Turning on a new 2012

I just picked up my first four stroke 2 weeks ago, new 2012 450x. I've always rode smokers so turning this thing on is some what new to me. I don't want to go full out since I bought this with the intent of being able to slow down and ride with my 13 year old son. My built 99 CR 250 is just to much for him to keep up with and it loads up if I slow down. If I want to rip I still have the 99. But this thing's kinda poochy outta the hole and I know it's got it I just need to turn it on. What I am planing is to remove the air box snorkle possiably drill a few holes in the top, get rid of the smog pump, and rejet. This is where I'm a bit hung up. From reading on TT I'm thinking 55 leak, 48 pilot, 165 main, NCVS needle, and topping it off with a R&D flex screw. I've also looked at the JD kits which raises another question. Do the JD kits come with some sort of Dyno sheet that matches mods / no mods with appropriate jets in the kit, what all comes in these kits?

I just picked up my first four stroke 2 weeks ago, new 2012 450x. I've always rode smokers so turning this thing on is some what new to me. I don't want to go full out since I bought this with the intent of being able to slow down and ride with my 13 year old son. My built 99 CR 250 is just to much for him to keep up with and it loads up if I slow down. If I want to rip I still have the 99. But this thing's kinda poochy outta the hole and I know it's got it I just need to turn it on. What I am planing is to remove the air box snorkle possiably drill a few holes in the top, get rid of the smog pump, and rejet. This is where I'm a bit hung up. From reading on TT I'm thinking 55 leak, 48 pilot, 165 main, NCVS needle, and topping it off with a R&D flex screw. I've also looked at the JD kits which raises another question. Do the JD kits come with some sort of Dyno sheet that matches mods / no mods with appropriate jets in the kit, what all comes in these kits?

Yes

Yes

Yes

The JD kit is a box of jets, instructions on which jets to use depending on the state of un-corking, and proprietary JD needles.

Unfortunately, they do not provide a leak jet option, and the JD needles are hit a miss for some people.

You list of jets will work fine.

Gotta open the exhaust too.

What are my options for the exaust? I don't really want to loose the spark arrestor being as I plan to do some riding in some heavily wooded areas and maybe some state land. Is there a good after market muffler that has a better breathing arrestor?

What are my options for the exaust? I don't really want to loose the spark arrestor being as I plan to do some riding in some heavily wooded areas and maybe some state land. Is there a good after market muffler that has a better breathing arrestor?

Yes, several dozen. Anything from DG to Pro Circuit.

Google "CRF450X exhaust "

What are my options for the exaust? I don't really want to loose the spark arrestor being as I plan to do some riding in some heavily wooded areas and maybe some state land. Is there a good after market muffler that has a better breathing arrestor?

You can get a used 05-08 450R muffler and put a PMB end cap with sparky on it. This is a solid improvement and maybe the most cost effective. You could also go with an FMF, PC. or Yoshimura. there are others but I don't have experience with them. There's probably a mod you can do on the stocker to open it up as well. Do this at the same time you fix the airbox and smog pump then you can get it jetted right and not have to worry about it. Once these simple mods are done your 450X will rip. No engine mods are necessary until rebuild time IME. You're in the right place to get the straight skinny, HTH

Edited by cubera

I'm not finding any mods for the OE exhaust I guess the baffle is welded 09 and up. I'm thinking probably a full system is in my future but at $600-$700 not my imediate future.I'm going to pull the end cap tomorrow and see if I can come up with something to open it up. If I end up leaving the exhaust OE for now I'm thinking I may just go with a 155 main for the time being. That has to be better than the stock 142.

It does come off.

You can mod it and keep the SA intact

do a search

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