Carburator question

wrench · Feb 9, 2014

there is no set number of turns for the air/fuel mixture screw. 2 turns is just a starting point so it should start. with the engine warmed up turn the mixture screw in or out till it is at its highest idle point. turn it in and if it idles up keep turning till it starts to slow. then back it up to the highest point of idle. if it starts to die down when you turn it in, then turn it out till the motor idles up to the highest point before it starts to die down. you peak it. that's what the guy was doing when he adjusted it by listening to the motor. each and every engine is different and the air/mix screw should be dialed in for each motor. if you have a backfire when you back off the throttle then turn the air/mix screw 1/4 to 1/2 turn out to cure it. as stated above an exhaust leak will also cause a backfire when backing off the throttle. a slightly rich air/fuel mixture screw adjustment WILL NOT wash the cylinder walls. you have to be very over rich on the jets and flush pump to do that.

bigdogtech01 · Feb 9, 2014

The S&S carb is a good carburetor, easy to adjust, easy to diagnose problems, very user friendly... but certainly not the best for the street. One a drag bike, yes. But street would be a Mikuni and next to that, EFI.
As far as the Flush pump (you mean Accelerator Pump) goes, it should not be overlooked. With the amount of Ethanol in the fuel now a days, it's a very common problem for the accelerator pump nozzle to plug up and not fan out like it should, along the with rubber pump diaphragm not functioning correctly as well. The base setting for the accelerator pump screw is 2 1/2 turns out from bottom.
With the mixture screw. Base setting is 1 1/2 turns out from bottom. If you are at 2 turns or more out, you have another problem with carburetor. Finale adjustment will usually end up around 1 1/2-1 3/4 turns out. If more than that, you likely have an intake leak. If you have it adjusted in less than 1 1/2 and bike is still running smooth, most likely the fuel screw is worn out (see pictures above by Franco)
With motor at operating temp and at idle, the correct way to adjust the fuel screw is to close off the accelerator pump screw all the way. Doing this the idle will drop, but motor should not stall. If needed, you can adjust the idle up just a little so it does not stall while making adjustments (keep idle around 1000 rpm) With accelerator pump screw closed off, you now adjust the fuel screw from your base setting of 1 1/2 turns. Adjust slowly in watching the amount you turn needle, till the motor RPM start to slow down. Now turn back out, watching the amount of turn till the RPM start to slow down. Go half way between these two points and leave there for now.
Now go back up and turn the accelerator screw back out 2 1/2 turns and adjust your idle back to around 1000 rpm.
At this point you will have to take the bike out and test ride to see how it responds to throttle under load. If it hesitates, you will need to adjust the accelerator pump screw either clockwise or counterclockwise. But, you will only be adjusting this 1/8 turn at a time. Adjust and test ride and if it gets better, then keep going that direction until it's 100%, if it gets worse, adjust the other direction until it's 100%
If you are getting a lot of deceleration popping, and you know exhaust gaskets are new and not leaking and everything else is good, turn the fuel screw out a little at a time ( 1/16 ) until the popping is better. 1/4 to a 1/2 turn is too much. These needles are fine adjustments. And keep in mind, some exhaust systems, no matter what carburetor or even fuel injection, they will still have some deceleration popping.

pauldeepsea · Mar 16, 2014

I am working on getting my E carb setup adjusted and just will not work. I have done the factory reset and adjusted etc.... the plugs are not burning even. the rear plug is only burning on 1 side and is lean the front plug is burning dark.. I am thinking of putting it on the dyne. I know the adjustment is pretty easy and jetting is not that difficult but I am curious to see what is going on with the bike... IT seems to be running hot too. this may be a case of me over diagnosing the issue but the bike is coughing and sputtering and I keep adjusting the carb to make it right..

bigdogtech01 · Mar 16, 2014

pauldeepsea said:
I am working on getting my E carb setup adjusted and just will not work. I have done the factory reset and adjusted etc.... the plugs are not burning even. the rear plug is only burning on 1 side and is lean the front plug is burning dark.. I am thinking of putting it on the dyne. I know the adjustment is pretty easy and jetting is not that difficult but I am curious to see what is going on with the bike... IT seems to be running hot too. this may be a case of me over diagnosing the issue but the bike is coughing and sputtering and I keep adjusting the carb to make it right..

Sounds like an intake leak to me...most likely the seals between the manifold and head are bad. At least one of them. Very common problem and only last a couple years.

pauldeepsea · Mar 16, 2014

I knew I should have replaced them when I had it apart to change the idle cable. I even have new seals but decided not to mess with it.

pauldeepsea · Mar 16, 2014

bigdogtech01 said:
Sounds like an intake leak to me...most likely the seals between the manifold and head are bad. At least one of them. Very common problem and only last a couple years.

