440ex spark knock at idle when engine is cold? help

[Redsand069]

i have an 03 honda 400 ex with the 440 big bore kit, stage 2 cam, rev box. i have to replace the stock carb because it was leaking gas. i went with the edelbrock 450 atv carb. only problem im having is a noise at idle when egine temp is cold. it sounds like to me a pinging/knock noise, when i give it throttle, it goes away. could it be spark knock? it also doesnt seem to want to idle very well until engine temp is warm. ive tried putting a colder spark plug in and same thing. i know it could be a octane problem, but i have no where close to try and get higher than 93. can spark knock happen at idle? think the idle mixture is too lean?

[powerbomb400]

Is there any place close that sells dirt track parts or a performence car shop. Alot will sell gas that's a higher octane and that should solve your problem.