received my custom 98mm head gasket from Cosmetic and finally put the motor back together and it in the frame I going to try to finished up the bike this weekend and get it running.[/color]

[color=#000000]My 426 is now a 453 ported head with a WR transmission.[/color]

[color=#000000]But will Murphies law raise it ugly heads as it normal.[/color]

  • marv02

Posted January 20, 2013 - 05:15 PM


Finished putting My 426 with 3mm big bore kit Wr Transmission and ported head back together and running today I still have to get the Jettting right it lean in the midrange I will rasie the needle and see if that cures this lean issues.

Next it getting the motor fine tuned in.

Next project is send the Supension out to get it revalved.

  • marv02

Posted January 25, 2013 - 07:36 PM


Runs great now get the motor broke in and when a 450 wants mess with the old 426 they be in for one big suprize I will tell them it stock.

  • etuke

Posted January 26, 2013 - 07:01 AM


I think the 426 engine had plenty of power to begin with,if I were to do anything it would be to the frame to lighten it or go newer.The wr trans is a good idea and should be a great improvement for trails and woods.If your engine needed rebuild anyways then why not go bigger.Can you notice a big power increase?Can you compare it to a newer 450?

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