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05 rmz450 1/2 throttle studder after rebuild

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I have an 05 rmz450 that the cases were cracked. The bike ran great other than this. I replaced the cases and did a complete rebuild. The throttle cables were fraying so I also replaced them. That was the only thing I did with the carb. 3 weeks later I now everythign finished but Now what im getting is a 1/2 throttle studder/cutting out feeling, but it is only there when i hold steady around a sweeping corner or cruising down a straight at steady throttle. I have it jetted richer because its below 30 degrees on the ice. At that point I had a 45 pilot jet, 170 main, fuel screw at 1 1/2 turns out. So from there I lowered the needle (raised the clip) and it ran much better but the problem still is present. I want to lower the needle one more notch but i took a look at the plug and it is definitely more white than it should be.

I am very confused with this and I am not sure what esle to do. The bike runs like it is rich at half throttle but the plug is showing very lean. I am hesitant to lower the needle one more because of this. What could I possibly be missing? The bike starts in one kick and run amazing everywhere else besides cruising steady 1/2 throttle. I have double checked cam timing, cleaned the carb and made sure all electrical connections are good.

Edited by ben782

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After playing around with the jetting, figuring I have nothing to lose, I now have the correct plug color: light chocolate color. But the bike still runs like it did before. I now have 165 main jet, 45 pilot jet, 1 1/4 turn fuel screw and needle is one clip richer than stock. Today it is about 40 degrees.

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I've got an 05 and 06, and they both run best when jetted very close to 07 stock (42 PJ 170 MJ NCYR needle clip #3, fuel screw 2 turns out). In colder weather a 45 pilot helps with cold starting. If you're running the needle on clip #5, that sounds rich enough to cause your 1/2 throttle stutter - try #4 then #3 and see which produces the best midrange power and responsiveness.

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Thanks I will definitely give that a shot. Would you worry about plug color if I got it to run good in that rpm range. When I was getting closer the plug seemed to be getting pretty white?

Eddie - are you refering to just replacing it with a new oem needle jet? I dont think they come in different ranges thats why im asking. I obviously know the jet needles come in different ranges.

Thanks again!

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