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Yfz 450 Atv

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Just rejetted a stock 05 yfz450 atv with no lid and a twinair filter no spark arrestor in the pipe and the carb spring mod (moved coil attachment point) done nothing else.

used JDJETTING KIT Red needle 168 main and a 45 pilot with 2 turns out on the fuel screw

Now i have a mid to high speed miss in second and up near the top of the power

thought it was the throttle cable being to tight and the TORs kicking in but adjusting that didnt help much at all

I ride at about 1200 feet and 65-90 deg temps

Anythoughts on what the cause might be ?

the bike ran great before i started am i rich or lean or what ?

thanks

R

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Got rid of most of my mid range stumble but still have a high speed skip

i turned fuel screw to 2.5 to help decel popping and droped the red needle to the 4th clip as well as rermoved to much oil from my twin air filter

my question is it lean just on top now and would the blue needle help or the 170 main ?

thanks

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RPMR6,

With "no lid and a twinair filter" on a YFZ450, I would think the top-end would be lean with a #168 main jet. Try bigger main jets in increments of 2 steps and compare.

James

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Might want to try a 165 main jet.....I tried the 168 several times and kept getting a stumble at high rpms in all gears but especially in 4th and 5th. The 165 main worked best for me.

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I ended up doing just that after i clean some oil out of my twin air filter (noob had it too oiled) and dropped the needle one clip it got better with just a stutter up the wfo. that made me think rich so i swapped to the 165 main and it pulls like a freight train now :)

Thanks for the help :)

R

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