engine running lean

[ironman99]

i have a vtx1300c. I recently installed mortons down and out pipes with their power cones. I also installed the thunder mgf. tornado air kit. I used a dynojet stage 1 kit and followed the recommended tornado rejetting instructions (210 jet with needle set at 4th from top). I had the bike dyno tested and found the air fuel mixture was running lean (i turned the a/f screw 1.5 out). during accelleration the engine boggs and "pop" when the throttle is let up. does anyone have any suggestions and/or recommendations on how I could tune it so the bike runs "clean". I am new at this.....

[Charlie D]

read the sticky on the carb tune, it will give you a good direction to go.

http://www.vtxcafe.com/showthread.php?t=1914

[ironman99]

thanks i followed it today. That Air fuel screw is a B***ch to get to. I am also going to e-mail thunder mfg. to see what they recommend. Does anyone have an idea on what effects humidity and tempurature has on rejetting.

[Scar]

thanks i followed it today. That Air fuel screw is a B***ch to get to. I am also going to e-mail thunder mfg. to see what they recommend. Does anyone have an idea on what effects humidity and tempurature has on rejetting.

High humidity and high air temps will make the bike run fatter (rich) if it was tuned under "normal" conditions.

Cool/dry air is more dense (with oxygen molecules) and the bike will run better if tuned for that..

Hope that helps -- basically the bike runs on combusted fuel and air.. the more air the better -- High temps has less dense air and therefore less oxygen... humidity (water in the air) takes up space that oxygen could be occupying and therefore has the same effect -- hope that wasn't too simple??

[JMike]

Scar,

You are a gentleman and a physicist!

Rock On!:cheers:

Mike

[Retro Rich]

Curious if you got it running right with that DJ kit; if you haven't yet, make sure you trimmed the "tit" on the needle holder cap if you're using that DJ needle--otherwise, it will bind and not move freely. Your A/F will be way lean at 1&1/2 turns as well with that set-up. 2&1/2 would be the minimum you'd need running that DJ stage III kit. Anything past 3 turns IMHO you need to "jet up" accordingly.

[larryvtx]

I'm no carb expert but read somewhere that you can be anywhere from 1.5 turns out to 4 turns on the a/f screw and be o.k. anything less or more you need to do a different main jet.