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Hi, Anonymous you need to make sure you have no intake leaks by spraying some Brake Kleen, Contact Cleaner, Starting Fluid etc. around the intake manifold and seals, if the RPM's go up or down significantly then you have a leak that needs to be fixed before you can continue with the carburetor adjustment.
The engine should be at operating temperature with the choke off to set the idle between 950-1050 rpm. Turn the idle skrew clockwise to increase the idle speed and counterclockwise to decrease the idle speed. If you have access to your air-fuel mixture skrew you may turn it as well, if not there is a video below on how to gain access, make sure you start with clean or new spark plugs. Gently turn the air-fuel mixture skrew clockwise until it starts to bottom out "STOP" do not over tighten as it will damage the taper on the end, now back the skrew out 1-1/2 full turns to establish a starting point start the engine and check the idle rpm's and turn the idle skrew accordingly for 950-1050 rpm if necessary, turn the air-fuel mixture skrew 1/4 turn at a time and let the engine settle for about 10 seconds, turn the skrew clockwise for a leaner mixture and counterclockwise for a richer mixture, you are seeking the highest rpm your air-fuel mixture skrew can acquire without going past 3 full turns from bottom then resetting the idle skrew back down to 950-1050 rpm If you can not detect any rpm change and can not stall the engine by turning the air-fuel mixture skrew all the way in then your pilot/low-speed jet is too big and needs to be replaced with the next size smaller. Final adjustment should be made with a clean air filter mounted to the carburetor.
For more information about your issue and valuable "FREE" downloads that you will need for viewing or printing please click on the blue links below. Good luck and have a wonderful day. 1979 Honda CBX Cold Start and Idle Lazy Slow Return to Idle or Erratically High Idle Honda 1979 CBX Shop Manual http://www.partsfish.com/page/oem-parts-for-honda 1979 Honda CBX Owner Manual
Hi, Susanmhogg and the usual suspects are:
1. Fouled spark plugs.
2. Severely discharged or a damaged battery should have 12.5 volts or more and be able to pass a proper "LOAD" test if necessary, you may have a preliminary reading of 12.5 volts or more but little or zero amperage the battery is faulty and must be replaced, AGM batteries fail in this scenario more so than lead-acid batteries.
3. Check battery terminals for damage or corrosion, check the battery cables at "BOTH" ends for loose, corroded, or broken connectors, "INSIDE" and outside the cable harness, perform connector wiggle test and check cables with an ohmmeter if necessary.
4. Loose connection at ignition coil or plug between ignition sensor and module.
5. Spark plug cables in bad condition, shorting/leaking, spark plug cable connections loose check for spark leakage in the dark.
6. Faulty ignition coil or electronic control module.
7. Faulty pulse coil.
8. Faulty CKP, CMP, or BAS sensor.
9. Faulty ignition switch.
10. Faulty run/off switch
11. Tilt sensor needs a reset.
12. Security alarm failing to disarm needs reset
For more information about your issue and valuable "FREE" downloads that you will need for viewing or printing please click on the blue links below. Good luck and have a wonderful day. The International CBX Owners Association How to diagnose no spark situation on motorcycle https://www.partsfish.com/page/oem-parts-for-honda Honda CBX 6 Cylinder 1047cc Workshop Manual 1979 NEW eBay $36 Honda CBX 1000 Owners Handbook eBay $27
Hi, Nielyerdon if you have changed your engine size, fuel delivery system, air filter size or flow rate, mufflers or exhaust system or a significant change in altitude your carburetors need re-tuning and if your fuel system (gas tank, filters, fuel valve and carburetor) is contaminated with ethanol sludge, varnish, rust, dirt, water etc. or your bike has been sitting for months or years without running these components must be "PROPERLY" cleaned and reassembled "CORRECTLY" before any adjustments can be made. Tuning your carburetor is fairly simple once you understand the basic principals. You engine is a simple airbox sucking air in and blowing it out, it is finely tuned at the factory for maximum performance once you upset that delicate balance by changing air filters, camshafts or exhaust systems your performance may go down the and the engine may run poorly, you need to compensate the air-fuel mixture in the carburetor in order for the engine to run smoothly and at peak performance. If you are running multi carburetors you need to sync them first and make sure your air cleaner element is clean and dry for paper elements or lightly oiled for foam and meshed elements and properly installed. Here is how and where you compensate trouble: "TIP" if your engine "BOGS" you're not getting enough fuel.
1. Close to 1/8 throttle is managed by the air screw and pilot/slow jet.
2. 1/8 to 1/4 throttle is managed by the air-screw, pilot/slow jet, and throttle slide.
3. 1/4 to 1/2 throttle is managed by the throttle slide and jet needle.
4. 1/2 to 3/4 throttle is managed by the jet needle, needle jet, main jet, and air jet.
5. 3/4 to wide open throttle is managed by the main jet and air jet.
6. A wide open throttle is managed by the main jet.
If you are running lean, spark plug electrode color is white, engine runs hot and feels like it is starving for fuel you need to go up on the jet size or move the c-clip down one notch. If you are running rich, spark plug color is black or dark gray, the engine runs cool, and bogs down when accelerating you need to go down on jet size or move the c-clip up one notch. When your carburetor is properly tuned for maximum performance your spark plug electrode will be a light tan color like coffee with cream. If you prefer fuel economy over performance you can go down on main jet sizes until a satisfactory level of lower performance is acceptable versus MPH, your spark plug color will be whiter and your engine will run warmer. These tuning adjustments will only make improvements if your intake and exhaust system have no air leaks or sealing issues and the entire electrical system is in proper working order and you have no mechanical issues.
For more information about your issue and valuable "FREE" downloads that you will need for viewing or printing please click on the blue links below. Good luck and have a wonderful day. The International CBX Owners Association HONDA CBX CBX1000 CARBURETOR PERFORMANCE TUNING JET KIT 24 MAIN JETS eBay How to sync carbs on motorcycle Carb Sync Tool eBay Honda 1979 CBX Shop Manual https://www.partsfish.com/page/oem-parts-for-honda 1979 Honda CBX Owner Manual