450r backfire

[Phills450r]

when im at a decent amount of rpms and i let off the gas it backfires/pops a little bit. all i have is the hrc kit that was installed when i bought it. anyone know anything that can be causing this? 2004 450r

[GPracer2500]

Probably a lean pilot ciruit. An exhaust leak is also a possibility.

[Phills450r]

Originally posted by GPracer2500
Probably a lean pilot ciruit. .

whats that :-/ lol sorry

[d3ktrix]

My 05 has the HRC kit installed by honda and mine also pops on decel some when coming out of the higher RPMs.
Like when I shoot down the road in 5th, then let off.

Everyone I ask says the pilot circuit is a little lean.
Either richen the air/fuel screw some or go up 1 size in the pilot jet.

I haven't messed with mine yet as I hardly ever go fast enough to make that happen, so it hasnt bothered me :P

[Phills450r]

where can i get jets from without buying a jet kit

[d3ktrix]

Local honda dealer, should only be a few bux.
Try the air/fuel screw first.
If the screw has to be more then 2.5 turns out to fix the problem, then u need to get the bigger jet.

[Phills450r]

I will try that but I want to get the screw that is easy to turn before I do because its so hard to get to while the bike is running :-/

[GPracer2500]

Originally posted by Phills450r
whats that :-/ lol sorry

There are a couple of different "circuits" within the carburetor. Each circuit is responsible for providing the fuel metering at certain throttle positions.

0-1/4 --> pilot circuit (fuel screw and pilot jet)
1/4-3/4 --> needle jet circuit
3/4-WOT --> main jet circuit

There is some overlap between the circuits but each circuit dominates the fueling in their respective throttle positions.

See HERE (http://www.exriders.com/vbb/showthread.php?s=&threadid=229923) for help on jetting your pilot circuit.