More jetting woes

A month ago my 00 WR400 ran great. I had richened the jetting a little from stock due to colder weather.

Stock jetting was:

165 main

42 pilot

3rd clip on needle

fuel screw 1 1/8 out

1st change was:

168 main

42 pilot

3rd clip on needle

fuel screw 1 3/4 out

Ran really good! Then the weather change.

Since it has gotten a little colder I have tried:

170 main

42 and 45 pilot

3rd and 4th clip needle

fuel screw 1 to 3 turns out.

168 main

42 and 45 pilot

3rd and 4th clip on needle

Fuel screw 1 to 3 turns ou

165 pilot

45 pilot and 42 pilot

3rd and 4th clip on needle

fuel screw 1 to 3 turns out

But it still is really slugish on take off and throughout the whole spectrum. It starts pretty easy after warm up it idles ok then after you ride for about 10 or 15 minutes it goes to crap. Won't idle and when you let of the gas while riding it goes dead it is hard to start back up. When going through the gears it's coughing and sputtering like it is going to kill over any second. I tried to give every setting about 15 or 20 minutes of riding, I was by myself so I could really pay attention to how it was running. But all settings had about the same results. CRAP! After every setting I have checked the plug: sooty around the base of electrode and a little up it but on the horizontal part it is dark grey but no soot, just bare. I live in Reno the elevation is about 4000-5000 feet. Have a White Bros. silencer with stock head pipe, 12 discs. Air box lid removed, stock air filter(clean). Emptied tank of gas thinking maybe bad gas, no such luck. Have maybe I lost my mind and headed in the wrong direction? Should I try a different needle? Any help will be greatly appreciate.

P.S. A guy I met Sat. while broke down says he richened up the main to a 168 other than that the jetting is stock and his runs great. Why is it two identical bikes bought from the same dealership ridden in the same area are so different?

First suggestion - Don't use the 4th clip on your stock needle DRS, it will be too rich while riding. (This would invite plug fouling at sea level let alone 4000ft) Stay in the #3 clip slot.

Also, try about 2 turns with the 45 pilot jet and get a new plug. Make sure the plug wire is in good condition, getting a good spark.

Make sure nothing is clogged in the carb and the accelerator pump is working too.


Originally posted by GRC:

A month ago my 00 WR400 ran great. I had richened the jetting a little from stock due to colder weather.

You could cover the other radiator at least partly. I had similar problems with my 99 bike. Started easily and idled well but didn't run well after a while. I had a 170 mj, dxm (European model) at #4, 48 pj, fs about 1 1/2. When the weather got cold, around zero Celcius, the problems came. After many attempts I came up with settings 175 mj, dxm at #5, 48 pj. I lost the track on fuel screw but won't touch it because now it runs fine. I also covered the left side radiator completely.


if you've done a proper plug 'chop' the bike has run lean/correct on 3/4 or full throttle. it's your lower settings that are possibly rich. sluggish is rich mostly.

i don't follow JD's figures but to go up on the idle jet & then turn the pilot screw out to 2 turns sound's too much to me.


[This message has been edited by Taffy (edited 12-18-2000).]


Maybe the #42 at 2 turns would be a safer setting, but he said it idled ok initially and experience says #45/2turns is not over rich.

Some day I'll scan in needle profiles shown in graphs and then everyone will start thinking about throttle position instead of simple jet numbers.

DXM and DRS are night and day apart, 3 clip positions and 5 steps on the needle diameter.


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