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Jetting for 505 SXF -- Loud Popping

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I installed the JD jetting kit in my '07 505 SXF about a month ago with:

  • High elevation needle.
  • 180 main.
  • Stock pilot.
  • All the AP mods.
  • Mixture screw 3 turns out.
  • Iridium spark plug.

Typically ride about 3000-6000' anywhere from 30 degF to 100 degF.

After installing the JD jetting kit (with the jets/needle recommended in his kit for my elevation), I was getting massive amounts loud popping when decelerating. I've read where this can either be caused by the bike running lean or fat. The main that I pulled out of the carb when jetting was a 160 main (bought the bike from a guy in CO). With this main I didn't have any popping at all, although it almost had to be running lean at my elevation, IMO.

I've since swapped in a smaller 178 main with the result of a little less popping. What do you guys think? Am I going the right way? The pipe has never been off the bike, so I don't think air is getting in. The bike doesn't run hot or boil over ever. I pulled the spark plug and it doesn't look abnormally white or black for that matter.

Any ideas?

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I installed the JD jetting kit in my '07 505 SXF about a month ago with:

  • High elevation needle.
  • 180 main.
  • Stock pilot.
  • All the AP mods.
  • Mixture screw 3 turns out.
  • Iridium spark plug.

Typically ride about 3000-6000' anywhere from 30 degF to 100 degF.

After installing the JD jetting kit (with the jets/needle recommended in his kit for my elevation), I was getting massive amounts loud popping when decelerating. I've read where this can either be caused by the bike running lean or fat. The main that I pulled out of the carb when jetting was a 160 main (bought the bike from a guy in CO). With this main I didn't have any popping at all, although it almost had to be running lean at my elevation, IMO.

I've since swapped in a smaller 178 main with the result of a little less popping. What do you guys think? Am I going the right way? The pipe has never been off the bike, so I don't think air is getting in. The bike doesn't run hot or boil over ever. I pulled the spark plug and it doesn't look abnormally white or black for that matter.

Any ideas?

9 times out of 10 the dec. popping is caused either by a lean condition, an air leak in exhaust or both.

I´ve never,ever come across dec. popping caused by a rich condition so i wonder ...

By the way - it´s not recommended going that far out in mix screw. You run in a risk of it getting outscrew itself. And since you need to go that far out with it it would almost indicate that you need a bigger pilot jet.

In most cases (that i´ve come across) the dec. popping is caused either by too lean pilot jet (or the mix screw being closed too much) or too lean needle /clip position. I would start by changing to next size in PJ (and the screw 2,5 turns out) and if that doesn´t help try the blue needle in the same clip position. If it gets too rich (with the blue needle) then try the red needle in one clip richer.

Also - how does the popping occur ? Slow speed going downhill throttle closed, medium speed when you chop the throttle, flat out/chop or in every situation ??

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you ca also check the exhaust connection ... (mid to muffler) some people apply liquid gasket (Hi temp silicone) to help seal this connection, ... apparenlty this is one of the causes of decel pop, my 505 pops on decel very often, I don't worry about it as I know my jetting is okay, ... I have a tube of permatex on the bench, next time I have the muffler off I'll lay some on there, ...

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The decel popping occurs when chopping the throttle at about mid-RPM and up. If I just barely keep the throttle open during decel, the popping goes away. I'll swap in the next size up pilot this weekend along with playing with needles/clip and try that out.

I'm fairly certain that the pipe doesn't have an air leak, as it never popped at all...until I installed the JD jet kit. But who knows.

Thanks for the advice.

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505 comes stock with a 42 pilot... 450 comes with a 40....

You are past 2-2 1/2 turns out on your fuel screw meaning you need to go richer on the pilot....The fact that when you very slightly open the throttle on decel (bringing the main jet into play) and the popping goes away also confirms a lean pilot......try a 45...:bonk:

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I run around the same altitude, if not a little higher on average. I am usually in the 5000-7000 range most of the time. I do have a Yoshimura silencer, and I always run the TEC (quiet) insert, so the jetting is just as happy with this setup as it is with the stock silencer.

Stock needle, two clips from top

182 main

45 pilot

2 to 1-1/2 turns on the fuel screw

R&D ALJ at 2-1/4 turns out

No issues that can't be solved for the majority of riding by just moving the fuel screw lightly.

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Forgot to post back with results after fiddling with the carb.

For future reference if anyone digs this topic up, here is what works best for my bike:

Stock '07 505 SXF

Main: 180

Pilot: 45

Needle: Red, clip in 3rd from top position

Mixture Screw: 1.25 turns out

Tested Environment: 3000-7500' 30-70 degF

No more loud popping on decel! However, occasional popping has occurred with changing temperatures/elevation, but slight adjustment of the R&D mixture screw quickly solves this. Also feels like it pulls a little harder off-idle.

Thanks for everybody's help!

:smirk:

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