Yet another Jetting Post – 2001 DRZ400k wont idle

Hey guys,

I just purchased a 01’ 400k, well modified. Its got a pipe on it as well as a ton of protection mods (case saver, skidplate, bark busters, Rad guards, etc…). Well sorted bike, but the previous owner said he just couldn’t get the jetting right.

I found the time to remove the carb and take out the jets and check them out. I also purchased the JD kit, snorkel removed, pipe installed. Bike will not idle, I have the throttle stop up really high to keep it alive, but it really wants to die at idle. There is also a fair amount of popping on deceleration.

Old settings:

MJ: 170

PJ: 50

Needle: Stock, Third Clip

New Settings:

MJ 165

PJ: 50

Screw 2.5 Turns out

Needle: JD Blue 4th clip

At sea level btw….

I am thinking that the pilot jet is too large and causing it not to idle. Am I right in this thinking? Is there anything I can do with the mixture screw to accommodate for this or should I just go out and buy the appropriately sized pilot jet?

pilot jet is way too big. generally when you see that it is becuase at some point someone tried to compensate for the slide plate being installed upside down (goes square end down),broken slide plate or they were trying to cure an accelarator pump related big issue with a huge pilot jet.

Geez, well i guess the best plan of action is to install the correctly sized pilot jet and verify that none of the other components are installed incorrectly.

Do you reccomend a pilot jet of 48 or 45?

45 pilot jet with 2 turns fuel screw when using the jd needles.

So i was just out monkeying with the DRZ and still no luck I installed both a 45 & 48 pilot jet at different times and everything appeared to be OK at first. The bike would idle just fine with the choke out, as well as the idle would change when i would adjust the idle screw. I am beginning to think that the jetting is just fine, it is as everyone as recommends (160MJ-48PJ). I am beginning to think that there is some sort of air leak or pump problem. Here are the exact symptoms:

Bike starts first kick, no problems there. Choke open, idles high. Close choke, idles ok for about 30 seconds then creeps down and dies. My guess is some sort of air leak or something external to the carb jetting.

My first suspect was the hot-start switch, i have since removed it and plugged the hole. Still same results. So its reinstalled now. My next guess is perhaps the coast enrichener is failing, i suppose i could bypass it and see if there is a change, but at this point i turn it back to you guys to see what you think.

Thanks in advance.

did you confirm the slide plate is square end down?

did you confirm the slide plate is square end down?

i guess thats my next step. I just walked inside from putting her all back together and testing... :excuseme:

Id love it if this was the fix.

Well now i am really confused. I took the carb all apart and was convinced that the slide plate was upsidedown.

I then read this thread: http://www.thumpertalk.com/forum/archive/index.php/t-595658.html

The service manual indicates that the slide plate should be installed such that the hole is at the top of the slide ie this picture:

http://i64.photobucket.com/albums/h173/obrianmcc/DRZFCRcarb009.jpg

However the thread that i mention above states that the slide plate installed like that is incorrect.

Which way should it really be? Previously it was installed square side down (hole at the bottom), i then changed it to meet the manual reads, Square side up, hole at the top.

With the plate in that configuration (hole at top), the bike idles perfect with the choke open, when the choke is closed the idle races up to about 5,000 RPM. I adjusted the idle screw as low as it will go but still will not decrease. Back to the drawing board...

Sounds like your just about there, but your idle and 1/8 to 1/4 throttle open is not set corectly. warm up the bike for about ten min, how ever you can. shut the engine off and put the recremended pilot jet in and set the air mix screw to the serv. man recomended position. start the bike with the choke OFF and back out your idle adjustment until she almost sputters out. you may need a second person to help keep it alive. now slowly bring your idle adjusment in 1/4 turn at a time until the bike is at propper idle rpm(check your manual). With the throttle being held steady so that the rpm’s don’t change, adjust the air screw on the carburetor slowly in and out, at 1/4 turn each adjustment, until you find the highest running rpm spot. The engine should noticeably slow when you go in too far. When you back out the screw the rpm’s will increase up to a point and then will not change when you keep backing out the screw. Find the point where the rpm’s are at the highest point and stop backing the screw out right there. When you are satisfied That you’ve found the correct adjustment, shut the engine off and see how far the air adjustment screw is backed out. You check this by

slowly screwing in the air screw in 1/4 turn increments, counting as you go, to see

how many turns the air screw is out from the carburetor.If your air screw is more than 1/4 turn out from whats recommended , this means you need the next size smaller pilot jet. If your air screw is less than 1/4 turn out from whats recommended, this means you

need the next size larger pilot jet. After you have changed the pilot jet in the

carburetor, you need to repeat the tuning process above and find the optimum

rpm point by adjusting the air screw. after doing this you should be set. and remember BE PATIENT

Well now i am really confused. I took the carb all apart and was convinced that the slide plate was upsidedown.

I then read this thread: http://www.thumpertalk.com/forum/archive/index.php/t-595658.html

The service manual indicates that the slide plate should be installed such that the hole is at the top of the slide ie this picture:

http://i64.photobucket.com/albums/h173/obrianmcc/DRZFCRcarb009.jpg

However the thread that i mention above states that the slide plate installed like that is incorrect.

Which way should it really be? Previously it was installed square side down (hole at the bottom), i then changed it to meet the manual reads, Square side up, hole at the top.

With the plate in that configuration (hole at top), the bike idles perfect with the choke open, when the choke is closed the idle races up to about 5,000 RPM. I adjusted the idle screw as low as it will go but still will not decrease. Back to the drawing board...

goes square end down.

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