Hi and welcome to Ninjette!!!
Quote:
Originally Posted by shaverjeff
its extremely boggy down low but seems to run better in the higher rpm range. It fires right up, but takes several minutes before its responsive, and even then down low rpm like below 5k is really rough.
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We’ve all had this issue before. If it’s sat for more than 3-months, you definitely have clogged carbs that needs thorough cleaning to restore to factory fresh condition. Bike ran perfectly when it left showroom floor, and there’s no reason it can’t again with all-factory jetting (even better with downsized main jets).
Behavior down low has nothing to do with main jets. That’s all in choke and pilot circuits. Here’s various areas of adjustments in carbs and which corresponding operating zones they affect.
Low end behavior with warm-up, idle and low-RPM operation is all controlled by choke, pilot-jet and pilot-screw adjustment. And they need cleaning and adjustment, not upsizing. I’d say you need thorough carb cleaning, especially pilot circuit. Spray cleaners no longer work due to removal of chlorinated compounds. You’ll need lots of scrub brushes, guitar wire of various gauges, ultrasonic cleaner with caustic radioactive solvents, micro soda-blaster @
10000psi and lots of previous practice to use them effectively. Search for “clean carbs ducatiman” for cause of this low-end issue and how to fix it.
Here’s dyno-chart of factory 250. You can see AFR in high-end is way, way too rich. Adding more fuel there with larger main jets will do no good. Can even damage engine as extra fuel will wash oil off cylinder walls and cause accelerated wear.
