I have an 06 drz400sm with an FCR carb, full yoshimura exhaust, 3x3 mod, stage 1 hot cams, and the exhaust does not have the quiet core. It starts, idles, and revs just fine on the stand but when I ride around at about 1/4 throttle it sputters and jerks. Anybody have any ideas, or if you think it's something other than jetting like fuel screw. It goes away a little bit with the quiet core but I want to jet it without it.

It's not the fuel screw. What is your current jetting / needle setup?

It's not the fuel screw. What is your current jetting / needle setup?

I couldn't tell you that. Sorry I'm a noob when it comes to jetting. It was done by Sudco for the guy when it was in Hawaii. He said it needs to be leaned out but he never had the time to get to it. I have the jets to do it but not sure what ones. Here's a picture of the ones I have.ImageUploadedByThumper Talk1378058330.894820.jpg

Most people will recommend, 160 MJ, 45 pilot. 


Ive found that to be too rich for my bike.  Since  its at 1/4 throttle I would suspect the needle first, but again we need to know what needle is in there. I would start by raising the needle one clip (lowering the clip).  Either way while the carb is out I would see what is in the carb now.

*edit* Doing that will make it richer, if it gets worse you know to go the other way.

Its best to make one change at a time.

Edited by OhioYJ

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