426/450 comversion

[Racerdude]

Known to the honda rice racers as a frankenstein motor, i was wondering if you could mate a 426 bottom end to a 450 top end. the 5 speed tranny is on my want list, but i also want the increased displacement and the auto decompression and such from the 450 top end. just a silly question of mine again....idle minds are a terrible thing sometimes. thanks for the help

 

[flynbryan]

I believe the engine design was changed to much to just swap out the two motors. I'm not certain as to what your doing w/the bike: ie; Hare Scrambles/ Enduros/ Desert/ or just MX, but if its offroading your going after maybe the WR would be a better choice for you?

 

[Racerdude]

flattrack/tt/super motard is the area im shooting for. i was just looking at the cylinder bolt patterns, which are the same, i didnt know if the rods were different or even interchangeable (like the 450 rod would work on the 426 bottom) thanks

 

[CAL]

Would prob. be cheaper to just go with a 444 kit in a 426 anyway.

http://dirtrider.net/forums3/showthread.php?s=&threadid=72546

 

 

[Racerdude]

yeah but corey...there is no replacement for displacement!! LOL jokin!

 

[CAL]

Originally posted by Racerdude
yeah but corey...there is no replacement for displacement!!

(in the words of Tim Allen)  Arrr Arrr Arrr !!! :thumb:

 

 

[endosports]

Yamaha did not change the cylinder bore size but did increase the stroke to get 450cc.

I believe that too many changes had occurred in the design to swap parts. Like the cam chain tentioners and head stay.

Last time I checked Ty Davis just got the #1 plate in the desert on the 4 speed 450.