Join Date: Dec 2010
Thanked 101 Times in 61 Posts
I have seen the special "short" plugs that some KTM's spec go for almost $40 at a dealership. I believe that they were special, only because of fitment issues. The fuel tanks on these bikes hangs down very low, but a regular plug will fit.
I have also witnessed, many times, the precious metal plugs getting fouled with what looks like a tiny hair. I am not sure what this is, but it looks like a thin hair, or wire, that spans across the electrode to the ground strap. Once this happens, the plug will often refuse to fire again. These plugs seem to have an especially short life span when used in 2-stroke engines burning castor. Some MX bikes specify these plugs as OEM, but a normal plug will work just fine.
A normal "standard" NGK "ES" plug will cost around $2.50 these days, and should last for at least a year in a good working motor.
The Champion plugs that you see in Wal-Mart, or other stores, will work, but if you look closely at them, you will see many imperfections and quality issues that make me shy away from them. The electrode tip often looks like it was just "broken off" and not cut with any precision.
I have never realized any performance gain with the Splitfire, "E" plugs, or even the $8 precious metal plugs. The same goes for any of the "spark enhancers" that are pretty much just large capacitors that install in your HV lead. There is a newer one out now, but they all meet the same fate - they just fade into oblivion - for good reason.
2011 Grizzly 450 EPS
2006 Kodiak 450i
2004 KDX200 Dual Sport
1999 Ninjette 250