jetting question?

8 replies to this topic
  • miguelitro

Posted April 07, 2005 - 10:00 AM


Got the new pig figured out
went with a 178, rather run rich than lean,
checked fmf site (fast mother f^&ker) good sit to recomend to new guys like me! good approximate jet sets..
just had to raise the needle too like they said
now allis good

Sorry guys, i'm sure biggity picked all your brains about the same bike,2002 xr650r, and he never had any luck getting the jetting right.

hard to start
lean pop at idle and deccel
seems to run right on the pipe

182 main jet(up above the carb drain) seems small to me for a power bomb header, and opened up bike. i have a larger jet 188, which seems too large.

Here is the Questions-
If I raise the needle a cliip this will make the idle circut richer but the other circuts too?

Adjusting air fuel mix screw will do the same, richen all circuts?

larger main jet will help?

What size jetsmain/pilot, just so i can have some idea, are you guys running?


  • miguelitro

Posted April 07, 2005 - 10:21 AM


okay, went to the pig pen and learned that I know nothin about jettin 4-strokes, have it down on smokers but this is tough stuff. gonna pull the carb, check the needle position, and pilot jet# after work.

Thanks for help and patience.

  • SaltyWalrus

Posted April 07, 2005 - 10:22 AM


If you are holding the needle with the tapered end down, the way it sits in the carb, raising the clip will lower the needle, leaning the jetting out at closed or low throttle settings. I am running the replacement needle in the middle clip position. 182 sounds rich to me, never mind 188. I am running 172, uncorked with an HRC tip and a uni filter. I may switch to a 175 for cold weather, but 172-175 seems pretty close. I get a tiny bit of decel popping, but plug is a light tan, so I am pretty close.

Now someone correct me if I am wrong, but opening the fuel screw will richen the low end jetting, and closing will lean it out. Start at 2 turns out and either adjust for a smooth idle, or test ride bike at 1/2 turn adjustments. I went for a full ride at 2 turns out, then another ride at 1.5 turns out, so on... just to compare behavior. I think I settled pretty close to 2 turns out.

Good luck!

  • miguelitro

Posted April 07, 2005 - 11:05 AM


SW- thanks for that info.
I have been reading enough to know that 182 is a LFJ)large friggen jet!) and I dont think that is the problem. I'm going to check things out first but I bet I need to lower the clip and reset the airfuel mix screw.
its time to get everything set to stock, then adjust for mods,then dial in. more work for me, which of course is really exciting when its a new bike!!!
Thanks and i'll tell you guys what i find.

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  • hill5150

Posted April 07, 2005 - 11:07 AM


I run the needle in the middle w/ xr's only big gun pipe/exhaust uncorked 68s, and 175 runs awesome never pops and kicks over 2nd start every time. :naughty:

mess w/ your air/fuel mix after it idles for five minutes to get it right. :naughty:

  • Max Power

Posted April 07, 2005 - 11:10 AM


182 main..... Wow. Seems a bit rich to me.

My Bike is uncorked with Air box opened up and full Akrapovik exhaust.

I'm jetted for 4000' to 8000' and run a 165 main jet, the needle and pilot that came with the power up kit. Needle set full lean. Clip in the No. 1 position (at the top).

Idle screw at factory setting.

Bike practically starts by itself.

Maybe try a 172 main and move the clip up 1 or 2 positions.

Also, after taking the seat and gas tank off to change needle settings, I just loosen the clamps in front and behind the carb and turn the carb about 30 degrees. Way easier then pulling it right out.

  • jcoyne97222

Posted April 07, 2005 - 11:45 AM


I followed the pig pins instructions and mine runs great. I ride from 500' to 1500' 175 Main, 68S pilot, carved out restrictor in the intake and removed the airbox plug and snorkel. I also had to remove the smog pump because my bike was a California bike. I drilled the stock tip out to 1 3/8" and installed some spacers between the baffle and the can. Starts 2nd kick and then I turn the choke to the middle position for a minute and then let'er rip. JC

  • frankstr

Posted April 07, 2005 - 01:20 PM


Or move up to the Edelbrock carb.. :naughty: Thats what I'm doing... :naughty:

  • miguelitro

Posted April 07, 2005 - 01:30 PM


Edelbrock, man dont even say that word. even though i got a stealing deal on the bike I'm fairly broke after the purchase! just enough to reg it and ride it as much as possible before racing next weekend!
You know how much they teachers in Cali, its a friggen joke!!! But it beats a real 12 month a year deal so I aint complaining, heck once your used to being poor and hungry its nothing.

I think, and no disrespect to Biggity because he told me so, that the jetting is off all around and need to go back to a reasonable starting point then be tuned so thats what i;m gonna do.
Thanks alot to hill and jc for sharing their jet specs. i'll get it spot on soon 'nough!

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