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JD jetting

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Put the JD kit in my 04 450 exc without the doing anything else and it made the bike crap. Adjusted the fuel mix screw each way, no help. Raised and lowered the needle, crapola. Finally did some research on the board and found that most everyone did either the BK mod or the updated Honda Diaphram. Decided to try the BK mod. Took the bike to St. Joe Park and :cry: WOW :cry: what a difference. Much better than stock. Took care of the major Bog that I was experiencing with the JD kit. I might fiddle with the timing and squirt time some to see if it can get any better but if it doesn't I don't care because it is magic now. I still have a very slight bog if in too high a gear and I really whack the throttle open.

Overall, don't do the JD kit on a 450exc unless you plan on doing the BK Mod or Honda Diaphram kit.

Matt

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Your newbie status says it all. :cry:

The JD jetting kit has a proven track record on all FCR carbs used on the four strokes in this forum. :cry:

However if diaphram, BK mod and other issues exist it is not because of the JD jetting kit! :cry:

As you say you still have a slight bog in taller gears but it is magic? :cry:

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The best throttle responce is in going from a lean idle (needed for a hot combustion chamber so it will burn the fuel of the acpump squirt) to a rich needle. The stock needle is way too lean everywhere to meet EPA etc standards. The JD kit richens the needle and helps accomplish this. Reducing squirt time from stock 3 seconds to commonly 1 second has no effect on what happens until the 2nd second after the twist. If your experiancing a bog when you twist you have missed something in the setup. Most common error is to evaluate the responce when the engine is cold. Another common deal is to make a change such as putting in the kit, start the engine and stand there and whack at the throttle to evaluate this new piece. That is not real world riding and to jet the bike to respond instantly when not up to temp would require it to be soo rich just off idle that fuel consumption would be a problem.

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Dave that is exactly what I was thinking. A friend put the kit in his WR450 and didn't have a bog hardly at all. I was just commenting that the bog I had took me by surprise. The BK mod made it near perfect. Yes, I did warm it up as always prior to riding it around and rode it around for approx 5 or so minutes before trying to check the bike out with the new jetting. I had an older husky 510 that you had to do this with and so that is just the routine I continued with the KTM450.

As I said in the previous post several other people with 450 exc's have had to do this mod to get the best performance from the jd kit.

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Hi,

well, I just don`t understand the hype about the JD jetting kit!....I`m with you, that the EXC`s, at least my California 525, are way too lean to meet the emission standards......and stock the bike is running like crap!!!

My fix: I went to the dealer and ordered the next richer jet needle from KEIHIN, put it in and the bike runs fine......no problems at all!!!!

So, educate me and tell me the benefits of a 69$ JD kit over a 26$ KEIHIN jet needle!!!!!!

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Flexibility, versatility & overall better performance (probably mileage too).

DJH can give you the specifics better than just about anyone (or JD, but it's probably not his style).

JMHO

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I too was disapointed with my JD kit... AT FIRST.... I was running the blue needle set-up per instructions, my YZF needle with a 45pj and 175mj ran much better even though way too rich.. My friend had been telling how his ran best with the red needle set-up. Well between the instructions saying blue, everybody I knew saying blue, me being hard headed not to mention being po'd over spending $65 for nuthin, yesterday I finally in desperation tried the red with 42pj and 170mj... Woo-Hoo this baby rips!!! No slow speed bog, come's right from idle with grunt right on up. Very responsive. If you were to tell me to do the BK, I would laugh it's that good. It did seem a wee bit too lean at the very top, so I just went to a 172mj and will try it out when the rain stops..

SoCal

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look frist you rejet the bike ofr your pipe next put on the power now. and you wont have the bog.....i have a 05 450 exc and ithe power now is the way to go. 3 rd gear feels like 2nd and no bog in th and 6th gear. so dont be a jack ass and get the power now............. :)

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