Carb tuning/air screw - Kawasaki KLR 650 Forum
1987 to 2007 Wrenching & Mods For maintaining, repair or modifications of Generation 1 KLR's. 2007 and earlier.

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post #1 of 4 Old 12-23-2018, 03:01 PM Thread Starter
1st Gear
Join Date: Jun 2016
Posts: 16
Carb tuning/air screw

Ok this subject has been covered a 1000 times. I let me bike sit to long and needless to say taking carb off shortly.
When it was running overall performance good but it felt like a very very slight pulse/hesitation when cruzing around 60MPH. At least I think I feel it. My set up is Lex pipe air box drilled carb screw 2.25 best I can feel. Dynojet needle with 5 grooves clip on second slot one small washer under and a 142 main jet. Stock pilot jet. I know the Honda guys replace pilots left and rt but it seems the stock KLR pilot is good. Its my understanding the mid throttle cruzing the pilot circuit is running before you get to main jet. May larger pilot? another .25 turn on the air screw ?? Ill take any input. Meanwhile out to play with smelly gas I should be ashamed.

Cheers Brad
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post #2 of 4 Old 12-24-2018, 09:40 AM Thread Starter
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Join Date: Jun 2016
Posts: 16
Well I took it apart and as usual the pilot jet clogged. Orifice so small it does not take much. Anyways left the 142 main in and replaced the pilot with 42 instead of a 40. Set the mixture screw to 1.5 turns. Took it for a slow spin around the block [note it was near dark and chilly out side so shorts t shirt where no good] and feels quite peppy. Ill say the cool dry air makes up for part of that but the short test ride and one hard throttle down the drive to the house feels like a improvement in performance. Lets see.
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post #3 of 4 Old 12-24-2018, 01:08 PM
Join Date: Nov 2009
Location: Lander, Wyoming
Posts: 6,270
Your changes may work for you. But how well did it used to run before the pilot jet got restricted? Maybe ALL it needed was Only the proper cleaning?

If a proper cleaning didn't cure the issue, then I would have pondered other options, including yours.

For a mid-range issue, one might have concentrated on the mid-range needle. As in possibly Remove the 1/2 step washer under the needle clip & move the clip to #3?

Time will tell, but we also need to consider Normal operating ambient air temps instead of winter temps.

Modify at "YOUR OWN RISK"!

Still riding my 1987 KL650-A1. 85,000+ miles & counting
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post #4 of 4 Old 12-24-2018, 05:25 PM Thread Starter
1st Gear
Join Date: Jun 2016
Posts: 16
Thanks for the input. Yes on the cleaning but I had already ordered a jet from Rocky M including a 145 for the main also. I rinsed out the passage ways with carb cleaner but they where clean. I did not feel like messing with the jet. Pretty obvious put it up to the sunlight and no go. Compare to a new one and you can see through it. I had a to search quite a bit to find out what needle I had. But luckily I found some chatter on the forum and a archive with some info stating 5 grooves. So Im confident I have a dyno jet and Im using stock jet numbers. I spoke with E Mike once and his comment was a 145 might be the way to go but I commented on adding a washer to the 142 and he thought I was on to something and the 142 is based on some info gathering through the forum. So Ill stick with the 142 for now I agree simply reclocking
the clip to the 3rd slot might help. And yes the outside temp dense and cool does not compare to summer heat in Tx. Have not had a chance to steady ride around 55 or 60 to see if I have improved on what I think is lean spot. I have no throttle lag and when I nail it in first and the front wheel comes off the ground. Did not do that
before but I have not run it much in the air conditions that I Have now. I want to get a ride for a fuel consumption test.
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