I am going to start it and spray the intake manifold with carb cleaner to see if it changes the idle before I start taking it apart again..

pauldeepsea · Mar 21, 2014

Carb adjustments

initial problem was carb was coughing/sneezing a low idle usually between 1st and 2nd gear. (S&S Super E)

Plugs were burning very rich

some of the steps I have done to correct the issues.
Verified carb vent screw was removed :2thumbs:
Reset Carb to factory starting point and adjusted as per the S&S tech manual
changed intermediate jet from a .0295 2 sizes bigger
replaced spiked air filter with a new air filter from wimmer machine.
Replace exhaust gaskets
checked manifold gaskets and verified no leaks at manifold and at the exhaust manifold.
Started up and let it warm up to make final corrections and it still seems to be coughing a bit. I did not have time to ride it tonight to take it for a test ride but tomorrow and I am going to buy new plugs to document the mixture. it is still coughing and when I rev the engine while in neutral I am getting blue flames from the exhaust not sure if this is due to the short pipes *FSD Sinful

Anyone see any obvious oversight on the adjustments? I will post my findings after the test ride and more adjusting.

bigdogtech01 · Mar 21, 2014

pauldeepsea said:
initial problem was carb was coughing/sneezing a low idle usually between 1st and 2nd gear. (S&S Super E)

Plugs were burning very rich

some of the steps I have done to correct the issues.
Verified carb vent screw was removed :2thumbs:
Reset Carb to factory starting point and adjusted as per the S&S tech manual
changed intermediate jet from a .0295 2 sizes bigger
replaced spiked air filter with a new air filter from wimmer machine.
Replace exhaust gaskets
checked manifold gaskets and verified no leaks at manifold and at the exhaust manifold.
Started up and let it warm up to make final corrections and it still seems to be coughing a bit. I did not have time to ride it tonight to take it for a test ride but tomorrow and I am going to buy new plugs to document the mixture. it is still coughing and when I rev the engine while in neutral I am getting blue flames from the exhaust not sure if this is due to the short pipes *FSD Sinful

Anyone see any obvious oversight on the adjustments? I will post my findings after the test ride and more adjusting.

If you say the plugs looked to be black from running rich, why would you go up 2 sizes on jet?

.031 should be big enough for a stock motor.
Blue flames is an indication of a lean condition (intake seal or rubber plug on top of carb) bad exhaust leak, or even something going bad in the ignition system. I would change the Spark plugs out first off. See if it's still doing the same thing. You might be chasing something you think is fuel, when it's really electrical. The stock ignition systems are known to fail (long before the EHC) so I would keep this in mind along with the fuel/air side of things.

pauldeepsea · Mar 22, 2014

I think I found the issue I was close to saying fuck it and take it to a shop but decided to really give it a final shot.
My rear manifold was leaking and my forward exhaust also had a slight leak. Brake fluid changed the idle so I will start by taking the manifold off and replacing the gaskets.
additionally, this is on the sled not the BDM so no EHC and the ignition system is a ultima.

Andrew thank you very much for responding! I will post more as I dig through the issue hopefully this is the root cause of the carb coughing etc...

Thanks again!
Paul

bigdogtech01 · Mar 22, 2014

pauldeepsea said:
I think I found the issue I was close to saying fuck it and take it to a shop but decided to really give it a final shot.
My rear manifold was leaking and my forward exhaust also had a slight leak. Brake fluid changed the idle so I will start by taking the manifold off and replacing the gaskets.
additionally, this is on the sled not the BDM so no EHC and the ignition system is a ultima.

Andrew thank you very much for responding! I will post more as I dig through the issue hopefully this is the root cause of the carb coughing etc...

Thanks again!
Paul

Glad you found the problem. That's all I ever use is a can of brake/parts cleaner to find the intake leak. Just make sure you replace BOTH seals

It's a pretty common area to leak, so expect to see it again in the future.

Kdub · Mar 22, 2014

Peckerwood said:
Don't know that S&S carbs are "shit", but mine seems to require periodic maintenance. Francoblay's attachments are simple to perform and will hook you up IF your jetting is correct. It's a simple process you can do yourself. If you feel the need to spend the $$$ to change out, a lot of my H-D riding friends have switched to Mikuni.
You also might want to have a look on top of your carb, there's a little rubber boot that tends to crack and dry rot, causing a lean condition. Replace if necessary.

Where could a guy find a replacement for this little rubber boot? Upon inspection mine is rotted as well. I'm running a little lean and figured I would go through my carb this spring.

bigdogtech01 · Mar 23, 2014

Kdub said:
Where could a guy find a replacement for this little rubber boot? Upon inspection mine is rotted as well. I'm running a little lean and figured I would go through my carb this spring.

Any automotive shop will have them...usually in the isle with the hoses and pipe fittings.

