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Help with 04 CRF450

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My CRF will not run right. When I drill the gas it will hesitate. It started to do this one time before but only lasted for about 10 Min. Know it does it all the time. It's like riding a two stroke I drill the gas get hesitation and then BAM all power. I have adjusted the air screw and that makes no difference at all. I just want it to run like it did when I bought it. I did check the valvues and they are ok and I put a new gasket on the head pipe.

Not sure what to do know?

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Did you check the fuel screw? What about looking at the plug? Wet Dark=Wet, Light=Lean, Tan=Perfect

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I checked the fuel screw and played with a ton of different settings and nothing made it better. I also changed the plug it was a little dark but did not look to bad but I replaced it anyway and it is still doing the same thing.

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Trex. I have worked with the same carb a lot on KTM and most recenlty the 05 Husky but I have no idea what componants (needle in particular) are in the Honda. What fixes them on the other bikes is the JD kit. The stock setup for the others is too lean on the needle and they offset that with too rich on the pilot, the JD kit corrects this and makes them much more responsive! Worth every penny

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Looks like that is my next step.

Can anyone that has the jet kit for the 450 and lives in the midwest tell me what their settings are and what works best for them. My CRF is stock.

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If it ran fine in the past why do you think putting in the JD needles will suddenly fix it?

It sounds like it is hesitating off-idle. Is that correct?

The first thing I would do is pull the subframe off and make sure that the accelerator pump is functioning. When you twist and hold the throttle, a stream of gas should spray from the little brass nozzle. If you have no stream of gas then you are getting lean hesitation off-idle. You will then have to pull the carb and clean the AP pump, possibly have to replace the diaphragm, etc.

Check that and report back here.

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That is what I was thinking why all of a sudden now!

I will check the pump and carb when I get a chance. Might be a couple of weeks but I will let you know what I find out. Thankx

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I took the carb apart and checked the AP pump looks good, diaphram looks good checked all jets looks good. I have not put it back together yet to try will try in a couple of days. 😢

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The first thing I would do is pull the subframe off and make sure that the accelerator pump is functioning. When you twist and hold the throttle, a stream of gas should spray from the little brass nozzle. If you have no stream of gas then you are getting lean hesitation off-idle. You will then have to pull the carb and clean the AP pump, possibly have to replace the diaphragm, etc.

I would do the same as skthom2320.

Did you see the stream of fuel from the accelerator pump nozzle with the subframe and airboot off?

The squirt needs to be visible. The stream should last about 1/2 to 1 second.

What pilot jet, fuel screw setting, needle code, and clip position are in the carb now?

You may want to check the float level to be sure it's not set too high since you have everything apart. (A painful process getting at the carb on CRF's, I know too well)

James

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I took the carb apart and checked the AP pump looks good, diaphram looks good checked all jets looks good. I have not put it back together yet to try will try in a couple of days. 😢

You haven't told us if it actually creates a stream of gas when the throttle is actuated and the carb is on the bike.

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I have the carb back on the bike but have not had a chance to try to see if it shoots a stream of gas yet.

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Okay it shoots a stream of gas. Now I just need to but it all back together and see what happens.

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Trex,

I know it's been a while since your original post but hopefully your still watching. I've had the same issue with my 04. I've been running 1/2 112 octane and 1/2 92 octane mix, I don't know if that has anything to do with it but I just ordered the JD Jet kit, i hope that works.

I've tried everything!!! I've torn my carb apart several times with the same results. My buddy has an 05, put the jet kit in and that fixed the problem. The strange thing is that this problem gradually got worse, I wonder if I need a valve adjust? I hate throwing parts at anything but i've heard great things about the kit. I'll let you know how everything works out by this weekend. (My neightbors are gonna be pissed!!! Oh well )

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If your responsiveness is gradually getting worse, check the valve clearance and clean the accelerator pump diaphram. Dirt/dust can build up on top of the diaphram and reduce it's effectiveness.

James

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bctripz, I run high octane in my bike too. I'm curious to see how it works for you with the JD Kit. I'm going to try to finish putting my bike together this weekend so I can see if cleaning my carb worked at all. James said something about valve clearance! I checked mine and they are ok. If my bike does not run right I do not know what to do. I want to know why all of a sudden it began to run like crap.

Just to recap all I have checked:

Adjuste air screw - Nothing worked

Checked Valves - OK

New Plug - Old plug was a little black but replaced anyway

Checked for Air Boot leak - None

Checked and replaced gasket on head pipe

Took carb apart cleaned/checked diaphram (Looked ok)

😢

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Have you tried richer and leaner needle clip positions? They may be worth testing too.

James

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James,

I live in San Diego and ride 95% of the time in the local dunes (Glamis). My friend has an 05 with your kit and is using the blue needle but doesn't remember the clip position. He tried your recomendation that came with the kit and the bike was falling on it's face. If you don't recall i guess we can tear apart his bike but would rather not.

Do you recall what you recomended to him/us in T.T. for that problem?

Thanks in advance

Eric

P.S. Trex- No disrespect for using your thread, I hope you don't mind.

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Eric,

The blue marked needle in 3rd from top clip or red marked needle in 5th from top are usually the preferred settings. Use the fuel screw to adjust the idle and response from idle. Keep the stock #42PJ, which you may want to replace if there is any chance of it being clogged. Use a #172-175MJ with the kit needles.

James

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