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SNO_DAY
08-25-2009, 08:52 PM
can the weather effect carb performance? I have been having a lot of trouble with my 1999 honda 400ex. I have cleaned and adjusted my carb 10 times and even took it to the dealer for a professional tune-up but with no luck. it keeps bogging down and fouling the plug. the weather here has been very hot, high 80 temps and 90 percent humidity. but in the last week after hurricane Bill the weather has gotten cooler and the humidity has dropped. and what do you know the bike seems to be working better every day. Is this possible or did Bill blow away my good sense?... by the way the carb has had a dyno-jet kit installed and has a pipe and k&n filter.
matt14c
08-25-2009, 09:06 PM
Yes temperature can affect the carb but unless you had it jetted properly for freezing cold you should be going to the extreme of fouling plugs.

Go here then go to How To Rejet

http://www.jetsrus.com/main_page.htm

This site has tons of good info for getting the carb dialed in.
Snipe
08-25-2009, 10:09 PM
Temp has a huge play in jetting. Colder weather temp air is thinner and will usually require a bigger jet to keep you running right. Warmer weather is different. Humidity plays a role as well as barametric pressure.

I have mine jetted for summer time riding 80's most the time the other day god a few day rain shower temps down in the mid 70's when I started it up it was smokin a bit until it warmed up. Jets and temp go together like peanut butter and jelly.
F-16Guy
08-26-2009, 07:09 AM
If your carb is jetted correctly (which it's obviously not), you should be able to ride through a pretty wide range of temps. I'm willing to bet that you installed the stage 2 jetting outlined in the Dyno Jet instructions. Unless you have a high-compression piston, cam, exhaust, and filter, you need to run the stage 1 jetting per the instructions. Don't deviate. Just follow the stage 1 instructions for your altitude and mods. It should be:

-- DJ needle with clip in middle slot

-- 142 or 146 DJ main jet (probably a 142 if you have a stock filter)

You should also buy and install a 42 pilot jet and set your fuel screw at about 2 1/4 turns out. If you don't do that, just set your fuel screw to 3.5 turns out per Dyno Jet.