WR 450 BIG BORE KIT TO 500



10 replies to this topic
  • SEB416

Posted January 23, 2004 - 09:02 AM

#1

Anyone knows if there's any on the market?

thanks guys

  • PowerFiend

Posted January 23, 2004 - 10:28 AM

#2

You can get a 2mm overbore to make it a 472cc, don't know of anyone making them a 500 yet.

  • Indy_WR450

Posted January 23, 2004 - 01:03 PM

#3

Dirt Bike magazine did a WR470 kit article and test last year and loved the results. I just cant remember the issue. I will have to dig for it.

  • captain_S

Posted January 23, 2004 - 01:52 PM

#4

I do know that yamaha has them (yz) :)

  • mtrablue

Posted January 23, 2004 - 02:40 PM

#5

july, 2003 dirt bike mag. thumper racing did the set up for the article. it uses a 2mm over bore wiseco piston. also check; www.eric-gorr.com
he's been doing this kind of stuff for a long time.

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  • SFO

Posted January 23, 2004 - 03:00 PM

#6

http://www.eric-gorr...fourstroke.html

  • MrBlahh

Posted January 23, 2004 - 03:29 PM

#7

Anybody know if the WR450 jug is compatable with the WR400 head? Or is this a possible swap with a complete top end?

  • PowerFiend

Posted January 26, 2004 - 03:48 PM

#8

Anybody know if the WR450 jug is compatable with the WR400 head? Or is this a possible swap with a complete top end?


??? If you are wanting the larger bore (95mm), I believe you should be looking for a 426 cylinder not a 450(The bores of the 426 and 450 are the same). The 450 is all different and is not compatible.

  • MrBlahh

Posted January 26, 2004 - 05:23 PM

#9

Right now I have a 426 jug on a 98wr400

it's bored out 2mm, so it's running 444cc I believe, 13:1

but if I want to go 500, can this jug be bored out 4mm? I thought that would be pushing it.

  • PowerFiend

Posted January 28, 2004 - 11:03 AM

#10

Right now I have a 426 jug on a 98wr400

it's bored out 2mm, so it's running 444cc I believe, 13:1

but if I want to go 500, can this jug be bored out 4mm? I thought that would be pushing it.


I don't think 4mm over is possible. I think I saw a 3mm over and they were having a hard time keeping head gaskets in it. You can go with a Powroll 2mm stroker for like a 469cc motor, YZDAD1 (SP???) did this. It requires a custom thicker base gasket to run with aftermarket and non modified OEM pistons. Talk to Cometic for the gasket, should be roughly 1mm thicker.

The 450 gets its extra CC's from a longer stroke, not a bigger cylinder bore. :)

  • PowerFiend

Posted January 28, 2004 - 11:06 AM

#11

Right now I have a 426 jug on a 98wr400

it's bored out 2mm, so it's running 444cc I believe, 13:1

but if I want to go 500, can this jug be bored out 4mm? I thought that would be pushing it.


I don't think 4mm over is possible. I think I saw a 3mm over and they were having a hard time keeping head gaskets in it. You can go with a Powroll 2mm stroker for like a 469cc motor, YZDAD1 (SP???) did this. It requires a custom thicker base gasket to run with aftermarket and non modified OEM pistons. Talk to Cometic for the gasket, should be roughly 1mm thicker.

The 450 gets its extra CC's from a longer stroke, not a bigger cylinder bore. :)


And doing this would put you within 3cc of an overbored 450. If you are looking for more, some custom head work and some hotcams may be in order. :D




 
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