My 1986 shadow VT500 has been running rich and fouling the plugs so I wanted to adjust the air/fuel screws but I'm not sure which ones they.
If the mixture adjustment screw is on the back of the carburetor (Air filter side, before the carb venturi - like most two stroke motorcycles) then it's an air screw (and controls the amount of air). Screwing it out will lean the mixture. Screwing it in will richen the mixture.If the mixture adjustment screw is on the front of the carburetor (Intake manifold side, after the carb venturi - like most four stroke motorcycles) then it's a fuel screw (and controls the amount of fuel). Screwing it out will richen the mixture. Screwing it in will lean it.
I accept the convention, screw on engine side, FUEL SCREW; screw on air filter side, AIR SCREW.The Kawasaki Logisticiam-In-Charge of Part Nomenclature may not agree; the obvious fuel screw in their Keihin CVK carburetors is labeled, 'Screw, Pilot Air.' Translation error from the Japanese? While I think the screw regulates an actual mixture of air and fuel admitted from the pilot circuit, counterclockwise rotation fuel-enriches the idle mixture, clockwise rotation fuel-leans it.To me, it's a FUEL screw! If the mixture adjustment screw is on the back of the carburetor (Air filter side, before the carb venturi - like most two stroke motorcycles) then it's an air screw (and controls the amount of air). Screwing it out will lean the mixture. Screwing it in will richen the mixture.If the mixture adjustment screw is on the front of the carburetor (Intake manifold side, after the carb venturi - like most four stroke motorcycles) then it's a fuel screw (and controls the amount of fuel).
Screwing it out will richen the mixture. Screwing it in will lean it. All wrong, above.Old thread, but here goes, for constant vacuum carbs, flatslides.Adjuster screw closest to airbox (side, bottom, whatever) it is a FUEL screwAdjuster screw on engine intake manifold (side, bottom, whatever) it is an AIR screw.Can't believe so many got it wrong, no offense, just needs to be clarified.
Need further proof, looks at SUDCO's, Mikuni, Keihin's own tuning handbooks, or read the part descriptions.The only way to get more fuel through the carb of an pilot air screw engine is to enlarge the pilot fuel jet which is what limits/sets the flow of liquid; all you are doing is adding/removing air from the pilot circuit mixture when you turn the adjusting screw. All wrong, above.Old thread, but here goes, for constant vacuum carbs, flatslides.Adjuster screw closest to airbox (side, bottom, whatever) it is a FUEL screwAdjuster screw on engine intake manifold (side, bottom, whatever) it is an AIR screw.Can't believe so many got it wrong, no offense, just needs to be clarified. Need further proof, looks at SUDCO's, Mikuni, Keihin's own tuning handbooks, or read the part descriptions.The only way to get more fuel through the carb of an pilot air screw engine is to enlarge the pilot fuel jet which is what limits/sets the flow of liquid; all you are doing is adding/removing air from the pilot circuit mixture when you turn the adjusting screw. Click to expand.I've only been wrenching professionally 30yrs, worked with Factory Pro as they developed their jet kits starting in the late 80's, spent more time dyno-tuning CV (and other but mostly CV) carbs (at Factory) than most anyone I know. And we've met, many years ago George. Call SUDCO, call Marc Salvisberg (owns Factory Pro) and ask them. Read 's endless CV LC8 carb tuning exercises and view the technical drawings of our carbs.
But don't take my word for it.I'm just trying to stop disinformation here on OC about a little screw so Inmates don't act on screw settings in the exact opposite way it does based on someone being confused. I've only been wrenching professionally 30yrs, worked with Factory Pro as they developed their jet kits starting in the late 80's, spent more time dyno-tuning CV (and other but mostly CV) carbs (at Factory) than most anyone I know.
And we've met, many years ago George. Call SUDCO, call Marc Salvisberg (owns Factory Pro) and ask them. Read 's endless CV LC8 carb tuning exercises and view the technical drawings of our carbs. But don't take my word for it.I'm just trying to stop disinformation here on OC about a little screw so Inmates don't act on screw settings in the exact opposite way it does based on someone being confused. Click to expand.Maybe the issue here is you are referencing CV carbs in your response-CV and flatslide in your earlier. My 950 KTM was the only recent experience I had with CV carbs.
Those and the other carb'd LC8s I am familiar with, are downdrafts and somewhat unique as I recall. I believe those screws were physically under the carb. Since the intake side is the top, they are on the motor side. It is long gone and I honestly dont remember if they were fuel or air. But I have done a whole lot of work with Keihin PWks on and the like on 2 strokes and FCRs on most performance 4 stroke dirt bikes. They are per my description.
Different for CVs???