Jetting for XR650L


4 replies to this topic
  • pjpoo

Posted January 22, 2007 - 09:09 AM

#1

1994, smog equipment removed, pod filter (sock type uni), white bros full exhaust (not sure exactly which model), mostly run at 2500'

PO says he has a 58 main jet in the bike. Recommended a 50 main jet with a long pilot.

I do know the bike stumbles hard in the mid-range and a little in the low range. Backfires and kicks out smoke on downshifting. It can completely die on deceleration. My supermoto also runs just as bad at sea level and smells rich behind me, or so I'm told. :lol:

Recommendations? A baseline would help as I've never done this before.

  • cleonard

Posted January 22, 2007 - 11:15 AM

#2

1994, smog equipment removed, pod filter (sock type uni), white bros full exhaust (not sure exactly which model), mostly run at 2500'

PO says he has a 58 main jet in the bike. Recommended a 50 main jet with a long pilot.

I do know the bike stumbles hard in the mid-range and a little in the low range. Backfires and kicks out smoke on downshifting. It can completely die on deceleration. My supermoto also runs just as bad at sea level and smells rich behind me, or so I'm told. :lol:

Recommendations? A baseline would help as I've never done this before.


I reccomend that you put the air box back in. Removing it really changes the required jetting a lot. Generally with a pod filter you can gain at the top end, but the low and mid suffer. It is very difficlut to get a CV carb to run right on a pod style air filter. They really need that slight vacuum that the airbox provides.

I think that you have the jet numbers wrong. The stock jetting is a 2 digit jet for the pilot and a 3 digit jet for the main. The main is 158 not 58. The other is the pilot. With a pod you will need to go several steps up on both. With a POD filter the stock needle will be way way too lean. Shimming the existing needle will help, but it will not be enough. You are sure to need a different richer needle to get the mid operating correctly.

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  • XR650L_Dave

Posted January 22, 2007 - 04:22 PM

#3

55/158 is the stock-exhaust mostly-stock-intake baseline.

At a guess 58/160 wouldn't be a bad start for a pod-filter setup, would maybe even be too lean.

I'd go in there, find out what jets/needle are actually in there, make sure the slide is drilled while you're at it (assuming stock CV carb).

Dave

  • cleonard

Posted January 22, 2007 - 05:28 PM

#4

I would expect a lot larger changes. I tried pod fileters on an old Honda twin. The stock jetting was a 68 pilot and a 112 main. I had it up to a 88 pilot and a 135 main and it was still too lean. The mid range sucked too. Good luck getting it to work right.

A standard carb will help a lot in trying to get it to run right.

  • pjpoo

Posted January 24, 2007 - 10:06 PM

#5

I was thinking of pulling the carb apart tonight, but figured I should check out a manual first. Which means I have to buy one :ride:

Also, flatside would be much easier to tune from what I'm reading, right? What size for the L model? Should I get a jet kit just so I have my tuning options up front?





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