YZ450F compression?

Want to get a new top end and want stock compression does anyone know what that would be for a 2004 YZ450F?

The stock Yamaha is considered to be of very high quality, also Wiseco is a good piston also. I think stock is 12.5:1, but not positive.

You are right about 12.5:1 for the 2004 model. Yamaha lowered it to 12.3:1 for 2006 and 2007.

why did they lower it.

my buddy has a 06 and my 04 hands it the 06 its ass everytime we race.

So his is completely stock, and you drag race, right? :applause: That won't work with my '06.

Try this: ride his bike for 15 minutes, then roll off 3 timed laps. Then compare that with your best three on yours.

See I had an '04 and my '06 at the same time and the '04 seemed weak compared to my '06 when jumping off one to the other.

Yea my buddy has an 06 and it hawls ass he ends up always faster than my 04 must be the 5 speed :applause::lol:

i heard they lowed the compression for less of it midrange hit. :applause: :

You heard wrong. The drop in compression was the byproduct of changes made to the combustion chamber to improve the head. A 0.2:1 drop in compression is inconsequential.

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