ninjette.org - View Single Post - can anyone tell me why this is happening with my idle?

jkv45 · July 27th, 2016, 08:08 AM

You need to start thinking in terms of throttle position when tuning a carb.

Basiclly, idle mixture is controlled by the Pilot Jet with additional fuel being metered by the Idle Mixture Screws.

From there (1/8 ) you transition mostly to the Jet Needle (and Needle Jet - which is not adjustable on the Ninja ) setting through around 1/2 throttle and above where the fuel is eventually controlled almost totally by the Main Jet at WOT (Wide Open Throttle).

If you cruise at 1/2 throttle and it doesn't fuel properly, I would look mostly at the Needle Jet - but the Main Jet also is a factor. It's recommended to set the Main Jet first (WOT running). When you get it to run properly at WOT, focus next on the Needle setting to get smooth running in the 1/2 throttle area. After that, tune the idle mixture screws to get a good idle. If you are 3 turns out or more it indicates the need for a richer Pilot Jet.

Your Idle Mixture passages may be partially blocked if the screws have little or no effect.

I would also confirm that you don't have any vacuum leaks, and look at the plugs.

July 27th, 2016, 08:08 AM	#11
jkv45 Rev Limiter Name: Jay Location: WI Join Date: Jul 2013 Motorcycle(s): '06 SV650n, '00 Derbi GPR, '64 CA77 Dream 305, '70 CL450 Scrambler, numerous dirt bikes Posts: A lot. MOTM - Jun '18, Oct '16	You need to start thinking in terms of throttle position when tuning a carb. Basiclly, idle mixture is controlled by the Pilot Jet with additional fuel being metered by the Idle Mixture Screws. From there (1/8 ) you transition mostly to the Jet Needle (and Needle Jet - which is not adjustable on the Ninja ) setting through around 1/2 throttle and above where the fuel is eventually controlled almost totally by the Main Jet at WOT (Wide Open Throttle). If you cruise at 1/2 throttle and it doesn't fuel properly, I would look mostly at the Needle Jet - but the Main Jet also is a factor. It's recommended to set the Main Jet first (WOT running). When you get it to run properly at WOT, focus next on the Needle setting to get smooth running in the 1/2 throttle area. After that, tune the idle mixture screws to get a good idle. If you are 3 turns out or more it indicates the need for a richer Pilot Jet. Your Idle Mixture passages may be partially blocked if the screws have little or no effect. I would also confirm that you don't have any vacuum leaks, and look at the plugs.