2002 CRF 450 Jetting

[Randall450]

I recently bought a 2002 crf 450. I installed a Big Gun Full exhaust. Should i need to re jet the carb and if so how?
Thanks

 

[helio lucas]

http://biggunexhaust.com/information.php?info_id=3
click in jetting specs and you will find big gun recommendations on jetting for your bike... :cool:

 

[Matt90GT]

Dont waste your time on their site.

You need to modify the carb a bit. First off grind down the rivet on the accelerator pump to 2mm in length. Then run a 90 leak jet, wire the accelerator pump arm, run a 45 pilot and stock main. Be sure to get a longer fuel screw so that you can easily tune it.

For altitude you may need a bigger or smaller main/pilot jet. I live at sea level.

follow this link:

http://www.squadpage.com/pandora/Professor RedBeard450 How-To AP Mod.pdf

That is the original of the document, but later discussion they run the 90 leak jet. I have that setup in my bike (dont use any pump covers or aftermarket needles) and it runs like fuel injection. Never hesitates or bogs. Just runs hard

 

[whenfoxforks-ruled]

My son and I, liked the 75 leak jet. It was one of the few that came with the jd kit. Ready racing sells a different ap adjuster, no more wiring. I still have not heard anyone trying the adjustable leak jet? http://www.readyracing.com/pdf/rapidresponse-productsheet.pdf. http://www.mergeracing.com/products/AdjustableLeakJet.php

 

[Matt90GT]

I have installed a few of the R&D AP bowls with the adjustable LJ. It was VERY nice on the YZ250 (07-09) model year. They are hard to get the right size leak jet. Was able to just tune it in just like the fuel screw. But you do have to modify the carb bowl and AP linkage just like the RedBeard mod. No big deal really.

The Ready Racing is nice if you want to blow $90. Why not just use the safety wire at $.05? Yeah.

 

[whenfoxforks-ruled]

Baling wire or bling? The jd o-rings can be copied, they wear out quick. The cam adjustable throttle would be a nice compliment. Snap so quick you can not hold on, to nice and mild.

 

[Matt90GT]

safety wire.

 

[Randall450]

Not sure what yall are talking about with the wiring.. I thought just jetting would do.. Im confused on which wire and what does it do? sorry im just lost

 

[whenfoxforks-ruled]

Set the ap to squirt just as the slide goes by, then: http://www.dirtrider.net/forums3/showthread.php?t=163578&highlight=adjuster

 

[Rich Rohrich]

Not sure what yall are talking about with the wiring.. I thought just jetting would do.. Im confused on which wire and what does it do? sorry im just lost

Start by following the link posted above to the Big Gun jetting specs. That should give you a ballpark idea where to start. Until you get the basic jetting sorted to your satisfaction worrying about whether to fool around with wiring up the accelerator pump mechanism is probably premature.