I'm having the same problem! I've just installed a LRD full pipe, airbox mod with no lid, and jetting. It's the first time ever jetting for me. It only runs with my thumb on the throttle, and the plug is dark black. LRD suggested a 50 pilot jet, which I've installed, and I have a 175 main jet. The kit also came with a new needle, which is in the #4 slot.
Are these jets way to big?? What exactly does the pilot jet do vs. what the main jet does.
Forgive me for my lack of knowledge, but any help would be great!

Colin

 

Psuperman112, the Dynojet numbers are not the same as stock Keihin numbers so you can't compare your 150 to the 170, 175, and 180 mentioned here.


Abaran, did YOU try adjusting your idle ****? Where is your fuel screw set at. A 50 pilot sounds quite big so the fuel screw should probably only be about 1 1/2 turns out tops (but this is just a guess).

 

I know dyno jets run smaller than mikuni, don't know how they compare to keihin. i.e. a 165 DJ is a 150 mikuni. The main jet controls your upper rpm range mostly, and the pilot controls your lower. When I did my friends yfz, full gyt-r pipe, it was 165GYT-Rm, 42GYT-Rp, 3turns out, 4th clip, and still wasn't dead on, but any other minor adjustment threw it way off.

 

gytr 4th clip , 172 main, 3 turns out, and go have a blast!

 

Make sure you follow DynoJets instructions exactly. I have a 2001 Raptor, with a full FMF exhaust, and i installed a DynoJet kit on it. It works like a champ. I got way tired of trial and error.

 

I changed my main jet to a 172(down from a 175), and set my air mixture screw out 1.5 turns and it's running great!! Thanks for the tips.

Colin