2005 Honda CRF 80 F carb adjustment I need to adjust the carb on my bike but I don't know what the adjustments are. I took apart the carb and cleaned out the jets and I got a little tiny hole in the low-end jet (smaller jet) but I don't know if it is big enough for enough gas to get through. The bike will run with a little bit of throttle but if I let off the gas the bike will die and it doesn't have instant throttle response. I need the adjustments for the air and throttle (knobs on the side of the carb) because they are just all messed up from the guy I got it from. Thanks, Kyle @

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30 Nov, 2017

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    Solved this issue
  • 85min
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Hi, Kyle it should be noted that the "AIR FUEL" mixture screw adjustment "ONLY" manages your idle and has no effect on any other circuit also any intake leaks must be repaired before the A/F adjustment procedure can be performed otherwise you will never obtain a proper idle and you will waste a lot of time chasing the impossible. The A/F mixture screw's purpose is to fine tune the fuel charge entering the combustion chamber. The following applies to both 2 and 4 stroke engines:
1. The mixture screw may be sealed at the factory with a Welch Plug please review the following video for removal.
https://www.youtube.com/watch?v=wAXcksgvDkM
2. The mixture screw manages a range of 3 complete 360-degree counterclockwise turns from the bottom/closed position.
3. The mixture screw should have a spring and o-ring for tension and sealing integrity.
4. Turn the mixture screw clockwise until it gently bottoms out, this makes the fuel charge very lean and the engine should not idle if it does then the pilot/idle jet is too big and needs to be replaced with the next size smaller.
5. Turn the mixture screw 1 and 1/2 turns counterclockwise to establish a baseline for starting the engine.
6. To fine-tune the idle circuit, adjust the mixture screw 1/4 turn in or out to achieve maximum idle RPM, wait 15 seconds between each adjustment for the idle to settle.
7. Never go past 3 full turns out this will make the fuel charge rich, foul plugs, and produce black smoke out of the exhaust, if the engine RPM keeps increasing past 3 turns the pilot/idle jet is too small and needs to be replaced with the next size larger.
8. After achieving maximum idle back out the mixture screw another 1/8 of a turn then adjust the throttle cable idle stop screw to 950-1050 RPM.
9. This procedure works great on 99% of all engines, for the 1% that demand a more robust throttle response on aftermarket monster fuel delivery systems additional tweaking outside the box may be necessary.
For more information about your issue and valuable "FREE" downloads that you will need for viewing or printing please click on the blue links below. Good luck and have a wonderful day.
Honda CRF80 Carb Adjust Mixture Screw Mod
2007 Honda CRF80F Motorcycle Idle Speed Adjustment Attempt CRF80F CRF100F service manual repair 2004 2013 CRF80 CRF100 Download... $15
https://www.partsfish.com/page/oem-parts-for-honda
HONDA CRF80F Owner Manual
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