250-500cc I have a problem with my WR300 2012 year.

Guys,
I have a problem with cold and hot starts (10-15 kickstarts) and my bike often "kick back" strongly when I am starting it. And I watched rich symptoms. Yesterday, I went fast and when I was 5rd gear and full throttle, my bike is stopped. I think the fuel isn't fired and the plug was dirty.
I think I have a problem with Adjusting the timing(ignition), maybe my bike have advance ignition, I want to "retarding" the ignition.
Perhaps I had a problem with float level ( when my bike side stand my carb is drop) and I reduced the float level of, but the problem repeat.
Carb: Mikuni TMX 38
Main jet - 430
Pilot - 45
Needle - "GAY"
Clip position - 3rd
Slide - 4"
Air screw setting - 2
Elevation (feet) - 0-500 ft.
Please, help me.

HAD THE SAME PROBLEM WITH MY NEW 2011 I KNOCKED MY BRAINS OUT !!! THROW THAT MIKUNI IN THE GARBAGE !!! call JD Jetting or motosportz and get the Keihnin PKW !!!

My friend have WR300 2009, he hasn't this problem with Mikuni. I'm from Ukraine, call JD Jetting or motosportz and get the Keihnin PKW - it's difficult.

Do you try to change the spark advance?

i had no luck with the Mikuni.......... sorry i couldn't help. its not the ignition although it acts like it is....

My guess. Cold start the pilot is too big, I use a 27.5 pilot at 1500 feet above sea level. A 30 pilot would stutter off idle but at 500ft you may be able to use a 30.

Wide open throttle problem is most likely float level too low or needle sticking and running the bowl dry. I modified my bowl plug/well to help with fuel getting to the main jet. I'm not sure how much it helped but my Mikuni runs perfect with nearly the same settings. 430 main, 27.5 pilot GAY needle in 4th notch (one step richer than middle).

The bowl mod is as follows; drill 4 or 5 small holes in bowl plug on land next to the threads so the fuel can fill directly in to the well instead of having to spill over the rim of the bowl.

I agree with the rich pilot theory. My 11 starts like a dream when the pilot is correct........

My friends,
Thanks for yours comments, but how can I comment that my bike often kick back strongly when i starting it? It seems that my bike have advance the ignition.

take off the ignition cover, there should be 2x 8mm bolts holding the stator plate in position when you remove the bolts you can see the timing marks, with the bolts removed (or loose) you can rotate the plate (clockwise advance) most people run3 degrees advance to markings, retarding helps top end rev.

2011 and 2012 have digital ignition...................................

2009-2010 - IGNITION
Capacity discharge electronic start with variable advance.

2012 - IGNITION
Type.. . . . . . . . . . .electronic digital capacitor-discharge
type, with variable advance

I think, that it means an adjustable.

You may be right. I have not messed with mine. I can tell you that mine used to kick back and be a bitch to start untill I lowered my pilot and got the air screw correct......

Guys,
why is this man have a same jet kit and his bike starts and runs great?
WRSteve wrote:
Year & Bike Model = 2011 WR300
Carb = Mikuni
Pipe & Silencer =Stock
Other engine mods = none
Premix ratio & fuel type = 50:1 Maxima 927 91 Octane pump gas
Temperature range (deg F) = 45-70 degrees F
Elevation (feet) = altitude is usually between 500ft and 2500ft
Main jet =420
Pilot jet = 45
Needle = "GAY"
Slide = stock??? it says 5 on it and everyone talks about a number 4 slide
Clip position = 3rd clip
Air screw setting = 1 1/8
wait4me wrote too:My bike seized on this jetting.
Maybe I can't adjust the air screw correct?
My Air screw setting = 2

I can tell you, you have to kick it like you mean it. The only time I get a kick back is if I am in an awkward position (stalled on the side of a hill) and can't get my weight on it.

View: http://www.youtube.com/watch?v=2kZZZNUeJKM

How can I this comment?

I'd bet on a too rich pilot circuit. I'd drop the pilot to a 40 and airscrew at 1.5 as a starting point. My '09 300 was sensitive to pilot jetting about would launch you to the moon if the pilot circuit was too rich.

Murda, maybe you should take one of those ladies from the video with you when you go riding. For being inexperienced they seem to get it lighted off pretty quickly!