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A few weeks ago I posted my diagnosis of a rich-condition and resulting black-colored and fouled #4 spark plug in my 1980 GS1000G (with CV carbs),
I believe that I solved that problem by discovering and replacing a bent float pin in #4 carb. That same day, I also replaced the float valve and seat assemblies on all four carbs, checked compression (150 +/- all four cylinders), checked ignition (good spark to all four plugs), and checked to make sure that the chokes were actually fully closed when the choke knob/cable was pushed in to the closed position. Also, a month ago, I cut back the coil wires about ?-inch to expose nice fresh copper wire and replaced all my plug caps with brand-new NGK caps (the correct impedance, 3 Ohms, if my memory serves me correctly). I synchronized the carbs with a Morgan Carb Tune, checked/adjusted valve shims, and checked the coils using an electric multi-meter following diagnostic directions posted by Earl Fornes and others on this website.
In the past few weeks I have been trying to achieve the elusive desirable light gray to light tan color on all four spark plugs, by carefully adjusting the fuel mixture screws. (I am aware that I should check carb synch again, but that involves a friend?s time and synch tool, and I haven?t gotten around to that yet).
The good news is that indeed, at the beginning of the fuel mixture fine-tuning process, I was able to achieve lighter spark plug insulator color (on all four cylinders) by turning the fuel mixture screws in (clockwise, looking down from above the carbs). I also noticed that the unburned/partly burned exhaust smell had gone away. All this made me feel good, thinking that I was actually accomplishing something and was acquiring more motorcycle mechanical skills, never mind that I could actually spend more time riding the motorcycle than fixing it!
The bad news is that, over the past few weeks, I have had to adjust the screws leaner and leaner, yet all the plugs are slowly getting darker and darker. I have swapped plugs around, checked spark again, etc., etc. Right now, I have the fuel screws on #1 and #3 lightly seated all the way in, and the other two are around just one turn out from seated. From other peoples? posts on the GSR, I believe that ?normal? settings for these fuel mixture screws should be generally in the range of 1 ? to 2 ? turns out. So definitely, something?s wrong.
Also, although the bike starts nice cold or hot (needs hardly any choke this time of year) and idles and runs nice, no misses or bogging, etc., there seems to be an increase in noise between 3000 rpm and 4000 rpm, particularly in 2nd and 3rd gear under light to moderate throttle settings. The noise is sort of a ?rattling? sound that I first thought was a loose component in my windshield or gauges or somewhere else. However, I screwed around with the shield and gauges and horn and tank mountings, etc. and I think I?ve ruled that stuff out. I?m now thinking it?s valve train noise.
Another symptom is that I?m only getting 30 mpg with this bike, whereas I get 40 mpg riding the same way (speed, throttle, etc.) with my 1979 GS1000L that has VM carbs, K&N pods, Dynojet kit, and 4 into 1 pipe. Same rider, same commuting route to work, same 1000cc displacement; but 10 mpg difference in fuel economy!
Last night, just as I was running out of motorcycle-fixing time before dinner and the end of my wife?s patience with me and motorcycles, I removed #1 mixture screw, and discovered that there is no rubber O-ring in the #1 fuel mixture screw assembly; just the screw, spring, and metal washer. At this time, I can only assume that there are no O-rings in the other carb fuel mixture assemblies.
My questions are:
Should a 1980 GS1000G have O-rings in the fuel mixture screw assemblies?
If so, how would the absence of the O-rings affect my fuel mixture and resultant plug reads?
Could it be that my bike originally had fuel mixture screw O-rings and that they have deteriorated into little particles and plugged something up inside the carbs (even though I?ve had the ####ing carbs off the bike and cleaned them three time in the last three months)?
Any other ideas
I believe that I solved that problem by discovering and replacing a bent float pin in #4 carb. That same day, I also replaced the float valve and seat assemblies on all four carbs, checked compression (150 +/- all four cylinders), checked ignition (good spark to all four plugs), and checked to make sure that the chokes were actually fully closed when the choke knob/cable was pushed in to the closed position. Also, a month ago, I cut back the coil wires about ?-inch to expose nice fresh copper wire and replaced all my plug caps with brand-new NGK caps (the correct impedance, 3 Ohms, if my memory serves me correctly). I synchronized the carbs with a Morgan Carb Tune, checked/adjusted valve shims, and checked the coils using an electric multi-meter following diagnostic directions posted by Earl Fornes and others on this website.
In the past few weeks I have been trying to achieve the elusive desirable light gray to light tan color on all four spark plugs, by carefully adjusting the fuel mixture screws. (I am aware that I should check carb synch again, but that involves a friend?s time and synch tool, and I haven?t gotten around to that yet).
The good news is that indeed, at the beginning of the fuel mixture fine-tuning process, I was able to achieve lighter spark plug insulator color (on all four cylinders) by turning the fuel mixture screws in (clockwise, looking down from above the carbs). I also noticed that the unburned/partly burned exhaust smell had gone away. All this made me feel good, thinking that I was actually accomplishing something and was acquiring more motorcycle mechanical skills, never mind that I could actually spend more time riding the motorcycle than fixing it!
The bad news is that, over the past few weeks, I have had to adjust the screws leaner and leaner, yet all the plugs are slowly getting darker and darker. I have swapped plugs around, checked spark again, etc., etc. Right now, I have the fuel screws on #1 and #3 lightly seated all the way in, and the other two are around just one turn out from seated. From other peoples? posts on the GSR, I believe that ?normal? settings for these fuel mixture screws should be generally in the range of 1 ? to 2 ? turns out. So definitely, something?s wrong.
Also, although the bike starts nice cold or hot (needs hardly any choke this time of year) and idles and runs nice, no misses or bogging, etc., there seems to be an increase in noise between 3000 rpm and 4000 rpm, particularly in 2nd and 3rd gear under light to moderate throttle settings. The noise is sort of a ?rattling? sound that I first thought was a loose component in my windshield or gauges or somewhere else. However, I screwed around with the shield and gauges and horn and tank mountings, etc. and I think I?ve ruled that stuff out. I?m now thinking it?s valve train noise.
Another symptom is that I?m only getting 30 mpg with this bike, whereas I get 40 mpg riding the same way (speed, throttle, etc.) with my 1979 GS1000L that has VM carbs, K&N pods, Dynojet kit, and 4 into 1 pipe. Same rider, same commuting route to work, same 1000cc displacement; but 10 mpg difference in fuel economy!
Last night, just as I was running out of motorcycle-fixing time before dinner and the end of my wife?s patience with me and motorcycles, I removed #1 mixture screw, and discovered that there is no rubber O-ring in the #1 fuel mixture screw assembly; just the screw, spring, and metal washer. At this time, I can only assume that there are no O-rings in the other carb fuel mixture assemblies.
My questions are:
Should a 1980 GS1000G have O-rings in the fuel mixture screw assemblies?
If so, how would the absence of the O-rings affect my fuel mixture and resultant plug reads?
Could it be that my bike originally had fuel mixture screw O-rings and that they have deteriorated into little particles and plugged something up inside the carbs (even though I?ve had the ####ing carbs off the bike and cleaned them three time in the last three months)?
Any other ideas
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