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Need a little help guys. I have a 2012 crf450x. I'm planning on installing my fmf powercore 4 slip-on exhaust, deleting the smog crap and doing the 3x3 airbox modification. I live in Georgia so I'm about 1,000 to 1200 ft above sea level. I'm looking to do my carb jetting so I called FmF and their telling me me I don't need to re-jet. I know I probably need to so can anyone help me out with the correct jetting before I tear this thing apart? Any help will be greatly appreciated. 

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Hi Todd,

I would highly suggest getting a JD Jet kit.  It comes with everything you're going to need to rejet and will save you a lot of time in the long run.  the bike comes pretty corked up stock and you're leaning it out quite a bit when you do the airbox mod and smog block off so you're going to want to go fatter.

I have a Procircuit T4, smog delete and airbox mods and I'm running a 170 Main, JD Red needle 3rd clip from bottom, #45 Pilot, Pink Wire Mod, with a  CRF450R Head (no smog shit)

While you're tearing it down, You should check your valve clearances to make sure your exhaust side isn't going tight.

It's really not as intimidating once you get into it, the hardest part is getting the damn carb back onto the head, easiest way is to unbolt the bottom two subframe bolts, loosen the top two and rotate the whole thing on.  Good luck!

Forgot to mention I'm in Oregon, riding 2-3000 ft. 

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2 hours ago, WhiskeyBadger said:

Hi Todd,

I would highly suggest getting a JD Jet kit.  It comes with everything you're going to need to rejet and will save you a lot of time in the long run.  the bike comes pretty corked up stock and you're leaning it out quite a bit when you do the airbox mod and smog block off so you're going to want to go fatter.

I have a Procircuit T4, smog delete and airbox mods and I'm running a 170 Main, JD Red needle 3rd clip from bottom, #45 Pilot, Pink Wire Mod, with a  CRF450R Head (no smog shit)

While you're tearing it down, You should check your valve clearances to make sure your exhaust side isn't going tight.

It's really not as intimidating once you get into it, the hardest part is getting the damn carb back onto the head, easiest way is to unbolt the bottom two subframe bolts, loosen the top two and rotate the whole thing on.  Good luck!

Forgot to mention I'm in Oregon, riding 2-3000 ft. 

I have a similar set up, Yoshimira system, airbox opened up a bit, No-Toil high flow backfire screen removing air filter, JD kit tuned to their recommendations at about the same altitude, smog block off also. The JD kit was a very good buy, because it is absolutely spot on. Even down to changing the needle below 40 degs, which I don't. Just takes a bit longer to warm up. Had a FMF jet kit, which I'm told is a Dynojet kit and it had a mickey mouse main jet adapter I didn't like. Also wasn't as spot on, which is why I went with the JD kit. Bike is way faster than this fat, old man.

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23 hours ago, NEKOOHC said:

You don't need re jet ??

Can't believe they said that , that's crazy

Thanks for your help everyone!!

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