Hello all, Just thought Id share my carb settings for reference since this is such a difficult task for some of us to overcome when adding aftermarket parts and getting the bike to run correctly. Your settings will be different depending on many factors (ground elevation, temps outside, etc etc). For me, If I made ANY settings different then the following, the would run like complete trash, ie. Sputtering, bogging down, hanging idles, engine clicking, etc etc.
Also, keep in mind, when I rode, I noticed that the bike would change drastically after about 15 minutes of riding due to heat expansion of metals so when making any changes make sure to do a good long test ride before saying everything runs well.
The Bike:
1975 CB400f with a Big Bore kit to 466, Dyna-tek electronic ignition, Barnett Clutch and springs, Generic air pod filters from 4into1.com, generic aftermarket 4into1.com exhaust and muffler. I run rec fuel/ ethanol free fuel only.
Location:
I live in the Mid-Michigan area, Average elevation in this area is about 600 feet above sea level. I typically ride in temps between 65 and 90 degrees. Humidity varies but doesn't seem to affect how the bike rides.
The Settings:
- Maiin Jets: #78 (Stock is 75), When I tried #80, the bike would sputter due to it being to rich.
- Slow Jets: #38 (Stock is 40) When I left the stock #40 jet, I would get stalling at idle.
- Needle clip setting is on position #1, very top setting to make it more lean.Any other setting for me I would get sputtering and all throttle positions. The bike would run ok with the clip at the second needle position when the bike was cold, after 15 mins of riding I would get sputter.
- Air/Fuel Screw is 1-1/2 turns out
- Carb Floats are at 21mm per manual. This is very important to set right. If I set my floats so much as 1mm different the bike ran like trash, At 21mm the needle inside the float seat will be just slightly depressed to just barely avoid a gas leak from out the tubes. Very important that all float seats are depressed well inside the tubes at the same height and there are no leaks. This can be bench tested before installing on the bike. Its also important to test all of this on a bench with a full gas tank. I tested this with a nearly empty tank got no carb leaks, then filled up the bike, and i got leaks. A full tank will create more pressure and for me it affected how the floats were set to not leak out fuel.
- All valves/tappets clearance set per manual
- All butterfly flap valves sync'd perfectly
- Vacuum sync'd all carbs per manual (very important, this should be done anytime you adjust any carb needle setting, without this done, you will get a hanging idle and bogging down after the bike is warmed up (15 mins +/- of riding, not idling)
If I left anything out, feel free to ask.
