thumperclone wrote on 12/31/69 at 16:00:08:carb theroy 101 not sure if its this site or not tech section.. on thing ive noticed tho most carb postings are from(dont get offended) low landners,down streamers,
one MUST take altitude(and for sluggos sake attitude)
into consideration.. not to mention humidity,BM pressure
grade of fuel,twistness of the right wrist etc etc...
the most one can hope for is(nervona)a happy medium when carb tuning..she'll run one way at 2 am and another at 2 pm thats the nature of the beast.. 8)
And that's why you use the tuning process instead of, for instance, just the same number of turns as someone else. If your operating climate changes significantly, tweak it. I'd bet you'll be able to find a set of jets that works in most, if not all, of your riding conditions. Then it's usually just a matter of having a small screwdriver with you. My point is that it's the tuning process that can be carried from bike to bike and from locale to locale - not the turn count or jet size. Below is a quote from Lancer and it pretty well sums it up.
Quote:-start with the pilot adjusting screw at 1.5 turns out as a reference point, and count as you turn in and out so you always know where you are during the process. Everything is done and referenced in the "# of turns out".
-turn idle up a little so you have a smooth fast idle
-turn pilot adjusting screw "in" until engine begins to slow downand note the # of turns out
-turn pilot adjusting screw "out" until engine begins to slow (it will speed up initially then go down) and note the # of turns out
-then set the pilot adjusting screw in the "Happy middle" of those two positions
-after the pilot circuit is happy, turn the idle adjusting screw back down for the idle you desire.
*for ex...if the turn in setting was at 1 turn out, and the turn out settig was 3 turns out, then the happy middle is 2 turns out.
**Turn slowly as you do this, no more than 1/8 or 1/4 turn at a time...then pause and wait 5 seconds or so in order to give the engine time to adjust, then turn again if necessary. If you have a tach, then you can set the pilot adjusting screw by just tuning for max rpm, then set idle speed.
***If after you have finished this process, the pilot adjusting screw is 2.5 -3 turns out, then you definitely need the next larger pilot jet. For myself, if I go over 2 turns out then I go up to the next size pilot jet.
When the pilot is properly adjusted, and assuming there are no exhaust leaks in the system, you will not have any backfiring. It is normal to have some mild crackling and popping on brisk-hard deceleration, but there will not be any backfiring.