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CRF450X Death Stumble

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Recently picked up a 450x to replace my stolen R. I decided my old ass finally deserved a button. It is bone stock and the carberation seems spot on except for the occasional low speed burble. Last weekend I was happily charging a log across the trail and when I went to pick up the front end it just sorta coughed and died. I of course did my best superman impression. This has happened more than once and I have to say sorta sucks.

So reading the stickies it looks like the AP mod is probably my starting point. If I wanted to keep the stock muffler what jetting and mods would I start with to get this bike running as well as it can?

Other questions are Smog shit?? Do I have it??

What the hell is the pink wire mod??

Cut the airbox or just yard out the snorkle??? Can I get by with the stock needle or do i need to go to JDs kit???

I know this info is here I am just having a hard time piecing it all together and separating actual knowledge from the BS.

Thanks,

Berk

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I have a JD jet kit, top and sides of the airbox cut (although if I had it to do over, I would just cut the top), and an aftermarket silencer. Those mods completely took care of the low speed flameouts. In Illinois, the bikes don't come with the smog stuff; not sure about Oregon.

This past weekend, I was riding in a sensitive area so I reinstalled my stock silencer (with the baffle modified). I noticed that it would flame out with the stock silencer where it doesn't with the aftermarket silencer (although I didn't rejet or mess with the fuel screw for that one trip).

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The smog pump (if you have one) is a big shinny pump on the right side of the head with a bunch of hoses coming off it. You can buy a block off kit for $35.

The JD kits give you everything you need. It will even suggest how to cut the air box. You might want to make sure the jetting is correct before you look into the AP. The AP changed in '07 or '08. I have an '08 and it runs spot on with the JD main jet, needle, top of the box cut and the smog pump removed. Good luck.

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yep i don,t think i have the smog shit I am in Oregon and it is an oregon bike. I forgot to mention mine is a 2006 crf450x.

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I don't think the out of CA 05 and 06 models had the smog stuff...it became the standard nationwide in 2007. If you don't have anything hanging of the right-hand side of your cylinder head then you dont have the smog stuff installed. Fix the jetting first before you do the AP mod...if you even need to. Also, a 55 leak jet woudln't hurt either.

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you can uncork the pipe by undoing the 4 bolts on the back of the pipe and undo the bolt on the bottom of the tip of the pipe and then use wd40 and elbow grease to get the little plug out. It helped my dads bike but it still doesnt have the response of my 250.

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I have the 06 450x. I did the JD kit, and followed the instructions. Worked like a charm and the bike has run very well since. It took less than an hour, and that alone was worth paying for the JD kit. I ride from about 3000 ft to 10000, and I ought to drop the clip one notch when above 6000 ft. Never done it. I've also run in the low lands at 1700 ft, man that thing is much faster down there. I also put the FMF Q4 on, but that was about a year after I did the JD kit. The only complaint I have is the bike is a bitch to start when it's cold, like below 40 degrees out.

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IS there a thread about this and does it really help?? I have always had mixed results modifying stock silencers

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IS there a thread about this and does it really help?? I have always had mixed results modifying stock silencers

There are quite a few threads on this. I decided to leave my silencer stock and I was surprised how strong it runs. I don't think the gains are worth it in my opinion.

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Mines an 05 I bought the jd kit run the 170 main cut the sides of the air box cant remember which needle I used. Left my stock muffler alone I hate a loud bike and have no flame out since this before hand If I tried to loft the wheel in a hurry unexpectedly it would bog right out and die very scary!!! As far as the above on the hard start when cold do you pump it 6-8 times when cold before starting??? Does the trick for me and it gets pretty cold here in Mi.

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Mines an 05 I bought the jd kit run the 170 main cut the sides of the air box cant remember which needle I used. Left my stock muffler alone I hate a loud bike and have no flame out since this before hand If I tried to loft the wheel in a hurry unexpectedly it would bog right out and die very scary!!! As far as the above on the hard start when cold do you pump it 6-8 times when cold before starting??? Does the trick for me and it gets pretty cold here in Mi.

Nope, I'm scared to pump it. I've tried once or twice, but never 6 to 8. I'll try it.

As for crossing the logs. I try to use the clutch to loft the front wheel, but sometimes there just doesn't seem to be enough time. Maybe I should leave a finger or two on the clutch at all times.:banana:

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I usually have a finger or two on the clutch and in fact last weekend had it flame out while using the clutch to pick up the front.

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Hey, I live in Redmond, Oregon. So my jetting should be close. I changed the jetting on my 06 to a 165 main, 3rd clip position, and did the O-ring mod. No need for JD kit. Cost only a few dollars for the main jet. Now it's so much motor, I can't believe it was hiding for as long as it was. Try these things and adjust your fuel screw if needed. I didn't need to. Maybe try a 45 pilot. People around here have mentioned a 50 leak jet. But I didn't use it. Take the snorkle out. These changes totally enhanced the bike. The O-ring mod must work because I tested it on tight trails trying to see how responsive it is. It snapped like never before. Other than that, a Boysen Quickshot is on there. No other motor mods. Stock pipe. I say give it a whirl. Save money. If you don't like it, buy a JD kit.

Good luck!

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Nope, I'm scared to pump it. I've tried once or twice, but never 6 to 8. I'll try it.

As for crossing the logs. I try to use the clutch to loft the front wheel, but sometimes there just doesn't seem to be enough time. Maybe I should leave a finger or two on the clutch at all times.:banana:

The manual says give it three turns before starting in cold weather.

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3 never works for me below 50. Its more like 8-10 before it lights. Once it is warm it starts very easy. I start with 5 turns.........hit the button, if nothing 3-4 more........usually sputters to life. Not sure if this is common or if my settings/jetting is off. I was going to inspect the pilot jet to see if it was completely clear but bike runs and idles fine after it starts and warms a bit. I read that enrichining the air screw a 1/4 to 1/2 turn helps with cold starting.

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The only complaint I have is the bike is a bitch to start when it's cold, like below 40 degrees out.

I totally agree with this. :banana: I run the stock pipe for now, but a Q4 is in the future.

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I go with the same starting procedure used to use with the old R. Choke and fuel off and three kicks. Then turn fuel and choke on give it three or four turns of the throttle and blammo!

Now back to my ????

Pink wire anyone? W T F is that? And do I need to do any thing with it??

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Switching out the pink wire (under the left number plate) raises the rpm when the rev limiter kicks in. I did the mod but didn't notice any difference since I rarely get close to the rev limiter.

Edited by Crash_Bandicoot

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Hmmmmm this must be why my bike does not feel like it will bomb fire roads as fast as my R. I may have to play with that. Anyone have a how to linky??

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I don't know for sure, but I assumed the X used a 500 rpm lower rev limit because the smaller valves and different cam don't make much power in the missing 500 rpms.

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