I just got around to pulling the plug on my raptor.[img]i/expressions/face-icon-small-blush.gif[/img] What I found was not good. Sorry I'll start at the beggining. I installed a FMF powerbomb header, Titanium Silincer, 10.75:1 JE, web cam, Proflow intake with no air box. The jetting is 180/185 mains, stock pilots, 3 turns out on the mixture screws, and dyno jet needles on the 3rd clip. I used this jetting for a safe basis from info that I've found. Well the plug is white/tan (more white than tan) with detonation on the porclin! Would a set up like this need more main? I've inspected the carb boots no intake leak, any other suggestions? One more thing it is still standard bore and the head is stock (no porting). It runs great ,but the plug scares me![img]i/expressions/face-icon-small-confused.gif[/img]

 

just some added info.. if u or anyone needs to know what the colors/ deposits are on plugs and what they mean, go to the local auto parts store and look at the back page of any repair manual. it has pics and descriptions.

 

Your running lean, the plug is white hot, no good! Fix the jets to run richer. Ive heard plugs should be a honey brown, but thats on a 2 stroke...


-nick

 

First, richen the needles until the engine balks (surges or hesitates) and back the needles back a notch....mid range will be set. Next, keep richening the mains 'till the plug is a dark grey color (the needles may have already taken care of this condition if you previously did not do a full throttle plug chop). A richer mixture will help ward detonation off. 1 shade colder plug will decrease cylinder temps....helping the detonation problem as well.