alright i am new to this sight but hope someone can give me some ideas. I have a 1999 yamaha srx. i blew a rod off the crank so i bought a 2001 srx motor. slapped it in, put my carbs powervalves etc on it n i just cant get it to pull more than 7000 rpm. i did change the jets due to each motor requires different jets on opposite sides off the motor. i also when i got it had to use my stator from my 1999 due to plugs from stator being different. now yesturday i went on long poker run with long straight aways n sled seemed after being held wide open like it was starving for gas. then after bout 80 miles melted a plug. I mean melted like pre detonation pic in repair manual. now i have no idea what is going on with this thing. do i need cdi box from 2001 motor or doesnt it matter? jets are 150 on pto, 148 in the other two. power valves are perfect, air box is gutted with bender pipes n silencer. wy otheer motor would make this thing scream. i rode it for 8000 miles till it blew rod. any help would be appreciated