I bought a Colortune over the winter and since the weather was condusive to riding today I got Rita out (1981 GS850G) and pulled the tank and started "playing with my new toy. I really should have done a little research first I now realize. Not really having any idea what I was doing I started adjusting the only screws I could see (I think they are air screws, on top, engine side of the carbs). Nothing I did seemed to make any difference in the combustion color; it stayed a pretty steady blue with an occasional yellow flash. To make a long story short, I wasn't really paying close attention to what I was doing and lost track of how far I had turned each so I don't think I got them set back to where they were; I had to turn my idle up to about 1500 to keep her running. Took it for a ride and acceleration seems to be quicker than before but vibration seems a little higher; possibly my imagination but there seemed to be more valve train noise when I got home and took my helmet off. I drove about 30 miles. I guess my question is this: are there standard settings for these screws that I should attempt to set them to or some method I can use to make sure I have them right? I am really a novice where carbs are concerned and probably should have asked before fiddling but you know how it is when the sun comes out and you have a new tool to try out... any knowledge out there I can tap in to?
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Carb knowledge?
I have to preface this by saying I am not normally a moron....
I bought a Colortune over the winter and since the weather was condusive to riding today I got Rita out (1981 GS850G) and pulled the tank and started "playing with my new toy. I really should have done a little research first I now realize. Not really having any idea what I was doing I started adjusting the only screws I could see (I think they are air screws, on top, engine side of the carbs). Nothing I did seemed to make any difference in the combustion color; it stayed a pretty steady blue with an occasional yellow flash. To make a long story short, I wasn't really paying close attention to what I was doing and lost track of how far I had turned each so I don't think I got them set back to where they were; I had to turn my idle up to about 1500 to keep her running. Took it for a ride and acceleration seems to be quicker than before but vibration seems a little higher; possibly my imagination but there seemed to be more valve train noise when I got home and took my helmet off. I drove about 30 miles. I guess my question is this: are there standard settings for these screws that I should attempt to set them to or some method I can use to make sure I have them right? I am really a novice where carbs are concerned and probably should have asked before fiddling but you know how it is when the sun comes out and you have a new tool to try out... any knowledge out there I can tap in to?Tags: None
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lurch12_2000
You should reference a manual but if you are talking about the pilot mixture screws then usually they are 1 1/2 to 2 full turns out. I would try carb #1 and carefully turn clockwise(in) and count the turns til it doesn't turn anymore(Don't force it!!). I use only two fingers to be sure I'm not muscling it too much. See if it is about 2 turns to close it and now turn it out 1 1/2 turns. Do this for each carb and write down how many turns they were originally out to get a starting point to go back to if you mess things up. But you will wind up with all at 1 1/2 turns out for the first test. You might have to then add a 1/2 turn (2 total) to all to see if it runs better.
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BassCliff
Hi,
From my little BikeCliff website, here is one suggested procedure for setting the pilot screws:
The Highest RPM Method (by Mr. psyguy)- Take off the tank.
- Set the pilot screws at 2 turns out.
- Warm up the engine and let it run.
- Adjust the idle to approx. 900 rpm.
- SLOWLY turn the screw at carb #1 in - at some point the rpms are going to start dropping and the engine wont run as smoothly.
- Start turning the screw back out while you get the highest rpm read and a smoother sound from the engine.
- At some point, turning the screw out further won't make any difference (and even further out may again take away the smoothness and the rpms).
- You want your screw turned IN as much as possible without affecting the rpms/smoothness.
- Re-adjust the idle to 900 rpm.
- Stop the engine to let it cool down a bit or place a big fan in front of the engine and do this while the outside air is cooler (morning/winter).
- Proceed with carb #2.
- Repeat steps 4 through 10 as necessary for all carburetors.
- When complete, re-adjust the idle knob for the correct rpm as per your factory manual (usually 1050 rpm +/-100 rpm). In any case, do not idle below 900 rpm as this may result in insufficient oil flow.
Thank you for your indulgence,
BassCliff
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gaillarry
I found the carbtune to be more of a problem than a solution. I used it on my 85 GS550 and spent a lot of time adjusting the air screws with no great improvement.
I've since used the spark plug chop to provide better results.
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Forum SageCharter Member
Past Site Supporter- May 2002
- 3869
- The Gulf Coast of south Florida in the winter and northern Nevada in the summer
Me, too!
Originally posted by gaillarry View PostI found the carbtune to be more of a problem than a solution. I used it on my 85 GS550 and spent a lot of time adjusting the air screws with no great improvement.
I've since used the spark plug chop to provide better results.1980 GS1100E....Number 15!
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Originally posted by gaillarry View PostI found the carbtune to be more of a problem than a solution. I used it on my 85 GS550 and spent a lot of time adjusting the air screws with no great improvement.
I've since used the spark plug chop to provide better results.
however, the old elect system would be contributing A LOT to the "bad" colortune readings, i should imagineGS850GT
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BassCliff
Almost famous
Originally posted by psyguy View Postwow, i'm getting quoted now
Thanks for letting me quote you on my little BikeCliff website.
Thank you for your indulgence,
BassCliff
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If you turn the screws all the way in it doesn't turn the flame yellow? If not your o-rings are ate up and you need to get new ones.
The colortune set my pilot mixture too lean and I had to come out another turn or so. It's great for a ballpark setting but you can do this with the highest rpm method which I use.1983 GS 1100E w/ 1230 kit, .340 lift Web Cams, Ape heavy duty valve springs, 83 1100 head with 1.5mm oversized SS intake valves, 1150 crank, Vance and Hines 1150 SuperHub, Star Racing high volume oil pump gears, 36mm carebs Dynojet stage 3 jet kit, Posplayr's SSPB, Progressive rear shocks and fork springs, Dyna 2000, Dynatek green coils and Vance & Hines 4-1 exhaust.
1985 GS1150ES stock with 85 Red E bodywork.
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