80 Ironhead with Super E won't idle steady
#1
80 Ironhead with Super E won't idle steady
This is my first bike, when I first got it I took the carb off and tore it completely apart. After a few mistakes and new parts I finally got it back together correctly and put it back on the bike. It fires up every time with the choke on but when I turn that off the idle starts to race. Turning in the idle mix screw brings the idle back down but it doesn't stay there for long. Also, the engine stumbles when I give it throttle, I know it needs some more adjustments but I can't fine tune it until I take it for a quick ride, which I haven't done yet because I'm not sure if the bike will stay running. Any tips would be greatly appreciated.
#2
I've never owned a Super E carb, but it sounds like the classic symptoms of an intake air leak.
One way to test for leaks is to take an UNLIT propane torch and carefully let some of the propane gas flow around the intake manifold while the bike is running. (Not in front of the air cleaner where it will surely get sucked in.) It would probably be a good idea to have a fire extinguisher handy while doing this.
If there's an intake leak, some of the propane will get sucked in and the idle speed will change. Some guys use WD40 or carb cleaner spray to do the test, but those are messy.
One way to test for leaks is to take an UNLIT propane torch and carefully let some of the propane gas flow around the intake manifold while the bike is running. (Not in front of the air cleaner where it will surely get sucked in.) It would probably be a good idea to have a fire extinguisher handy while doing this.
If there's an intake leak, some of the propane will get sucked in and the idle speed will change. Some guys use WD40 or carb cleaner spray to do the test, but those are messy.
#3
+1 on ^
There is a procedure for setting the idle mix [pilot] screw. Once it is set it should never need to be changed. First you have to ensure that there are no intake or exhaust leaks which you can do quite safely with propane gas. So in addition to testing around the intake manifold connections test also at the exhaust pipe connections to the cylinder heads.
Check the setting of the pilot screw - turn it in until gently seated, counting accurately the number of 1/4 turns. Write this number down. You may need to return to this exact setting later.
Then ride the bike to get it up to full operating temperature. This will require riding out of city traffic for a half hour. Idling in the shop etc is not good enough.
1. adjust the idle speed with the idle speed screw to get it about right by feel/hearing/etc.
2. turn the pilot screw in until the engine stumbles, keeping track of the number of 1/4 turns
3. turn the idle screw out until the engine is running well, then continue turning it out until it is running not so well
4. turn it back in the the middle of the two not-running-well settings.
If the idle speed does not change during this procedure then it is possible that the slow jet is too large.
It is also possible that the pilot screw passage needs to be cleaned.
I should mention here that I am not at all experienced with S&S carbs. But the pilot screw system is the same as on Keihin and other carbs.
There is a procedure for setting the idle mix [pilot] screw. Once it is set it should never need to be changed. First you have to ensure that there are no intake or exhaust leaks which you can do quite safely with propane gas. So in addition to testing around the intake manifold connections test also at the exhaust pipe connections to the cylinder heads.
Check the setting of the pilot screw - turn it in until gently seated, counting accurately the number of 1/4 turns. Write this number down. You may need to return to this exact setting later.
Then ride the bike to get it up to full operating temperature. This will require riding out of city traffic for a half hour. Idling in the shop etc is not good enough.
1. adjust the idle speed with the idle speed screw to get it about right by feel/hearing/etc.
2. turn the pilot screw in until the engine stumbles, keeping track of the number of 1/4 turns
3. turn the idle screw out until the engine is running well, then continue turning it out until it is running not so well
4. turn it back in the the middle of the two not-running-well settings.
If the idle speed does not change during this procedure then it is possible that the slow jet is too large.
It is also possible that the pilot screw passage needs to be cleaned.
I should mention here that I am not at all experienced with S&S carbs. But the pilot screw system is the same as on Keihin and other carbs.
#4
Mine is sort of finicky, I have an E. Are you setting it to the factory specs and trying to tweek it from there?
If it's your first bike, how much experience going into carbs have you had?
Did it run good before you took the carb off?
Set the carb to the factory starting specs.
you didn't take anything else apart did you?
Are you 100% sure the carb is right?? Did you take out the jets, blow out the passages, soak it??
Check for intake leak, I like the propane the best.
Mixture screw out 1-1/4 turns
Speed screw 1/2 turn clockwise
Accelerator screw 2 turns CCW
If it's your first bike, how much experience going into carbs have you had?
Did it run good before you took the carb off?
Set the carb to the factory starting specs.
you didn't take anything else apart did you?
Are you 100% sure the carb is right?? Did you take out the jets, blow out the passages, soak it??
Check for intake leak, I like the propane the best.
Mixture screw out 1-1/4 turns
Speed screw 1/2 turn clockwise
Accelerator screw 2 turns CCW
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