DE-Porting 2-stroke for low end

enigma

Member
Apr 22, 2006
3
0
Here's the question to you 2-stroke techies, I have a 93 WR500 (YZ490 engine) that I want to make into a low-end power monster. This is just a play bike, so max hp is not an issue for me.
Here are mods I have in mind so far:
-Mill off .040-.060 off the bottom of the cylinder to lower all the ports, and open up the combustion chamber to compensate for increased compression (which the 490's need anyway)
-Add length to the header pipe (I have an FMF)
-Replace the std Mikuni with a flat-slide.
-Reed spacer.
-Now the fun part, can the exh port and transfers successfully be made smaller?, maybe by adding a small alum piece to the top of each (they better not come loose!) or adding some kind of epoxy or bondo-glass and reshaping?

Just a thought exercise for now, thanks.
 

kim80y

Member
Feb 3, 2006
4
0
keep the header pipe the same, lenghten the silencer, run light carbon reeds, the reed spacer is hard to fit in with stock carb, and maybe a flywheel weight to tame it a little,dont mill the barrel, just do an Al holley head mod, or the Eric Gorr one, oh and check out my photos...kim80y
 

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