How does my spark plug look?

[j0sh]

Just got back into riding and I have never really done much with them in the past. So far I had put a 42 pilot and 150 main jet and Uni filter. I later added a 450r slip on and it seemed that it was pretty lean. so I upped the main to a 170 and this is where im at. Does it look ok?

http://i27.photobucket.com/albums/c169/element_dc5/400ex/photo12.jpg

[bkb88]

Depending on the temp. in your area you should be in the #150-158 range on your main jet. A #170 may run okay but it is probably too large for only a slip-on. You should look in the popular 400ex thread section and read up on how to perform a "plug chop" to properly determine where you are on your jetting placement.

[3400ben]

This will help. http://www.atvriders.com/articles/sparkplug.html

[j0sh]

Put a 160 main and re adjusted the fuel screw to 2.5 turns out and took air box lid off. WOW! Runs strong and doesn't bog anymore under light throttle. It is dark outside and the flashlight was really making the plug look white in pics, but I think I'm good now.

http://i27.photobucket.com/albums/c169/element_dc5/400ex/IMG_0450.jpg

[mlabarca240]

That looks loads better! You may even be able to go down one more size, but if it runs good then I wouldnt mess with it anymore. I rather have my bikes run a little rich than a little lean.

[MtnEX]

Looks good to me.

But remember you really only have to try 2 more jets to have tried them all.... a 155 and a 152.

[j0sh]

This was the first time I ran with the air box lid off. I really like the sound :) Also I have a 158 jet that I may run come summer time if it seems too rich. Thanks for the help