400ex 11:1 actual compresion??

[backwoods 400ex]

Im looking at a high compresion pistion for my 400ex and i seen wiesco is 11:1 and JE is 10.5:1. id rather run the JE but i want as close to 11:1 compresiion as i can what would be the best option?? or is CP closer to 11:1?? THANKS

[CJM]

It all really depends on the gaskets you run. Im running cometics and imho they are better than stock and work very well.

Im running an 11:1, never tested it exactly-what I can tell you is I like it alot-but if I had to do it all over again I would buy a 10:1 and get forum member wheelies custom 3 degree timing key. You get the throttle response with the key and the compression bump with the piston.

Im happy with what I got, but always wonder what it would be like on the other side lol.

[Thumpin]

JE and Wiseco pistons are very close looking pistons and are hard to tell the two 11:1 pistons apart. So with that said Je advertises accual compression with stock EX gaskets, Wiseco advertises the average bore size compression. XR bike gaskets are .2 compression higher. Bore size will change compression ratio also. Go to the JE website and check out the changes bore size makes.

So bore to 87mm, 416cc and use XR gaskets with a JE or Wiseco 10.8:1 piston and you will be very close to a true 11:1 compression!