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jazzeyb

jet or new carb

10 posts in this topic

Couple of questions..

The original owner stated that the carb had ben jetted on my bike...

What's the best way to tell?

And without any additional engine mods, what kind of performance gain am I looking at by switching to an Edelbrock carb.....

thanx... JaZz :)

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How does it run? Has it been uncorked? I don't have my manual with me, but I believe the main jet is #125 as shipped. By uncorking, I mean check the following:

* Snorkel inserts from airbox have been removed

* Intake manifold passage consumes full width of manifold - there is no rectangular-shaped restriction

* Bike does not sound like an air compressor when running

* Bike does not ride like an XR250 that you never have to shift.

There are several links to more detail of uncorking available.

My guess is, the bike is uncorked; if it's not, you're in for a real treat.

Congratulations! :)

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Best way to tell if your carb has been jetted: Remove the Drain Bolt from the bottom of the carb bowl. Now you have access to the main jet, remove it and read the number on it. If it's a 125, it's stock, if considerably larger number, such as 170 or 175, then it's been jetted.

But don't trust just that. Check the airbox, see if the snorkel and restrictor plate are gone, and check the carb intake boot and make sure it's straight through (40mm opening). Also make sure the exhaust tip has a 40mm opening.

the stock opening is 20mm I think.

As for how much more power the Edelbrock carb will give you, the answer is not much if any at all. The reason people switch to it is for better all around performance, and it won't burble or stall when you jump the bike.

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Just get a new carb, you are going to get it anyway, why wait?? You can dick with jets and throttle hesitation and, if you drop the bike once in a while, flooding/ starting issues till you are blue in the face. Eventually you will buy the EBQS. No more jets up to 10k feet, no more starting, or Throttle hesitation, and it will run upside down. Call Barnum, this is a no brainer. You spent at least $4k on the bike,drop the extra $400 to run it right.

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My '01 XR650L has the snorkel in the airbox removed, stock exhaust , K&N airfilter, stock slide needle shimmed up 0.030 inches, vacuum holes in the slide drilled to 5/32 of-an-inch, and has a 158 main jet and a 55 pilot jet. The tab is ground off the float bowl so the pilot screw is fully adjustable.

If the pilot is out more than 2.75/3 turns, the pilot jet needs to be richer. If they sell gasohol in your state, your jetting will need to be richer.

-Dave

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I bought my L with 290 miles on it, so I am assuming it had the stock jetting, because it ran like [@#$%&*!].:D The main jet size was 152, and the pilot jet size was 50. I first tried a 55 pilot and a 155 main, shimmed needle, desnorkled, slide drilled, UNI filter, and a XR's Only pipe. It dynoed at 38.3 hp's and I was still getting around 42 mpg. I couldn't keep the front wheel on the ground. I have since put a 162 main in, and put the stock pipe back on. My top end is good, but I lost some bottom end. I might throw the XR's Only pipe back on, because I loved the way it revved up to RPM's so fast. :D Check out the xrlug user group. There is a lot of good info about the L there. :)

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