If I JET my XR650R will it effect decibel rating for riding on streets?

9 replies to this topic
  • slider BRP

Posted July 11, 2007 - 04:10 AM


I just dual sported my new XR650R and wanted to JET it. Is that going to effect the decible level enough that the bike would not be street Legal. I understand that i dont have to take the bike to a "real" inspection place but i will be taking the bike to Germany with me in less than a year and i don't want any problems when i get there. All comment on this are welcome thanks for your help.

  • frogman

Posted July 11, 2007 - 04:37 AM


Is yours uncorked?

From what I've heard they sell the uncorked and factory duel-sported pig in Europe as a street legal bike.

  • slider BRP

Posted July 11, 2007 - 05:34 AM


no the motor is as stock as ever. but i wanted to get as much power as possible but still keep it in the limits of both the states an europe. So u think that i could uncork it and jet it. Put a new pipe on it and it should be good??

  • Denn10

Posted July 11, 2007 - 05:36 AM


its fine you need to jet it so you have the correct air/fuel mixture dont worry about Db

  • frogman

Posted July 11, 2007 - 06:35 AM


I'd advise you uncork and jet it correctly. If theres a sound issue, Baja Designs has the coolest silencer tip for the uncorked XR. It's easily removable and really quiet.
You also might check into getting an Edelbrock for your pig before you leave the US.
I tried every jetting combination in the world on the stock carb and could never get the bike to ride perfectly, but the Edelbrock completely changed everything. It worked as advertised.

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  • Denn10

Posted July 11, 2007 - 01:21 PM


you can jet it correctly for the area your in if you cant then you had another carb issue theres 10s of thousands of em out there with stock carb jetted just right.

  • slider BRP

Posted July 11, 2007 - 05:41 PM


ok guys thanks for your help good to know that i can unkork and jet and find a tip to get it quite again. thanks guys

  • pburke

Posted July 12, 2007 - 07:04 AM


as long as you don't make it backfire all the time it should stay the same :thumbsup:

  • BWB63

Posted July 12, 2007 - 12:40 PM


Some real crazy answers here. You must jet (set your air fuel mixture) right to what ever intake, exhaust system, weather, altitude that you have. These veriables must be taken into account. Your db is mostly set by the muffler you will run. (yes, other factors will contribute to more sound). Having a more free flowing exhuast will let you have more air flowing through you engine so, you can burn more fuel = more power. More air in, more air out you need more fuel. That would be bigger jetting. Most uncorked bikes run 68s pilot, B53E needle on the third clip, and 175 main jet. This is a bike with both the rubber and plastic pieces removed from the air box, smog pump block off, carburetor insulator block removed or the 16211-MBN-640 HRC insulator used, and Competition muffler insert 18317-MBN-640 or other slip on muffler.

Competition muffler insert 18317-MBN-640
Intake carb insulator 16211-MBN-640
#175 Main jet 99101-357-1750 178 Main Jet 99101-357-1780 180 Main Jet 99101-357-1800 185 Main Jet 99101-357-1850
B53E comp needle & seat 16012-MBN-641 or 16012-MBN-671
68s pilot jet 99105-MBN-0680


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  • XR680RR

Posted July 14, 2007 - 11:20 AM


Or you can use a stock tip drilled out with a 2" metal hole saw, instead of the HRC tip or slip on if you want to save money. It will keep the leagal spark arrester. Most do it this way and you will be right at the 96db sound requirement.

Like it was said, you jet for the right air fuel mixture not sound or power.
If you make the engine take in more air you increase the fuel (jetting) to have the right air fuel mixture, making the fuel mixture detonate correctly. If the bike is to lean the bike will run hot and bog, to lean and you will ruin your engine. To rich and the bike will run soft, flatten out, way to rich and it won't run right at all. Running a more open muffler (louder) on a corked bike not jetted will run the bike super lean at sea level. Un-corking a bike and not jetting will run hot enough to ruin the engine. Add a open exhaust system to that and the bike shouldn't run, if it did it wouldn't for long. 14.5:1 air/fuel mixture is perfect but, in an engine it is known to run much better at 13.5:1. Our bike with a stock carb. runs best a little rich on the pilot and main, having the needle real close to spot on or lean. This helps get rid of the off idle bog that the carb gives while biulding up vacuum.

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