i was just woundering what piston this was!?? is it the .040 or is it the .020?? i was thinking about boring my biek out .040 what do u guys think abotu that!

 

Sorry forgot to ask! Woudl i need to run race gas??

 

What do you mean what piston it this?? It could be many different pistons.

When people run race gas it all depends on the Port design, spark plug location and engine load.. NOT just compression ratio. The octane rating means when it ignites under how much pressure. Fuel ignites mainly under pressure and only uses the plug to keep it going. To low of octane in a higher compression motor means the fuel won't ignite fast enough causing pre ignition or (ping sound) this can damage your engine overtime so it's important to choose the correct octane rating.
To high of an octane will cause the engine to run rich. To high of octane will cause a loss in HP, because the flame won't keep up and your engine will sound sluggish and it will stay that way untill you change fuel.

Here's what I've learned over the years being around racers and the drag strip

89+ (pump gas) you can run up to: 10:1
92-94 (premium) is good till: 11.5:1
once you get over 12:1 you NEED race gas run premium and it will be fine

 

Sorry what i meant to ask was! Witch piston do u think i shoudl get????