I am installing the Dynojet kit along with the Diamond G Snorkle, Twin Air filter, I.D.S.-X Supertrapp Pipe, and Diamond G CDI Black Box. My question is this: IF the stock jets are 138F/142R as indicated in the service manual, why do the Dynojet instructions call for the smaller 132F/136R for my situation, aftermarket filter and pipe, altitude 750 to 3300ft. Is the stock jetting much too rich to begin with and if so why? My plugs are usually black and sooty on inspection. It runs fine cold or hot, but will backfire sometimes when snapping off the throttle from high engine speed.(In stock form). Also, what happens when you use the 5th notch as instructed for altitudes under 5000 ft. instead of the 4th.? I though these companies test this stuff so we don't have to use so much trial and error, since it is a pain to get to the carbs. Isn't that why we have to pay so much for a few small parts? How many of you have had to rejet the carbs after following the instructions, and how many times? I know there are some people out there with my exact set-up, and by the way, I don't have the CDI box yet but thought some wishful thinking might help speed it's process! Perhaps it would help other 650'ers to create a list of each persons final results, i.e. a brief post describing what mods are installed, what jet, needle clip position, air screw settings, and so on and the results, to include previous tries and the effect of the wrong settings. I would like to only rejet once, and without having to call a psychic hotline to get the correct settings!

 

As expained to me by other carb guru's is that the factory jets are measured different than after market jets. I think the factory measured by cfm and after market are measured by the hole size I think don't remember exactly GAFF is the guy to ask on that.