This was provided by Lancer and is based on the stock Mikuni BS40 carb. These are basic guidelines that work just fine on my Amal Mk2 also. Remember that each bike/carb/environment can be a bit different and 1.5 turns for you may be 2.25 turns for someone else. Don't just copy; tune yours.
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 down and 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 example...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.
Pages: 1
