6 replies to this topic
  • jimbob69

Posted August 25, 2006 - 03:15 PM


Can a stock 400 cylinder be bored to 97mm, then ran with 426 rod?

Im doing a 444 build up this winter and i wanna know if i need to get a 426 jug to be bored or if my 400 jug will go that far.

thanks, ~jim~

  • jimbob69

Posted August 25, 2006 - 07:18 PM


i take it nobody has a clue?

  • GONE1445

Posted August 25, 2006 - 08:49 PM


I think the 400 and 426 jug are the same just a little bigger bore but that is a guess

they make a 444 big bore kit for the 426 here is the site http://www.lukesraci...uksr/yz426f.htm

if the 426 jug will bolt right up to the 400 bottom I would go with that

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  • quailboy

Posted August 25, 2006 - 08:53 PM


i would go with the 426 it wont need to be bored as much so it will hold up better. i've heard of people boring them to much and putting holes in the cylinder wall.

  • jimbob69

Posted August 26, 2006 - 03:05 AM


Does anyone know how thin is too thin, i mean water jacket inner face to the inner cylinder wall, it MAY be able to be measured. Does anyone have a 400 and 426 jug side by side to see if they are basically the same casting?

i mean we are only talkin 5mm bigger, big in the boring cylinder scheme, but its not THAT much material, is there an extra 2.5mm to spare per side?

I NEED to find this out cause i dont wanna spend another 200 bucks to get a 426 cylinder that im just gonna bore if my 400 cylinder will go that big.

If not would it seem reasonable to put a 426 steel sleeve in it then bore that to 97mm?

  • DigilubeJay

Posted August 26, 2006 - 06:32 AM


You need a 426 jug.

You will be very, very pleased with the results if you have a reliable tuner build it.
Install the Kibblewhite valves and springs and the set-up will last and last.

  • jimbob69

Posted August 26, 2006 - 11:27 PM


I couldnt let another person build it for me, its just the feeling of accomplishment is half of the reason i do builds.

Before i got my bike i did a big bore stroker Blaster when i was 13.
That was a great feeling, and i ran the piss outa it and it never gave up.

i have trust in myself i can build a motor just as good as any builder.
as long as i have the right tools to do it.

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