400EX spark plug choice for 13:1 race motor?

[shockwave67]

I have a 13-1 je piston,ported head,.080 over 426 with fcr carb.dmc pipe and race cam wb track.
what plug for this high compression? Colder than stock right?

[papaw]

i've heard that if you run race fuel for anything run a cooler plug and gap the s*#! out of it.i run 110 and gap my cooler plug very big.......

[NVR2L8]

I have a 416 with a JE 10.8:1 piston, an XR400 cam, FCR carb, FMF Power Core IV Q silencer, and for these mods run a 50/50 mix of 111 race gas and unleaded premium. After running this combo for a few months now, so far I've had good luck with the stock plug. I learned a while ago that changing to a cooler or hotter plug won't make a huge difference in the performance or the running temperature of the motor...instead the heat range of a plug determines it's ability to control detonation and keep itself clean. If you notice the plug is constantly fouling then go to the next size hotter plug...if you're running at constant high rpm's and/or are having detonation problems, then go to the next size cooler plug.

BTW, I have a copy of a message a guy posted at the Yahoo 400EX group that explains it pretty well. Let me know if you want it, and I'll email it to you.

[papaw]

yeah i'm always interested in unread info.for myself,gives me something to do at work..hehe...em-mail me at papaw400@yahoo.com
thanks alot