O.K.,,, Short answer,...
I would start with a 152 main/55 pilot and 2/3 spacer mod... drill out the idle mix screw and set to 1 1/2 turns out.
Then see from there...
Instructions on spacer mod are in the Tech section...
Stock is 145/52 on new Us model...
Do make sure that your carb is in good working order before you make any corrections from there, or you will be correcting problems with jetting and get everything out of wack... it's a simple carb and easy to clean and work on....
and Lancer is our resident expert tuner,... so consider his advice on that muffler... Sportster muffler conversions are very popular here, and they add a little performance and look and sound nice. Some people do run open drag pipes, but they are more for style than performance... you loose a lot of torque, but they will drive the neighbors crazy, if you're into that...
Here's some general ideas on tuning...
Quote:In general...
thinner air = go leaner
hotter air = go leaner
more humidity = go leaner
higher altidude = go leaner
thicker air = go richer
cooler air = go richer
less humid = go richer
lower altitude = go richer
Barometric pressure effects jetting in a big way, humidity, air temp, and elevation. Some places have extreme variations in barometric pressures and if you live there, your pipe will blue. I live in the high desert and temps can change 40 degrees f in a couple hours, humidity can vary wildly too. No way to jet for that.
A good indicator of overall jetting is the weather...if popping/backfiring increases on humid days, or at higher elevation, that indicates rich....less popping at those times indicates lean.
To test the main, accelerate from 30 or 40 mph, in 4th or 5th gear at full throttle for several seconds, then reduce throttle by about 1/8,...if power increases for a second, you are lean on the main jet. Go up one jet size and test again.
#4 teflon washer from Ace hardware is exactly 2/3 thickness of the stock spacer and will fit perfect. It comes in white or black. It is just what you want. One and only one. It will measure .066",... stock is .1"...