Compression Ratio's 11:1 or 13:1?
 

For a 686 raptor, would a 13:1 comp piston out do the 11:1 by a few horses? I am just a little hesitant on which compression piston to get, because cam 2 up here is 5.50 a gallon, and i know with a 13:1 i will need that. 11:1 i can run 93, but im tryin to get the most HP out of the ol rap. Any input at all is appriciated.---Rider1169

Compression Ratio's 11:1 or 13:1?
 

Yes with all else remaining the same you would probably see a 2 or 3 HP gain when going from 11:1 to 13:1.I have a 690 that had 11:1 and now it is 12.5:1 and i can tell the difference but as you said you should fac tor in the cost of fuel and remember that 13:1 compression will be much harder on your starter.If i used my raptor for casual riding or just occasionally did some drag racing i would stick with 11:1.

Compression Ratio's 11:1 or 13:1?
 

Right, i dont ride too awfly much anymore, and when i do its just racing around and fast trail riding. I know 13:1 might be overkill, but i just want to have a pretty sick bike thats fun when i go out and do ride.

Compression Ratio's 11:1 or 13:1?
 

If I may...I would suggest going to a 10mm head bolt if you go 13 to 1.

Compression Ratio's 11:1 or 13:1?
 

That is also helpful info, thanks for that bolt suggestion.