Yeah I have always worked my way to the #73 / .061mm jet size
I clean my plug well, go on a 3-5 mile round trip and then after engine has cooled a bit I pull the plug and check the color to make sure it's not too lean of fuel/oil.
I can normally tell just by the way it is running if I'm about where I need to be, if I get to much 4 stroking it is a good sign of a rich mixture and if I have room to move the needle clip up a notch I will do that before I resize the jet again, but if I end up with the clip in the very top groove and still have a rich condition, I will heat the jet with torch again to refill the jet and then I will move down in drill size one time and then repeat this entire proccess until I get a nice light chocolate brown plug reading and the 4 stroking is normally where it needs to be at this point, ( slight off & on under low load conditions and zero under power and up inclines) this is how I tune mine and they run smoothe and produce good responsive power at a twist of the throttle, just the way I like it...........Yea Haw.......! LOL!
Would be nice to have a Tillitson Carb set up on one of these engines so it would be easy to adjust for each day by just a little tweaking of the air/fuel mixture.
I'm not an expert on all the 2 stroke stuff so I have been unsure about whether or not a diaphram type carb like the Tillitson's will work on these open port 2 smokers without the puffing back that these engines do damaging the diaprams in the carb. I know weed wackers and chainsaws use the little Walbro & Zama carbs with no issues but not sure about the Tillitsons on a China Girl, if anyone knows in facts on this matter put-em out here cause I would like to know.....oooop's a little off topic here but the tuning stuff brought me around to this question I guess.....
Originally Posted by Pablo
I always have to go .64mm/.66mm/.68mm
#73 wire gauge drill bit = .61mm