Yaxy Posted May 5, 2004 Report Share Posted May 5, 2004 (edited) I am trying to figure out how to lean out my pilot/needle circuit and still have the bike run properly. My shee has FMF pipes, V-Force reeds, Cool head (21 cc domes) 28 FS Mik and MX port. I run Yamalube 2R, 40 to 1 with 93 Octane at 800 ft. Current jetting is as follows Pilot - 20 (Rich, plugs wet), run 15 sometimes and bike runs beautiful Needle - 5DP39 2nd from leanest position (Plugs a little dark but starting to clear up) Main - 280 probably a bit rich I ran this set up for about 5 or so years and bike runs great at temps from 40 to 90 degrees, NY weather. The only issue I am tying to solve is to reduce the amount of smoke (lean her out) coming out my silencers from idle to 1/2 throttle. I leaned out the needle one more position and it made a great improvement but bike won't idle right. It starts fine but when Idling you can tell it is starving for fuel. Even though throttle response is adequate it is not as crisp as it is with needle clip in 2nd from lean position all other things being equal. Can anyone recommend a Mikuni needle that would lean out my pilot circuit through half throttle yet still have crisp throttle response? I know this is an open question but if anyone knows where i can find some form of needle chart that would be a good place for me to start. I consider myself pretty good at jetting since I have owned it for 14 years so please provide intelligent responses. Carb sync is fine,(cables and idles), new plugs, clean carbs etc... Thanks for your help Chris Edited May 5, 2004 by Chris Yax Quote Link to comment Share on other sites More sharing options...
sredish Posted May 5, 2004 Report Share Posted May 5, 2004 i think it probably has more to do with your premix than your needle setting. You might switch oils to one that has less tendency to smoke, I see your running a 40:1, which is the first thing I thought of, the ratio. The ratio isn't a super rich ratio. I know Holyman runs (and sells) Amsoil @60:1 or something pretty close to that. My Maxima 927 smokes when cold but clears up great after warmed. Leaning the needle to the point of starvation is not a good thing. You might try 2nd or 3rd clip, but leaning your pilot back a little. Try CarbParts.com for some charts on needles and such. Follow the links to Mikuni and on in. Just some thoughts. I'll keep thinking and I'm sure someone smarter will come on in here. Quote Link to comment Share on other sites More sharing options...
Yaxy Posted May 5, 2004 Author Report Share Posted May 5, 2004 (edited) sredish; Thanks for the reply; I think I am going to a 15 pilot and putting the needle clip in the middle slot. This way I will reduce the amount of fuel at idle because my plugs are soaked at a 20 pilot and the needle postion should compensate for any low end loss. The 15 pilot should help reduce the richness to 1/2 open throttle. I will see how this works. IF not I will go back to a 20 pilot and needle clip in 2nd position and live with it till the point where I decide to try a different needle. I also took a look at the site that you suggested. I have the same chart in a Mikuni manual that I have. Thanks for the recommendatio anyway! Chris Edited May 5, 2004 by Chris Yax Quote Link to comment Share on other sites More sharing options...
Banchetta Posted May 6, 2004 Report Share Posted May 6, 2004 Best way I adjust my pilots is to warm it up, let it idle...Punch the throttle to see how fast it revs up and whether it hesitates, stalls out, or sputters....Try this w/ the air screw at .5 turns out, the try it at 2.5 turns out....let me know which way is better... Quote Link to comment Share on other sites More sharing options...
Yaxy Posted May 6, 2004 Author Report Share Posted May 6, 2004 Banchetta; I pick the right pilots similar to what you do. I chug the bike in 1st or 2nd to the point to where it almost want to stall, open up throttle all the way if it goes blahhhhhh I turn in the air screws all the way. If still goes blahhh then I know I have the wrong pilot. When I ran the 15 pilot the bike ran sweet and pretty clean but after a year on a fresh motor I lost a bit on bottom, thus went to a 20 pilot and it was fine. Chris Quote Link to comment Share on other sites More sharing options...
Banchetta Posted May 7, 2004 Report Share Posted May 7, 2004 Try it at an idle, I'm sure you will see more accurate results.It takes the motor a few seconds to adjust to air/fuel mix of different throttle positions, riding it will make it hard to tell between the needle and pilot Quote Link to comment Share on other sites More sharing options...
Yaxy Posted May 8, 2004 Author Report Share Posted May 8, 2004 While doing a bit more analyzing I noticed that I did not have the stock needles in that came with the carbs. Years ago before I put my cool head on I had to use a different taper needle to allow more fuel down low, (5DP7) Per my Mikuni manual the carbs come with 5DP39. I put these back in and seems to be better. Thanks for all your help, I just have to figure out why it is not idling right at this time. I'll tell ya, all these years and still learning!!! Chris Quote Link to comment Share on other sites More sharing options...
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