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new 400 exc jet kit?

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I just bought a 2006 400 exc today and when I got it home it seems to be lean on the bottom with some hesitance when bliping the throttle( to the point that it stalled a couple of times bliping the thottle. I do not see a jd kit for the 06 400. Does the 06 400 use the same carb as the 03-05 400? could I use the 03-05 jd kit?

Jason Robb

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JD lists a JDK002. This is what I just put in.

Also went with a 45 pilot. I haven't tried it out yet though.

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My 06 450 was doing the hesitation thing even after re-jetting, I turned up the idle speed a bit which seemed to help. It felt like the idle speed was slow enough that the ACR was still engaged.

TONY

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I see JD lists the JDK002 part number up to "05" for the 400 EXC, but not for the "06" model? I can't find they're website for any further information or a phone number. Can you buy direct from them or do you have to go through another supplier.

I'm having the same problem after just purchasing a new 400 EXC, popping on deceleration and even a little during acceleration and a little bogging. Also, the bike requires a long time warming up on choke before being able to run off choke. I'm hoping a jet kit while solve these problems. Any advice is very much appreciated.

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Contact JD thru jdjetting.com. I think he will say it uses the same kit as 03-05, the other thing you need is the Honda diapram which he also sells. Decl pooping only tells us the exhaust pipe is hot, you can cool it down with richer jetting but it will probubly still pop after rejetting as I beleive what your experiancing is caused by an air leak at the exhausts head pipe to cylinder head junction. This should be sealed by removing the pipe, coating the inside with hi temp silicone, reinstall, then do not start the engine for a few days while it sets up.

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Dave,

Thank you very much for your help, I remember reading some tread about sealing the exhaust with silicone but it had no details. I'll have to perform this modification eventually, but first I have to look into an overheating problem, I'm starting to worry about mt recent purchase of this bike...

Thanks again for your help Dave

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Rompin,

Don't give up on your new toy, they are great. They come from the factory lean, which makes them run a little hot and might contribute to the pop on decel. The bog will be cleared up with the JD needle and the "honda" (shorter squirt duration) accelerator pump diaphragm. A little fine-tuning and it'll probably exceed your expectations :applause: . I geared mine down quite a bit (13-52) to give me more bottom end jump with very little sacrifice in top end (they're geared very high) :D .

Dave has these carbs figured out very well, so I'd take his advice :prof: .

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Nordegg,

Thanks for your vote of confidence. Have you had any overheating problems with your 400 EXC (although I see you do live in Canada, thus cooler conditions)? After reading the cooling section of the owner's manual and some posts here, it seems there may be a cooling fan kit available for this bike, with how easily the bike overheats it should have been standard equipment on this bike... I'm going to look into this kit, hopefully it will solve this problem.

Thanks again!

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Nordegg,

Thanks for your vote of confidence. Have you had any overheating problems with your 400 EXC (although I see you do live in Canada, thus cooler conditions)? After reading the cooling section of the owner's manual and some posts here, it seems there may be a cooling fan kit available for this bike, with how easily the bike overheats it should have been standard equipment on this bike... I'm going to look into this kit, hopefully it will solve this problem.

Thanks again!

I can't see you needing a cooling fan once you get the bike properly jetted. My 450 EXC has yet to overheat and I've ridden it in all conditions. However, I don't let it idle for long when I'm stopped, I try to keep moving by either leading when with slow riders or letting them ride on so I can catch them. Just get your bike running right, JD makes jetting it pretty easy.

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Rompin,

I don't have overheating problems, and by comparison my buddies' CRF450's DO. I also run a flatland radiator guard, which probably cuts the airflow across my rads. Where I'm at is around the same temp as NJ (in the Summer) just less humid, there are lots of guys in very hot places with no fan and no overheating, so one isn't neccessary.

First thing, get the jetting right, this will make a big difference. Second, make sure the level in the rad is correct. Many (most) new riders have the level too high and when the fluid expands with heat it squirts onto the exhaust pipe. That isn't overheating, it is just setting it own proper level. The fluid should be just covering the fins, well below the fill cap. Thirdly, you can't sit and idle ANY of these high performance dirt bikes; when you stop, shut it off. If none of this changes anything, make sure you don't have an airlock in the top of the head; there is a bleed point if you check the manual. I'd be surprised if you really need a fan, but if you end up moving really slowly due to highly technical terrain... maybe.

Good luck! :applause:

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Nordegg,

Thanks again for your help. I just ordered the JD jet kit, but am still considering the cooling fan kit also because the ease at which the bike overheated a few times. Although I did let the bike idle on a few occasions for short periods of time and didn't think it was a bad thing at the time as my riding buddies were idling as much or more than I was. I lost about 1/4 qt. of coolant so it wasn't just bleeding off excess coolant.

Most of the riding I do is slower speeds so I think I will need as much cooling as possible. I didn't know these bikes were prone to overheating, I didn't even realize it is an open cooling system until investigating this issue.

I'll see how the jet kit performs, I hope it helps keep the engine running cooler and running better. Thanks again for your help...

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FWIW, check your pilot jet, if its a 42 change it to a 45 as the 42 is just to lean. Also add a fuel screw with the big external knob, be sure to get a brass one not alum or steel. Makes low speed adjustments way easier. Also recommended idle speed on these is 1800 rpm which is quite a bit higher than most of us are used to.

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I am looking at the directions for my JD kit for my 525 EXC right now. It has a whole page of instructions specifically for the 06 400 exc...

It is the JDK002 BTW.

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I just installed the JD jet kit over the weekend and so far love it. The process was easier than I thought it would be.

I used the blue needle 3rd clip down and the small o-ring, 1 1/4 turns out on the fuel mixture screw. It runs a little better with less off idle bogging and a little less popping during decelleration. I also noticed I can take it off choke much quicker after a cold start up as opposed to the stock jetting.

I may try the red needle sometime as I've read some 400 exc owners say they though it ran better than with the blue needle. Overall, I feel much better knowing I have a richer mixture and better performance.

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I ride with my sons and my 400 gets too hot when I stop to wait for them or go too slow. The KTM radiator kit bolts right on to the rad. and is a nice kit for $90 or so. Ijust put it on but a friend swears by it.

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I would run the radiator fan. I richened up my jetting quite a bit and I have still had the fan come on in a sand wash tapped in 4th. These motors run hot and any help you can give it is good. One of my riding buddies did some desert riding on a 525 and the fan never shut off all day.

John

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