24mm Carb which Jets to use

[Miker85085]

I just removed the standard air box and replaced it with a K & N style filter, also I replaced the exhaust with a performance stainless steel. That being said I have a standard 24mm carb on a 157QMJ engine with standard out of the box jets installed. I have read that now with more air flow you should not run too lean and replacing the slow and main jets to a larger size would be a good idea. I live at 1100' elevation and very warm weather most of the time (Arizona) what do you think if I install a #38 slow jet and either a #115 or maybe as high as a #130 main jet. Any words of wisdom would be appreciated.

[rks]

Jetting is a trial and error process. I am no expert, but my 157QMJ powered scooter has a bit over 6,150 miles on it, and the original spark plug is still going strong. No erosion to electrode, or ground strap, insulator is a nice tan color, and my last tank of fuel delivered 89.4 mpg. I run a K&N filter, stock exhaust, and a 115 main jet. I live at 1,610 ft above sea level....all scooter operation is between 550 ft and 2,000 ft.

I don't think you will need to change the idle jet, an adjustment to the a/f screw should take care of that end of the spectrum. You are in the ballpark with the main jet size. I suggest you get an assortment pack of mains, no smaller than 112.5, up to maybe 125. Think you'll find that somewhere between 115 and 120 will be best.....