Hi,David your right on the money,You get A free prize,send me your address and I will send you out something like two free Vinton O rings.John,the K&B100 on 15% nitro was still not enough nitro.I had to mill A heck of alot off the head to get it to run on no nitro.When you flip the K&B over before milling the engine had nothing but now it has about the same a the Rossi105 does and it runs right now.Take care- Mac