Night and day, the difference between the stock carb and a Dellorto (a real carb). Now my bike idles smoothly and I can set it for a lower rpm for idle without fear of it dying. From idle to top speed the mixture is just right and lets me accelerate without hesitation or sputtering. What I recommend is the 12mm SHA carb which is the correct size according to the Dellorto manual on page 7. Now the negative side of the story: its web page says it comes ready to fit onto the 19mm intake pipe. NOT. It came with an 18mm inner diameter plastic insert. You can order the 19mm insert also which is what I recommend. I used my dremel to bore out the plastic to 19mm. Second thing is that it's easy to have an air leak. I finally figured out that you have to remove the plastic piece from the carb (while prying open the outlet) and push the plastic piece onto the intake pipe first and push it 1mm farther than being flush with the pipe end. That way the pipe will touch the smaller o-ring in the carb outlet, and the plastic will touch the larger o-ring in the carb outlet. Once I did that it worked fine. The part you need to push the fuel line onto comes pointing downward so you need to loosen the screw and rotate the "fuel banjo" to point upwards. Behind that part lies the fuel filter screen. Its not as good as using a separate paper filter in the fuel line. The throttle cable fit into the carb just fine but there was way too much slack in the cable and so I had to unscrew the carb and throttle adjusters out as far as they could safely go. That took out the slack.

It came with a #58 main jet which worked just fine for me although I am at an altitude of 8500 ft. Using the altitude/jetting chart it might be best to also order the #63 jet if you are at sea level, or the #60 jet if you are closer to 4000 ft above sea level. This carb comes with a filter. Don't forget to oil it before use to prevent inhaled dirt from damaging your cylinder.