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Discussion Starter #1
ok, I have been messing with this thing and had the carb off too many #^%$ times!! I have a 2008 DRZ400SM with a 3X3 mod, full RS2 yosh pipe with the spark arrestor removed, and a Dynojet kit. Also the smog stuff is removed. I went with the recommended jetting with a 155 main and it think the needle in 2nd clip and running a stock pilot with the air screw 3.5 turns out. bike starts up fine, idles fine, no real flat spots either, but the bike is flat out slow. I tried a 160, 155, 150, 147, and the stock 142.5 main. when I had a 155 in there, I took the side cover off the air box and for the 1st time it felt like a 400 and not a 100cc bike. That tells me it's rich? so I went leaner, still feels slow. What the hell???? Anyways, I have been wrenching on bikes for 18yrs and every single bike I have ever owned I had spot on jetting. My only other bike that was hard to jet was my 1999 CR250R after I added a 330 bigbore kit. Anyways what jetting are you guys running (people who have a 36mm stock carb and full exhaust) I looked at TT and saw anything from a 160 to a 142.5 main? So anyone????? Thanks
 

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slideways just went threw this,I think,158main,1 step up on starter jet,3rd clip down,2 1/2 turns out on enrichment screw,and did you plug the vacuum source at carb from smog junk?or maybe check vacuum diafram on top of carb????:headscrat 39mm FCR the bomb......
 

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Discussion Starter #8
update

Saturday I devoted to day to looking into it. I picked up a #25 main and after messing with it i found the intake boot on the right side had a slit in it and was causing an air leak. I ended up with a 25 pilot, a 160 main and the needle on the 2clip and air screw 2.75 turns out. bike finally runs great. I guess this must have happened on the 1st time of the jet swap, 4 months ago.

Anyways I am happy now, thanks :thumbup::clap:
 

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thats good you found the problem with the slit boot but if you live in so cal you might want to drop that needle down to 3rd clip, If you have it on the 2nd clip you might here it popping when you let off the throddle,dropping it down to 3rd clip will take care of that.
 
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