JD carb kit is coming along with the Powercore...


11 replies to this topic
  • Gadsen

Posted January 07, 2005 - 06:32 AM

#1

OK, I ordered a JD jet kit for my 450, along with the Powercore IV SA and the quiet core insert. I'm sure the JD jet kit will have some instructions, but this question is for those those who have done it already to save me "trial and error". What jet sizes, clip position should I start with or does the JD kit come with the specs and only one size jet? Keeping in mind, I live at about 500 feet and ride between 500-3000 with a few rides up to 5000, and will have the free flowing Powercore IV SA with the quiet insert too. Will also put in a extended fuel screw at the same time while the carb is out on the bench. :cry:

  • Indy_WR450

Posted January 07, 2005 - 06:51 AM

#2

I have the same set up. Go with a 170 main, blue #5 , 48 pilot, 72 starter, 40 leak jet to start for cold weather in Washington. :cry:

  • ncmountainman

Posted January 07, 2005 - 10:13 AM

#3

the 04 needle was upgraded from 03 i run mine at the 4th clip(stock) with 170 main 50 pilot i hate to say it (sorry dan) mine runs better than dans with the JD needle being the only difference in the setups. the coupla times i rode his bike it had a very noticeable hesatation /stumble at around 1/4 throttle(maybe it'll go away with the new 490 gorilla kit!!). now this is the same bike same jetting,same exhaust same powernow,twinair etc. the only difference was the JD kit. i believe the 03 had problems with the needle but i also believe that the change they made in 04 cured it. my 04 has run flawlessly with the stock needle(at the same altitudes you run). i would try the exhaust first,changing the pilot to 50(48 with the quiet core) and the main to 170. and if it runs great send the jet kit back. :cry: did you get the powerbomb also?? get the sx version if you do.

  • Khari

Posted January 07, 2005 - 12:11 PM

#4

I just put in the JD kit and Zip Ty screw two days ago. I ride at 1000-2000 feet here in Georgia mostly. I didn't even have to pull my carb out. I disconnected the carb from both manifolds and that gave me enough room to do what I had to. I put in the blue JD needle and 170 main. Big difference!

  • Indy_WR450

Posted January 07, 2005 - 01:14 PM

#5

Hey Bob,

Dont forget mine has almost 12,000. miles on the engine, almost 3000 miles since the last valve adjustment, pinched (choking) and leaking fuel line and a small header leak to contend with when you rode it. Rebuild should make it run great again! I also found that my vacuum lines dont seat well anymore and I am replacing them with new tubing and clamps. I cant wait to run the new 490 kit (the stock spec is actually a 439) :cry:

  • ncmountainman

Posted January 07, 2005 - 01:18 PM

#6

ya,ya,ya i knew that would ruffle your feathers :cry: i just don't believe it s needed on the 04. what are you talking about 439??? :cry:

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  • Indy_WR450

Posted January 07, 2005 - 01:56 PM

#7

I believe yamaha just calls it a 450 but it is actually a 449 displacement. Sorry for the typo. :cry:

  • Gadsen

Posted January 07, 2005 - 06:45 PM

#8

Thanks Indy and NCMM, this is the exact info I was looking for. I like others to hash it all out, then I walk in and get all the glory for spending so much time getting my carb set up so nicely! :cry:

NCMM, I'm still using the stock header. I'm not sure if I will change it. But who knows, after a taste of extra power from these existing mods, I may develop an appetite for much more! I'm considering the YZ camshaft still. But that (if it happens and it may not) will come when my first valve adjsut comes up. Thanks :cry: again you guys!

  • Math

Posted January 07, 2005 - 07:19 PM

#9

i just don't believe it s needed on the 04.


What about a 01. Indy just explained to me by PM how he would set a 426 with a PC4 and a JD jetting kit. I might not have the monney to afford a JD kit it in the next couple of months (I got to stop those bike expenses somehow). What would be the best settings with the stock needle? (300-2500 feet, 20-90 degrees)

Thanks to you guys :cry:

  • Indy_WR450

Posted January 08, 2005 - 04:36 AM

#10

You guys really need to think about the needle you put in with any performance exhaust like FMF. I have learned al lot from JD jetting book and the dozen needles I have for my carb. The biggest problem is the main diameter on all the stock needles is too large. This creates the dreaded 1/4 throttle bog situation with a free flowing pipe in colder weather. Larger pilot will help. Higher idle will help. Post your results with stock needles. It is much easier to jet the stock bike uncorked or with an aftermarket with an insert. :cry:

  • ncmountainman

Posted January 08, 2005 - 07:20 AM

#11

the only issue i've ever had with the stock(04) needle involved was the off idle bog but that was cured by a 40 leak jet. other than that i can tune(without even changing off clip #4) the bike for all my riding conditions(1000-5000" and 30-90 deg. temps, ave. humidity around 70 %) just by changing pilot and main jets. the 03 may need help(don't know about the 05 but it sounds kinda screwy) but the 04 in my opinion was on the money. i'm not sure what needle they used(04) or if its interchangeable between models,but there is nothing wrong with it !!! thing doesn't skip a beat anywhere(never has except before i didn't know how to jet it) i thank indy for helping me get it right in the first place( i hope you didn't take offense to the prior statement,it wasn't meant for that):cry: i just think the 04 needle is fine the way it is (with the proper setup) and that theres no need to spend $$ on sumthin' that don't need fixin'!!!!!:cry:

  • Divetruck

Posted January 23, 2005 - 05:25 PM

#12

the 04 needle was upgraded from 03 i run mine at the 4th clip(stock) with 170 main 50 pilot i hate to say it (sorry dan) mine runs better than dans with the JD needle being the only difference in the setups. the coupla times i rode his bike it had a very noticeable hesatation /stumble at around 1/4 throttle(maybe it'll go away with the new 490 gorilla kit!!). now this is the same bike same jetting,same exhaust same powernow,twinair etc. the only difference was the JD kit. i believe the 03 had problems with the needle but i also believe that the change they made in 04 cured it. my 04 has run flawlessly with the stock needle(at the same altitudes you run). i would try the exhaust first,changing the pilot to 50(48 with the quiet core) and the main to 170. and if it runs great send the jet kit back. :cry: did you get the powerbomb also?? get the sx version if you do.

Hi Mountainman,

I have an Aussie 04 wr450 with the powercore iv s/a muffler and standard header. I have no idea what the jetting is as I bought the bike second hand. The bike has all the standard mods and it runs like a dream. I have acquired an SX powerbomb which I will install soon. From your experience, will I need to change the jetting once I install it.

regards,

Nigel
Sydney, Australia.

p.s. Does mountainman like mountin' women?




 
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