Ive asked this question before but I found out that not only is my 4 wheeler gonna get bored .20 over but he is also putting 9:1 pistons instead of the stock 8:1. Will that make a diference at all? Anywhere? The guy doin it said it would make it a little bit faster.

 

I think you're gonna get mainly low/mid range improvement. bigger bore (minimal tough) and higher compression help mostly lowend.

 

There is NO downside to compression, it makes more power EVERYWHERE! If you have the gas avalable to run higher compression, then do it! You shouldnt have to run anything higher than 93 octane with just 9.0:1. You may want to try a 10:1 piston, you could still get away with 93 octane and it will make a good bit more power.

 

What about a break in period for the new pistons? How long is it? Thanks a lot for the help

 

I know that for 2 strokes, at least one tank being very gentle on the throttle, then one other tank being careful not to overrevv, and then WOT. On 4 strokes though, I don't have that much experience.
There are also different breaking in techniques all as boring as hell.

 

I believe the stock compression ratio for a Warrior is 9.2:1 the next step up is 10.25:1 with a Wiseco. The 10.25 will run fine with 92 octane super. You will see all around improvement in power with a compression increase.

 

Don't misunderstand what the guys are saying though...they are right..the higher compression will make a bit more power over the entire spread. (better throttle response...maybe faster acceleration)...But do not expect to gain any more top speed. You'll have to mess with the gearing for that.You may get there quicker.
With the higher compression..you may be able to pull a taller gear a bit easier.
There is alot involved...I think that's why your mechanic told you not to expect a ton of improvement.Depending on cams...timing...pipe...gears..jetting..air flow. You will see different results.