carb tuning
#1
carb tuning
so i just got done rebuilding the engine in my bike (pistons up) I also rebuilt the carb with a carb kit, and accidentally took out the mixture screw also. So im having a hell of a time trying to retune it. I have tried screwing it in all the way then out two turns and tuning from there but it still seems much to rich. I think it might be flooding. my question is even though i didnt touch the float, i put replaced the point on the float with a new one, maybe this one isnt the exact same length as the old one? I also closed the overflow screw all the way should I have it slightly open?
my bike is a 92 sportser 1200
my bike is a 92 sportser 1200
#4
it should be factory cv. sportster use differentneedles than big twins. sounds like a needle. change back too old needle and if you change the emolsion tube and main jet. put the originals back in. thats were i would start.
#5
the carb kit i got was made for the sportster carbs in my generation bike. It looked the same when i replaced it but a difference in clearence cant always be seen by the naked eye, i guess ill have to take the carb off and try to fin the old stuff.
#6
Join Date: Nov 2008
Location: Vancouver Island British Colombia Canada
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You should also have 5 settings on the needle. Drop it 1 or 2 settings & try again.
Also, check your accelerator pump setting. It might be gushing way too much raw fuel when you twist the wick!
Keep us posted.
Hatch.
Also, check your accelerator pump setting. It might be gushing way too much raw fuel when you twist the wick!
Keep us posted.
Hatch.
#7
Hatch could you please explain a little more for me? By settings do you mean 5 complete turns till the screw falls out? Right now it is running best at about one turn out from all the way lean but I'm still getting fuel dripping out the cleaner and rough performance. I did put a new diaphragm in the accelerator pump but I never noticed any ability to have "settings" thanks for all the help so far
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#8
Join Date: Nov 2008
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On a CV carb, there is a big pin that moves up & down in the center. It's around 3 inch long. Accessible from the top, it is fastened with a clip to the carb's moving linkage. If you can see it, you would notice around 5 grooves in the top of the pin. The clip will be locked on one of the 5 grooves.
What you would do is pull the clip, allow the pin to move downwards so you can re attach the clip to a higher groove. This will allow the pin to seat further down than it did before.
the more that pin can move down as you roll off the throttle, the less fuel it will allow through. like stickin' your finger into a leaking hole.
Go to google & type in "exploded view, cv carb"
Look around, you will see all the info in the world on the inside of your carb when you click on the right one.
I think on your carb, you can see the bottom point of this pin if your look down the throat of the carb while you twist the throttle.
For the top adjustment end, you would have to pull a cover off!
Hatch.
What you would do is pull the clip, allow the pin to move downwards so you can re attach the clip to a higher groove. This will allow the pin to seat further down than it did before.
the more that pin can move down as you roll off the throttle, the less fuel it will allow through. like stickin' your finger into a leaking hole.
Go to google & type in "exploded view, cv carb"
Look around, you will see all the info in the world on the inside of your carb when you click on the right one.
I think on your carb, you can see the bottom point of this pin if your look down the throat of the carb while you twist the throttle.
For the top adjustment end, you would have to pull a cover off!
Hatch.
#9
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For your accelerator pump, watch the linkage as you slowly turn it. One of the tabs that the linkage pushes is for your accelerator. It should have a screw in the tab. you can turn the screw to give the accelerator less of a stroke or more depending on your bikes performance & mods. you will see it if you study the linkage long enough!
Hatch.
Hatch.
#10
well when i rebuilt the carb i didnt adjust the jet needle, i can see it looking down the carb throat. I checked the accelorator, i couldnt see any sort of a screw on the fixture aside from the idle screw, there is one connection that has a spring on it, but it just held with a cotter pin.
I too the carb apart again today, adjust the float so the fuel float down a little so it would shut off a little earlier, seemed to run well for about 75 feet then similiar issues of coughing, sputtering, and black smoke, i just cant seem to get this carb tuned for the life of me. I think i have learned that when rebuilding an engine dont mess with the carb untill the engine it broken in then rebuild the carb. I ended up pushing the bike about a mile and half home. I just wish i could get thing to run smoothly, for the short times i have it running well it sounds amazing but it doesnt last long, it still seems to be running rich....
I too the carb apart again today, adjust the float so the fuel float down a little so it would shut off a little earlier, seemed to run well for about 75 feet then similiar issues of coughing, sputtering, and black smoke, i just cant seem to get this carb tuned for the life of me. I think i have learned that when rebuilding an engine dont mess with the carb untill the engine it broken in then rebuild the carb. I ended up pushing the bike about a mile and half home. I just wish i could get thing to run smoothly, for the short times i have it running well it sounds amazing but it doesnt last long, it still seems to be running rich....