armyofda12mnkeys Posted January 28, 2010 Share Posted January 28, 2010 I was curious... I was gonna test my fuel/air mixture with a colortune, but I was curious... in many online sources, they say this is always done via the idle mixture screw (sometimes known as pilot screw i think), and you need a small flat head screwdriver to get at it... had a few questions... 1. On an 1978 XS400, this is simply the thing underneith the seat area that i can adjust with just my finger (don't need a screw?), right? Ive used this to mess with idle settings before so I assume it is. 2. Assuming direction-wise that I'm sitting on my bike + looking down 'into' the seat... turning it clockwise leans it + counter-clockwise enrich's the fuel/air mixture, right? So when the bike is off, I would turn it very lightly clockwise until it is set, and then turn counter-clockwise to goto the manufacters setting (or 1 turn out if dont have that setting), and then try 1/4 turn increments until Colortune gets bunsen blue color. I've adjusted the fuel/air mixture by rpm's/sound of the '78 XS400 engine usually be4 buying Colortune ... which usually to me sounds good at about 1500 rpm's. 3. Just curious what the manufacturers recommended setting is for the rpm's + how many turns counter-clockwise from when the screw is set is the manufacturer's setting if available. 4. In the Colortune manual, It says when too little air is in the mixture, not enough oxygen to complete burning process so some CO (carbon monoxide) not converted to C02. + some unburnt fuel may be in the exhaust. and If too much air in mixture, more difficult to ignite + "misfiring" may occur + unburnt fuel in the exhaust gas will rise. So both scenarious, unburnt fuel may be coming out of the exhaust right? [which may make a 'shooting sound'/quick flame come out of the exhaust?]. Just asking above question to also try to figure out a possibility why my buddies Honda CB loses gas quickly, backfires out of the exhaust, (and also seems like gas sometimes coming out of his exhaust, but not sure on this one). Thanks guys!, Ari Link to comment Share on other sites More sharing options...
Moderator drewpy Posted January 28, 2010 Moderator Share Posted January 28, 2010 rpm's = 1200 2.5 turns from LIGHT bottoming out. its an air srcew, so screw in richens, out weakens ( well it does on mine!!) Link to comment Share on other sites More sharing options...
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