XL600R Jetting

21 replies to this topic
  • davek18

Posted December 30, 2007 - 04:18 PM


What part of Washington state? I am over here on the dry side just south of Pullman.
I had not messed with slow jet at all since idle quality was good and the mixture screw was turned out about normal. But I was curious so I came down to the shop today and pulled out the slow jet to see what size it is. It is a 45, which got me wondering since everyone else is talking about 65's. I looked it up on Babbits online oem lookup and 45 is standard for 85-7 XR600 carbs. I even pulled the slow jet out of a spare set of xl carbs to look and it was 65.
I do know that the needle and needle jets are different between the XR and XL, maybe that is worth pursuing? They are still available, I bought a set from Babbits. Occasionally XR carbs pop up on Ebay too.
It has been my experience that fooling with slow jets doesn't do much. Anytime I have gone much bigger on a slow jet it is too rich to idle properly.
I think slide cutaway and needles have much more effect on low end than pilot jets and my theory is that by speeding up the secondary carb you actually emulate a lower slide cutaway since the secondary has little or none and it is now coming on above idle. besides the secondary carb has no slow jet at all anyway so my speeding opening should have caused a horrible flat spot if it relied on slow speed circuit for initial enrichment. I wouldn't go much richer on the slow speed if I were you. Maybe a 65 but no more, if the idle mixture can be adjusted it is probably ok.

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  • monkeyman7-11

Posted February 26, 2014 - 02:26 PM


Thanks, now we are getting somewhere. How do you guys modify your airboxes? On all of my bikes I drill 1/2" holes in the airbox cover under the side cover and then stick air filter foam on the inside of the airbox cover. I figure if I am facing serious water, I can always stick my spare undrilled cover back on it or slap some duct tape over the holes. But the side cover always keeps water out to the point that I have never needed to cover the holes. Except maybe when I lost my XT in 6' of water. But somehow I don't think my airbox mods mattered on that one. :confused:

Well I've just got my hands on an xlr600 with 20l dakar tank (happy about that even with the pin holes requiring the lot to be por15 sealed)  given the snorkel is pointing into the rear wheel throw off my first thoughts were to loose it and although I really don't intend to loose the filter without running sealed tubes up under the tank to the steerer the box top is going to be the highest point water wise  and will all ways be     Im personally considering once the snorkel is gone giving it an Inch cut rearward for more air and whacking a 150 main into left carb to boot with a couple of small needle shims and see what that does ......It's got an aftermarket high flow pipe anywho and its not exactly difficult to test via running with side cover off before actually cutting into the box my thoughts are with the extra air flow and secondary readjusted for correct opening time with the larger standard jet in it .... It should be about right for max gains ...... intending  to put smaller rear gear on too or bigger front haven't looked yet but to use the extra torque and power without compromising range of tank ad give a little higher top end as well I reckon that may do the trick ???        I do realise this thread is old before someone pipes up with that LOL    any accurate info on up jetting airbox mods and such will be much appreciated thanks :-)     

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