First step in the uncorking process

13 replies to this topic
  • glabudde

Posted October 21, 2005 - 06:20 PM


Just got a new 2005 650r - spent a bunch of $$$, can't get away with spending much more right now. What is the first step in uncorking one of these monsters? There is plenty of power for my riding skills, but I have heard that the operating temp will go down, which - should prolong motor life?

Would eventually like to go all the way, but need to start small (<$200) due to budget constraints (i.e. wife :banghead: ).


  • dirtrider13

Posted October 21, 2005 - 06:43 PM


Rejet. I went with a 170 some go 175. Take off the smog pump, backfire screen and manifold gasket. Throw them away you wont use them again. replace the backfire screen with one with bigger holes. The maniforld gasket will be a full circle instead of a reduced oval. Then drill out the exhaust tip to open the exhaust flow. You will gain about 15 plus hp's. Also will keep the beast from overheating. This is the cheapest way there is to gain the horses and make it run like the BRP. Also replace the air filter with a Uni.

  • maddmickey

Posted October 21, 2005 - 06:52 PM


Uncorking the pig is trickey that way because everything you do complements the other. In other words if you get more air in (airbox holes,unrestricted intake) you need to get more air out (HRC tip, or aftermarket pipe) and then you need to rejet for the higher airflow. If it were me I would save my money for the whole process. Meanwhile get out and enjoy your new bike!! :banghead:

  • BRP-rider

Posted October 21, 2005 - 07:10 PM


So if you replace an air fliter with an aftermarket low restriction, high flow air fliter. You would need to put an aftermarket muffler on to allow more air in/out of the engine.

In doing this you would then need to rejet the carb? :banghead:

  • maddmickey

Posted October 21, 2005 - 07:14 PM


if you drill out the exhaust tip you can probably uncork for under $200. I forgot about that until i seen dirtrider13s thread.

  • maddmickey

Posted October 21, 2005 - 07:30 PM


You might have got me there! You can probably do small things, like a high flow filter and gain performance without changing exhaust or rejetting. but at some point when you start adding higher performance parts you will have to rejet.

  • big t

Posted October 21, 2005 - 07:32 PM


Check out Check the link to left about making the xr650r run right. I think it cost me about $30-40 for the jets, carb boot, and a 2" hole saw for the exhaust. If you want to save more money you don't even have to buy the opened up version carb boot you can just cut the stock out.

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  • BRP-rider

Posted October 21, 2005 - 07:34 PM


If you change the muffler and the airflilter, both, you will have to rejet, correct? :banghead:

  • qadsan

Posted October 21, 2005 - 07:44 PM


Check out for all kinds of good info on your new bike :banghead:

  • babbs

Posted October 22, 2005 - 05:36 AM


Get a new air filter, rejet, cut out the restrictor in the intake boot, and drill out the exhaust. It will cost you about $50. And will keep you smiling for a long time. There is a whole lot of info on the net (, and Borynak's site) most of the people who post short answers will give partial answers, but a well constructed web site will answer all of your questions and give explanations.


  • Ramcc4x4

Posted October 24, 2005 - 06:48 AM


Don't forget to replace the 65 pilot jet with a 68s!!

  • al_piv

Posted October 24, 2005 - 06:55 AM


Check this out --

  • Winkel

Posted October 24, 2005 - 08:26 PM


I did mine for about $15. I bought the jet kit on e-bay, 68s pilot, 170, 172, and 175 main. You can drill out the silencer with a small bit, a bunch of holes, a screw driver and hammer ( I made a wooden holder to keep from smashing it.), and a dremel to smoothe the edges down. Don't worry about the stock air filter for now if money is an issue. I did mine in a few hours, and the difference was WELL worth it.

Good luck,

  • wr450fyamaha

Posted October 25, 2005 - 08:42 AM


If you change the muffler and the airflilter, both, you will have to rejet, correct? :banghead:

yes, more air flow, more fuel.

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