BadDawg Bill · Aug 23, 2014

Maverick said:
After a year and a half of fighting this problem I removed the spike air cleaner and reinstalled the stock one. Now all the problems are gone. No lag in acceleration and the dog is running great. Guess that was the problem all along.

The problem was when you put on the spike you changed the velocity of air going into your carb. You needed to rejet and reset the carb. If you just put your org unit back on and it runs fine then that was the problem.

One time it took me 6 hrs to get my carb right after puttin on a Ravera long intake.

francoblay1 · Aug 23, 2014

Here are lots of us running the Spike with no problems at all...

... maybe you did not do all it needs to be done when installing an after-market air-cleaner, like taking the "Bowl Vent Plug", etc...

:cheers:

Sven · Aug 23, 2014

bigdogtech01 said:
The most common problems I have found are...
-Intake manifold seal leak.

Here was the very first one on the list and that was a day later if no sooner.

Signed 3 pages 20 some odd days later,

NOLTTech01

:roll: :hi:

:2thumbs:

BadDawg Bill · Aug 23, 2014

S&S Carb Tuning Tips

Idle Circuit
1. Start engine and run until slightly warm (about 1 to 2 minutes).
2. Turn RPM adjusting screw to obtain an idle speed of approx. 1000 RPM.
3. Turn Idle mixture screw clockwise, slowly leaning mixture until engine starts to die. Next, turn screw counterclockwise, slowly richening mixture, until engine RPM start to fall off, counting the number of turns as you do so. Mixture adjustment is correct when screw is positioned about halfway between these points which should be approx. 1/4 to ½ turn out from lean side of adjustment range.
Note:
Turning screw out (counterclockwise) makes idle mixture richer. Turning screw in (clockwise) makes mixture leaner. Normally correctly adjusted screw will be between 1 1/4 – 1 ½ turns out from bottom if intermediate jet size is correct.

4. After initial idle mixture adjustment is set, reset engine idle to approximately 1000 RPM. A lower idle speed can cause hard starting; poor throttle response erratic idle and unnecessary engine wear.
5. Once the engine has reached normal operating temperature, repeat steps 3 & 4.

Idle Circuit Notes:
•If idle adjustments are made before engine is fully warmed, idle mixture will be rich when engine reaches operating temperature.
•Whenever intermediate jet change is made, idle mixture screw must be readjusted.
•If idle mixture screw is more than 1 3/4 out after idle mixture is correctly adjusted, it is a fairly good indication that the intermediate jet may be too small and should be changed to the next larger size. Conversely, if the idle mixture screw is less than 1 1/4 turns out the intermediate jet may need to be changed to the next smaller size.
•If idle mixture screw is turned completely in engine should not run at idle. If engine continues to run at idle with idle mixture screw seated, recheck initial setting of idle speed screw, and make sure enrichment plunger is seated. If engine still runs at idle with idle mixture screw all the in, contact S&S Tech support.

Accelerator Pump:
The function of the accelerator pump is to improve throttle response when rapidly opening the throttle at low rpm and to aid in cold starts. S&S sets the accelerator pump adjusting screw for maximum volume (all the way out) to aid during initial start-up after installation. Turning the screw inward (clockwise) decreases delivered pump volume. Turning it outward (counter clockwise) increases pump volume.

Adjusting the Accelerator Pump:
1. Warm engine to operating temperature.
2. Turn pump travel adjusting screw inward until screw contacts pump actuator arm. This shuts off the pump. Caution – closing adjusting screw with excessive force can cause irreversible damage to screw threads in carb body.
3. With engine warm and at idle, blip throttle and note throttle response.
4. Turn pump travel screw outward or counter clockwise about 1/4 turn at a time and recheck throttle response until engine no longer hesitates. This is usually about two turns out.
5. Minimum pump travel is recommended to conserve fuel, prevent spark plug fouling, and curtail black smoke from pipes when blipping throttle. Black smoke is usually an indication of a rich condition or excessive accelerator pump travel.

Some Performance Notes:

•To be sure idle mixture adjustment is correct; always check with fully hot engine.
•If popping or backfiring through air cleaner occurs upon taking off, this indicates a lean condition requiring that a larger intermediate jet be installed (one size larger) (size is stamped on bottom of jet).
•When fine tuning the intermediate circuit, it is best to turn off the accelerator pump completely. It can mask jetting symptoms.
•Whenever the intermediate jet is changed, the idle mixture should be readjusted.
•If engine backfires or sputters in carburetor or breaks up and or dies during acceleration, increase or richen main jet size.
•If engine runs flat and sluggish or blubbers, or will not take throttle, decrease main jet size.
•Always use an insulator block between carb and manifold. If not the heat transfer from the manifold to the carb may cause a temporary rich condition at idle and low speed rpm.

francoblay1 · Aug 23, 2014

Yup! here some more attached. :up:

Carburator question

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