I have a TRX400x and a strange lifelong passion for spark plugs Really, as a kid I drew cartoons featuring Champion spark plugs as super heros. ANYHOW, I plunked down $5.11 to have fun with the Autolite XS4163DP Xtreme Sport Spark Plug and, boy howdy, did this ball of fire wake up my Honda! Noticed marked improvement in idle (smoother), warm up time (needs next to no choke at start) and throttle response (quicker). Super worth it!!

 

I use the NGK variant in my boy's quad...easy starting, no fouling...

 

Years ago, I put one of the multi pronged plugs in my quad.

I immediately noticed I should have saved my money and stuck with the ngk's I'd been using.

 

Same thing on this plug that the feds got on to the makers about false advertisement. Junk..

 

I've had best results with NGK spark plugs too.

 

I think the split fire is what I tried.

 

Honda old model Rubicon uses Iridium plugs, no idea why. We have a trade in 250 Recon that burns a lot of oil, and had coked it's plug last week, so out of interest, I stuck a used Rubicon plug in it, much better starting and idling. It has gone out as a courtesy bike. Lets see how the plug is after a couple of weeks in a heavy smoker.