Here's a quick trick to know which way to turn those fickle air fuel screws just by looking at any carb body! #shorts Subscribe for the upcoming complete series on carb components and functions!
I think this is the only best explanation about the meaning of adjustment on carburetor I have search for long on utube. thnx for ur good summarized work
He got it backwards unless he is saying it wrong. A carb adjusts air not fuel, so you can only run rich/lean on air. He could get peoples engine blown up doing it the wrong way!
@@zovards2089My carb only has one screw on the engine side at the bottom. If I loosen it is richer and tighten leaner? I can't find the sweet spot between both. it idles well but sometimes it does little backfires when downshifting.
It had been twenty plus years since I had been on a bike!!! I ride two strokes and my bike was idling really really high. I had changed the reed cage and reeds and couldn’t figure it out. This video told me exactly what I needed to know and I thank u for this video!!!
Not always the case. Best way to tell is to remove the screw completely and if it has a fine point then it is a fuel screw. If it has a blunt point then it is a air screw.
@@Jursaw don’t those use knockoff keihin carbs copying the PD series from Honda’s smaller XR/ CRF’s? They should have air adjusting screws on the airbox side of the carb.
Brother! I have been dealing with a lack of fuel issue for the last 6 months i kept backing the screw out.... because of this i know i need to screw it in... thanks so much!
Mine is on the outside by the intake and i loosened it to the very end and oh my word the amount of engine response and power it suddenly had. The bike used to stumble whenever im taking off it would only run about right when im at about 2500 - 3000RPM but now its so smooth and it pulls hard im so shocked
Ive heard that air screws are more sensitive to adjustments than fuel screws are. Would make sense since that the perfect ratio is 14.7:1. Seems like adding more or less air would have more dramatic effect than fuel would
Thanks man I always knew that i needed to use that clscrew to adjust the carb but for the longest time i couldnt figure out witch way was more fuel and witch way was less fuel
Nice job on the finding. Will be useful for my next project, I just need to clean up a gas gumed carburetor from Honda shadow. Technician said will cost me 5-600 to clean on the bike now.
very simple Great. My carburetor has 1 screw with a hole is it the second screw that you are talking about? 1 is for air-fuel mix another is for accelerator/ throttle increase and the 3rd one is with a hole what is that? Slow jet or something. but I wanted to confirm as there are 3 screws which one I need to adjust? I adjusted air-fuel mix screws as you said but when I try to adjust the screw that has hole in it as my screwdriver goes on the hole my car shut off then how can I adjust the screw with hole?
All my 38mm keihin 2 stroke carbs have the air screw on the left side of the carb with the air screw on the right hand side, which would be the air filter side and not the engine side right?
Yes, what you describe is common among 2 strokes. With the mixture screw on the airbox side so they control air (out is more air = leaner, in is less air = richer).
Great question! I see this installed wrong all the time. It goes: needle-spring-washer-oring. You can remember it by thinking of the job the washer does, it protects the oring from the rotation of the spring when tighten/ adjusting.
I have the plastic screw heads on TM40’s on my Snowmobile and I went from 1.5 turns (spec) to 2 turns thinking they controlled air. Now it floods out at idle and is really hard to start when warm. I guess those screws control fuel and not air on the TM40’s. Can you confirm this? Thanks for a great video. Subscribed.
Great idea! In the meantime in short, it's a tough call because they both have advantages. VM is cheaper/ easier to tune, but TM has a better performance potential.
2 and a half out fuel 1 and a half air out when you tighten them don't tighten them tight you will damage them so go slowly,ride on, the pit bikes 2 stroke is different
@@PinnedTTR125 They most certainly do have an idle adjustment screw. But on that carb it’s not the screw in the middle. That is actually not a screw, it is a guide for the throttle slide. You can’t (or shouldn’t) move it even though it looks like a flat head screw. The mixture screw is on the engine side under the carb (meter’s fuel), it may be covered by a little plug you have to remove.
@@oneupmotogarage I had to move it the other day because of a adjustment to my air box that caused it to backfire and idle low and I turned that screw and both problems where fixed
It won’t run well! Usually if you’re more than 3-1/2 turns from seated you’re too far out. And if you’re less than 1/2 turn from seated you’re too far in. If it needs to be outside of those boundaries, your pilot jet needs to be bigger or smaller.
One isn't always better than the other. It's a ratio and a matter of finding the best mix. Usually start at 1.5 turns out for these VM round slides. And then tighten loosen from there in 1/2 turn increments to find best idle/ off idle response.
what carb or bike are you dealing with? All carbs have an a/f screw somewhere. Sometimes they're on top, bottom, left or right side. If it's a street bike made after early 80's the screw will be covered by an aluminum plug you have to drill out to access it.
My fuel metering screw seems to do nothing on my recon 250 I can run it all the way in and out and doesn’t do anything, I have the throttle needle clip on the 2nd to last slot and I still getting popping when I rev and let off the throttle
The screw in the middle is the idle adjustment, it directly raises and lowers the slide. The stock LT80 carb does not have an air fuel mixture screw. Which is fairly rare. But aftermarket options for it do. The stock carb works well without it so I'd say don't sweat it.
The screws can be any number of places on the carb. Top, vs side, vs bottom. Either way just note when looking at the side of the carb, is the screw closer to the engine or closer to the airbox- relative to the carb’s slide? Usually ones on the top and bottom are fuel metering screws, and are closer to the engine.
