07 missing but not cdi studder help

Weather is warming up and my bike seems to be missing a little more lately. I installed a JD jet kit and went with there specs and it seemed to work fine in colder weather but now it has a little miss at a quarter throttle. I don't think its the normal WR stutter because it happens when when opening up the throttle slowly. As soon as i hit about quarter throttle the bike starts missing till I pass that throttle position. Elevation is sea level with a 48 pilot jet, 170 main jet, JD Red needle on the 5th clip position. Bike has a YZ header, Lexx MXE silencer and Hot Cams. I emailed JD jetting with the mods done to the bike and that is the jetting they told me to run. What should i do i'm thinking it may be the needle to rich because my license plate is a little sooty from the exhaust pipe.

I had to re-jet mine 3 times before I was happy. In fact my old 426 took numerous tries at jetting but well worth every minute in the end. Nothing like a well jetted bike.

Try your blue needle, same clip poistion

Try one clip leaner on the red needle, #4 from the top.

Blue #3 is about the same as red #5 too.

It certainly sounds rich.

Try your blue needle, same clip poistion

why would you want to go a whole crap load richer? :thumbsup:

Well here is a pic of my plug color and the soot on my license plate. What do you think?

DSCF0234.jpg

DSCF0235.jpg

DSCF0238.jpg

Rich. Hotter temps increase the amount of available fuel due to the air molecules being less dense, effectively richening the mixture. Air molecules when cold are packed together very closely, creating a lean condition if no extra fuel is added. So when you jetted you jetted for the cold condition....now its considerably hotter, thus a rejet may be in order. Sounds like your needle...like suggested move to Red 4. Hit the gas WOT too and see how it feels...possible you can go down on your main....or maybe its fine....but WOT will tell you yes or no. Plug looks rich. You want to LEAN it out...not richen it up in the summer.

Well here is a pic of my plug color and the soot on my license plate. What do you think?
unless that is a brand new plug, you're wasting your time! That plug looks old. very old!

Did you get it sorted out?

Tried the JD Red needle in the 4th clip position with a new plug and took the bike for a little ride. Checked the plug and it looked a tad bit to whitish/grayish for my liking so i moved it back to the 5th clip position. Stutter actually seemed to be a little worse along with a little backfire. I'm thinking it may be lean on my pilot? Happens when i accelerate lightly and hit the 1/4 throttle position and goes away after the throttle is moved passed that position.

Pilot is only gopt idle. Straight diamter of the needle is for just off of idel to about 1/4, taper/length/clip position is for 1/4 to just below WOT.

Pilot is easy enough to swap. What abou ur fuel screw u played with it yet? Also for giggles disconnect the tps and ride it before swapping pilots to see if it's diff

Haven't tried the fuel screw yet going to try that this week. I will also try disconnecting the tps.

Tried the JD Red needle in the 4th clip position with a new plug and took the bike for a little ride. Checked the plug and it looked a tad bit to whitish/grayish for my liking so i moved it back to the 5th clip position. Stutter actually seemed to be a little worse along with a little backfire. I'm thinking it may be lean on my pilot? Happens when i accelerate lightly and hit the 1/4 throttle position and goes away after the throttle is moved passed that position.

For plug reading, I find it is very hard with out leaded fuel. You got to hold it at the one throttle position for ages (riding it), then stop the engine straight away. I don't bother anymore, I just go on feel. Not like the good old 2 bangers.....

Have you got an adjustable fuel screw? If not, they are a very worthy investment for a couple of bucks.

To find your pilot jet size (usually 48), raise your idle speed to like a fast idle. Adjust your fuel screw in then out till you find the point of max rpms. It is real noticeable. This is 'setting your fuel screw'. If this is more than 2 1/2 turns out, go to a bigger pilot jet. :thumbsup:

When jetting a bike, I find it easiest to set the pilot jet first, then main jet, then needle. :lol:

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!


Register a new account

Sign in

Already have an account? Sign in here.


Sign In Now