white plug???? 744 feet 160mj 48pj Help!!

4 replies to this topic
  • 450yjoffroad94

Posted March 24, 2003 - 12:20 AM


160mj 48pj and stock needle at 744 feet richened piliot screw still popping on decel and white plug any help??????????? Should i need more fuel at 744 fee :shocked:t?????

  • ThumperWR450F

Posted March 24, 2003 - 01:01 AM


i may be wrong on this but i assume the higher the elevation ,the thinner the air ,the smaller the main jet should be. i'm at sea level and i'm running a 165 main ,pilot screw 1 3/4 turns out and it's fine !!

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  • Indy_WR450

Posted March 24, 2003 - 10:20 AM


If you have uncorked your pipe you may need to go to 170 main and YZ NDJN needle in the 6th position from the top. Search this forum for jetting advice. Make sure you hit the kill switch after being at full throttle for a while to read the color of your plug for the main jet. Idle jetting may be lean but you have to check that by letting it idle for a while before killing it.

  • Lon13

Posted March 24, 2003 - 01:17 PM


Adjust your fuel screw. I did, no more popping.

  • foursmoke

Posted March 24, 2003 - 04:27 PM


Hi ThumperWR450F!

Are you running stock pilot jet? I am 35 miles southeast of Boston, do you think I would be better off using a 165 instead of a 160 main? Should I check plug color 1st?

Thanks for any input,


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