I rejetted with mikuni jets 165,170 it runs good,needle 3rd from top(middle).I hauled up the road about 1/2 mile and back ran good.checked the plug it looks brand new.so im thinking it must be lean.I put my lid and snorkel back on(lid cut in half)and rode it up the street.It ran the same.I put a couple strips of duct tape over the box to restrict more air and reved it and it was loading up.I rode it up the street and it bogged took off one strip of duct tape and it bogged took off more tape still bogged,took off all tape runs sweet(with hacked snorkle and half lid) took off lid and snorkle runs sweet.Since the plug was white with no lid,I put in a new plug and took it for 20 min ride with hacked snorkle and half lid.It ran good.Got home checked the plug still looks brand new .WTF.I shouldnt have to jet higher with just exhuast,k&n,and no/lid should I.I live at 3,250 ft elev. My screws are 3 turns out.Any info appreciated

 

Try the 4th clip with a 27 pilot and 2and a half +/- turns out.

 

When you are doing these plug checks are you running full throttle (on the mains primarily), or are you cruising (on the needles)? We need to know what circuit you are primarily on to give an accurate recommendation. If it's the needles richen them until the engine balks, then back off a clip position and you should be set.

 

yeah I was reving it pretty hard on the way up the trail bogging back home.Pulled in the garage and reved it to full throttle a couple times about 1 1/2 seconds each rev killed it then checked plug.It looked pretty much new a little powdery whiteish,grey on metal strip above insulator.Insulator white,top thread kinda brown.By the way bike ran better than ever.

 

yeah I moved the clips to the fourth slot it didnt pull as hard didnt seem to want to rev out.guess im going back to the third slot.checked the plug after full throttle up and down road with clip in fourth slot from top still white.Im about to say screw it and just go with what it runs best at.

 

So did you go from the 3rd to 4th slot measuring from the top of the needle or the bottom? The needle clip location means very little when the throttle is wide open. Cruising at lower speeds about half throttle will tell you what the needles are doing. While cruising and adding the choke...does it run better or worse? The choke richens the mixture up a bit. When you are wide open apply the choke and this will indicate if the bike wants more fuel. Apply choke.....bike runs better = needs larger mains.
Gary

 

yeah thanks,I measure needle slots from the top 1 to the bottom 5.I had it jetted with dynos 148/150 it ran good but backfired on decel.I got 25 pilots and fixed the backfires.It ran great but the plugs were like brand new so I wanted to jet up but kit didnt have any bigger jets no local dealer carried dyno jets so went with mikunis.Replaced stock needles and springs jetted it 155/160 middle clip ran like crap.Jetted at 165/170 runs like a champ but plugs were white.Maybe if I just go 170/175 3rd clip it will solve the lean plug problem and still pull.Anyone else with full exhaust,k&n pro flow,using mikuni jets 170/175.I love jetting!

 

i cut & pasted this hope it helps!!!! on how to read a plug most people read them wrong



TO READ PLUGS PROPERLY YOU WILL NEED A 10x ILLUMINATED MAGNIFYING GLASS

1,2,3. This is how it's done!

1. You set your heat range from the ground strap (this is the piece closest to the piston).

2. You do all the plug readings for jetting from the base ring (the base ring is what the ground strap is welded to at the end of the threads)

3. You determine detonation and timing issues from the porcelain (The porcelain shows preignition/detonation, it will not accurately determine jetting / air/fuel ratios).

DO NOT BASE JETTING DECISIONS ON THE PORCELAIN COLOR.

1. How to determining plug heat range:

The ground strap is your window to getting this right. If the "color" of the ground strap "changes" too close to the ground-strap's end (the end opposite of the base ring), then the heat range is "too-cold", (heat transfer is to quick to the base ring)
If the "color" of the strap changes near where it is welded to the base-ring, then it means that the plug heat-range is "too hot" (heat transfer to the base ring is to slow causing the deposits to be burned off the strap completely) The strap at this point could start working like a "glow-plug", probably resulting in pre-ignition/and/or detonation. The properly set heat range is when the "color" is at the half-way point on the strap.

2. Reading the base ring to determine jetting:

The base ring "color" is very close to the color of the piston crown and is used to determine the jetting. You're looking for the soot color to be a nice light to medium brown. If the color doesn't go all the way around the base ring (at least one full thread turn on the plug) or the color is white-ish, it is too lean. If the color goes all the way around, but there is a spotting of heavy dry soot on the top of the color, you are too rich. (TWO STROKE JETTING WILL BE A LITTLE WETTER LOOKING AND DARKER THAN A FOUR STROKE)

3. Read the porcelain to determine detonation / preignition:

The first signs of detonation / preignition will be seen on the porcelain down in the plug, It shows up as tiny black or shinny specks of aluminum. Also Look very close around the center electrode where the porcelain intersects, this will appear to be melting between the insulator and the electrode.

Detonation is caused by the air/fuel mixture exploding rather then burning. This gives off a sound (a knock). This sound is the result of a shock wave. This wave disrupts the boundary layer of cooler gasses that cover the internal parts of the combustion chamber. This causes a very rapid rise in pressure and temperature. The results are holes in the top or sides of the pistons, blown head gaskets, or broken rods. This can also shock the rings from there seal causing oil to form as little spots on the porcelain.