04 WR450 Carb Tuning


23 replies to this topic
  • KAWBOYBILL

Posted May 02, 2009 - 08:04 AM

#1

Anybody used one of the aftermarket Quickshot accelerator pump covers with any succcess ?

  • William1

Posted May 02, 2009 - 08:59 AM

#2

Not needed. Do the oring mod or the stiffer Merge Racing AP cam spring. Then check/set the AP timing. Then select the corrst size leak jet. However, some do replace the AP cover the an Adjustable Leak jet to save them the hassel of swapping leak jets.

  • SPLATT

Posted May 02, 2009 - 04:48 PM

#3

I think this http://www.mergeraci...ableLeakJet.php with this http://www.mergeraci...rPumpSpring.php would be a better set up.

Steve

  • Krannie McKranface

Posted May 02, 2009 - 04:49 PM

#4

Anybody used one of the aftermarket Quickshot accelerator pump covers with any succcess ?


Yes. But not that brand.

I did all the mods: JD Jet kit, stiffer AP return spring, Stiffer AP pump spring, 35 leak jet. After adding the R&D powerbowl and power pump cover (with adjustable leak jet) I noticed a significant increase in throttle response off idle, and going down hill.

Now it feels like fuel injection....

  • William1

Posted May 02, 2009 - 05:05 PM

#5

I think this http://www.mergeraci...ableLeakJet.php with this http://www.mergeraci...rPumpSpring.php would be a better set up.

Steve


Agreed! :excuseme:

Key too, is to check and set the AP timing squirt. Very important and often over looked.

  • TLRam1

Posted May 03, 2009 - 01:09 AM

#6

Not needed. Do the oring mod or the stiffer Merge Racing AP cam spring. Then check/set the AP timing. Then select the corrst size leak jet. However, some do replace the AP cover the an Adjustable Leak jet to save them the hassel of swapping leak jets.


I bought an 04 also and about to tear into the carb.

Why would I need a stiffer AP spring and what is the O ring mod?

How do you set the squirt timing?

  • TLRam1

Posted May 03, 2009 - 02:12 AM

#7

How does the snorkel come out, does it pull out or are there screws somewhere?
Posted Image

Are these the two areas you cut on the air box?
Posted Image

  • William1

Posted May 03, 2009 - 03:25 AM

#8

I bought an 04 also and about to tear into the carb.

Why would I need a stiffer AP spring and what is the O ring mod?

How do you set the squirt timing?


Either the oring or the spring, the spring is longer lasting. You need/want it to provide a more positive response from the AP.

You look in the carb throat, engine off, and nail the throttle, confoirm the squirt just misses the slide. Read this thread about the O-Ring Mod and AP Tuning

How does the snorkel come out, does it pull out or are there screws somewhere?
Posted Image

Are these the two areas you cut on the air box?
Posted Image


It pulls out, not sure if the plate also comes out.

And yes, those areas you cut out.

I assume you have a jetting kit and have done the grey wire and the throttle stop already.

  • TLRam1

Posted May 03, 2009 - 03:46 AM

#9

No jetting kit, I will be buying leak, pilot and main jets.

Want to save the dollars from the JD kit. Can I use the 04 YZ needle jet, is the needle jet the same but has grooves for adjustment?

Grey wire will be done today.

  • TLRam1

Posted May 03, 2009 - 03:50 AM

#10

Where do I run the breather tube at in the air box? From my understanding the 04 has no AIS

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  • William1

Posted May 03, 2009 - 04:01 AM

#11

No jetting kit, I will be buying leak, pilot and main jets.

Want to save the dollars from the JD kit. Can I use the 04 YZ needle jet, is the needle jet the same but has grooves for adjustment?

Grey wire will be done today.


Still would be better off with the JD kit, trust me.

How about the throttle stop??

Where do I run the breather tube at in the air box? From my understanding the 04 has no AIS



What breather are you referring too? Crankcase?? Correct, you do not have an AIS.

  • TLRam1

Posted May 03, 2009 - 01:02 PM

#12

Yes the breather tube from the crankcase that comes out of the top of the heads. I read were others are rerouting or add a "T" for starts in water.

Thanks for your help William, so you think I really need the JD kit :excuseme: , hmmm, on my WR250F I rejetted w/o the needle and was fine so I was thinking I could do the same here OR add the YZ needle IF it had the slots cut to adjust, you are saying this thinking is incorrect? I am in Dallas at about 500 ft. above.

  • TLRam1

Posted May 03, 2009 - 01:03 PM

#13

Oh yeah, the throttle stop I will be cutting off with my dremel.

  • TLRam1

Posted May 03, 2009 - 10:56 PM

#14

What comes in the JD kit, which jets?

  • William1

Posted May 04, 2009 - 03:17 AM

#15

JD kits typically include two needles, five or so mains, a couple of pilots, a leak jet or two, some AP orings. But all kits are different as they are taylor made for each bike.

  • KAWBOYBILL

Posted May 05, 2009 - 06:00 PM

#16

No leak jets in the Dyno Jet kit we bought.

  • Thumper_Bloke

Posted May 05, 2009 - 07:22 PM

#17

Don't need a JD or DJ. both are too expensive and you only use a couple of parts from the kit.

  • William1

Posted May 06, 2009 - 03:02 AM

#18

No leak jets in the Dyno Jet kit we bought.


...and that is one of the reasons, no one reccomends a DynoJet kit. James Dean is the only one worth buying.

  • KAWBOYBILL

Posted July 08, 2009 - 11:51 AM

#19

Does anybody know what size the stock leak jet is on the 04 WR450 ?

  • TLRam1

Posted July 10, 2009 - 03:35 PM

#20

If I have my old on in the garage I can tell you, I tried the smallest 35 or 40? didn't work, soldiered mine shut, that helped a bunch.

Found it, mine was a 60 and I tried a 40.




 
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