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Jake400sm

stock drz 400 carb.

6 posts in this topic

the carb on my 2008 drz400sm has been bogging down, the airbox was modified and the spark arrestor pressed out of the stock muffler, the symptoms includ bogging aswell as hesitation on the launch. i looked everywhere (without taking the carb off) for a fuel mixture screw with no succes:banghead:. any help would be much appreciated!

Jake400sm

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So the fuel screw on a stock carb is under a round plate that covers the said fuel screw.it's in the front part of carb in front of float bowl.and as far of the symptoms did this just start?is the bike new to you?as you say it's stock , sounds like the jd jet kit may be your friend ,but if this just started out of the blue then somthing may have plugged in carb or?.I'm sure others will post up what to check.Ed

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So the fuel screw on a stock carb is under a round plate that covers the said fuel screw.it's in the front part of carb in front of float bowl.and as far of the symptoms did this just start?is the bike new to you?as you say it's stock , sounds like the jd jet kit may be your friend ,but if this just started out of the blue then somthing may have plugged in carb or?.I'm sure others will post up what to check.Ed

yes, i have found the plate that goes over the hole. but i cannot seem to get it off and im not looking forward to tearing the carb out, and yes it started just after the modification was done on the exaust.. kinda wishing i didnt mess with it at theis point, but oh well the damage is done, so now i just have to go from here.

thanks for the reply

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You can do a quick and dirty test to see if it's just a jetting issue or something else. Just tape up the hole in the airbox to put it back to about the original size (about 2" x 1", roughly, on the SM). If that makes a difference, play with the tape a bit to see how big a hole you can get before it starts running like shit again.

If changing the intake size back to stock is a noticable difference and can get the bike running reasonably decently, fix the jetting. Or, if you're happy with the way you get it to run with taping up the air intake, just ride it. :bonk:

The JD jet kit has excellent suggestions for what combinations of main jet and needle position to use for various conditions. The version of the JD kit I got was the SM-specific version that comes with Allen head replacement screws for the float bowl (there's a good chance of stripping the Phillips screws that are in it). The only other thing I would suggest is to also get a Keintech extended air/fuel mixture screw.

...ken...

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