7 replies to this topic
  • arraCODEBLUE

Posted February 20, 2002 - 10:42 PM


What is the biggest big bore they make for the old 426? Who makes it? $? what all MAJOR modifications do you have to make? I don't want to have to make HUGE modifications. The biggest I've found so far is a Wiseco 450cc kit. was wanting like a 500......

  • MN_Kevin

Posted February 20, 2002 - 11:16 AM



  • Jon_Escombe

Posted February 20, 2002 - 03:10 PM


The biggest piston I've found is a 98mm JE (453cc). It's a special part made from a TL1000 blank, and a bit more of a pain to install than the regular 97mm.

You can also increase the stroke by 4mm, which will give you a max of 484cc. However, rod life becomes a significant factor...

HTH, JonE.

  • arraCODEBLUE

Posted February 20, 2002 - 03:19 PM


Know anyplace that does that modification?

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  • Jon_Escombe

Posted February 20, 2002 - 03:41 PM


I'm in the UK, afraid I don't have any suggestions for getting the parts in the US.

Sadly the British distributor (Phil Allen) passed away a couple of weeks ago, but you could try this German site for info... www.bergos.de


[ February 20, 2002: Message edited by: Jon Escombe ]

  • yz454

Posted February 20, 2002 - 08:42 PM


Change the rod to something else I did. The yamaha needs more stroke and a longer rod.

  • John_Lorenz

Posted February 21, 2002 - 05:23 AM


This guy proved his worth to me many time in the past for Honda strokers. Back in the hayday of XL-250 and XL-350's these were the stuff. The guy does great work. Cant vouch for the 440 yz stroker kit though

  • Ga426owner

Posted February 21, 2002 - 06:58 AM


Be careful, the biggest baddest will also give you the shortest lifespan as others have attempted.
The 450 kit seems to hold up real well.

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