Wiseco piston comp. ratio for ATC 200x

[dansvan]

Hello all. Wiseco advertises it's replacement pistons for the 85 and down 200x's at 10.25 to 1. This is a bump up over the factory advertised compression ratio. Is this true? Are they really a compression bump and not a direct replacement? I do want the extra compression.

Also, I see many other high compression pistons listed for the same bore and stroke size as the 250sx, but not for that machine specifically. Has anyone compared one listed for another Honda 250cc with the same bore and stroke side by side with a 250sx piston?

[thefox]

Yes the 10.25:1 is a little higher compression then the factory spec. (factory is 9.6:1). They also sell a 12:1 compression piston but you will most likely have to run race fuel (110 octane or better) with that one. The 10.25:1 piston is what I would go with if I needed to replace the piston.

I can't offer much help with the 250sx, hopefully someone else will.

[DixiePlowboy]

When I built my last '84 X several years ago, my overbore(can't remember what size) had to be a 12.5:1. They didn't offer that size in 10:1. I used 100 octane aviation fuel with no problems.....other than the sore right foot I quickly developed cranking it