Crf 500

Joined
Aug 18, 2001
Messages
66
Likes
0
#1
I have heard some talk and done some searches on making a crf450 into a crf500, actually a 498cc but thats close enough. I know that eric has done this to at least a few engines, and I am looking for an update on how this is developing. Are their any reliability issues with this as compared to the 480 big bore? I know that the yz426 can be made to a 444 and a 13.5:1CR piston can be used with good pump fuel (yea, yea, I know all about it Rich...) What kind of CR can be run in this size of engine, are their any head mods that are REQUIRED, and what will the power dilevery be like if the 500BB is acompanied by head porting and an oversize header/big bore specific exhaust system?
 

EricGorr

Super Power AssClown
Joined
Aug 24, 2000
Messages
708
Likes
1
#2
Hi,

I built a few of these for mx and dirt track use. The big bore seems to be just as reliable as stock. Wiseco now makes a cast cylinder with larger water jackets, but we haven't seen any over heating.

Regarding other things to go with it, I'd suggest the Kibblewhite oversize valves, bore the carb to 42mm, and use a high lift Webcam.
 
Last edited by a moderator:

EricGorr

Super Power AssClown
Joined
Aug 24, 2000
Messages
708
Likes
1
#4
I know there was some dyno charts posted by SFO somewhere here on DRN a few years ago. Maybe Rich has some on file or some simulation data from Virtual 4-Stroke or Dynomation.