Help!! super b driving me mad
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1st Gear
Joined: Aug 2012
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From: pittsburgh
Help!! super b driving me mad
alright i got a 78 xlh1000 about 2 years ago, and am finaly close to having it on the road i just can not get past this carb.ok hear goes, when i first got the bike i had to clean out the carb( S&S super b ) i got it clean enough to eat out of. replaced the fuel lines. and im not getting enough gas in. i had the old style needle and float with the forked end, and no rubber on the needle. i tryed to get that going no luck i could not open the float up enough and still get it to turn off. i got a new needle, needle seat, and float. but it seams the same not enough fuel coming in. i was told when i bought the bike that it was bored over to 1200. but it supposedly ran before it sat. im sorry if this is al jumbled but im tryin to jot this down quick before i go to work thanks for any help.
Seasoned HDF Member
Joined: Dec 2010
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From: Florida
Well lets trouble shoot. All passage ways must be clear. check your petcock and fuel line to make sure there aren't any kinks and that your petcock supplies enough fuel for the carb. If I'm not mistanken that is a pretty damn big carb for the ironhead. I would probably switch to an e or a cv. Drain your bottom float bolw screw and make sure it is filling up.
Tourer
Joined: May 2010
Posts: 450
Likes: 2
the super b is a great carb for the sportster. That extended intake gets the mixture moving quicker into the cylinders. I have seen back to back dyno runs on the same bike with the b, an su, and a cv. The super b was by far the best of those three, hands down, at almost the entire rpm range it was making more power.
As far as not getting enough fuel, pull the line off of the carb and put it into a bucket or something and turn on the petcock. The fuel should come out of that line much faster then your motor would be able to burn it. If not, check your petcock and filter/ screen in the tank. You only need one or the other, and if you have an inline filter, make sure it is for motorcycles. Big difference in a filter that is deigned for a system using a pump compared to gravity fed.
Had to point out one other thing, whoever told you that the motor was bored to 1200 was a bit misinformed. You cannot bore that motor out to 1200, but you can put a 4 5/8 flywheel in there and that would make it a 1200.
As far as not getting enough fuel, pull the line off of the carb and put it into a bucket or something and turn on the petcock. The fuel should come out of that line much faster then your motor would be able to burn it. If not, check your petcock and filter/ screen in the tank. You only need one or the other, and if you have an inline filter, make sure it is for motorcycles. Big difference in a filter that is deigned for a system using a pump compared to gravity fed.
Had to point out one other thing, whoever told you that the motor was bored to 1200 was a bit misinformed. You cannot bore that motor out to 1200, but you can put a 4 5/8 flywheel in there and that would make it a 1200.
Thread Starter
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1st Gear
Joined: Aug 2012
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From: pittsburgh
Thanks for the responses. Like I said I had to leave for work so I didnt get all the info on that last post. I am getting good flow all the way to the carb. When I cleaned the carb I did the tank and petcock as well. there is a inline filter on it that was put on after i bought the bike, and it has the one on the petcock. So maybe that is where my problem is im gona give that a try. This is my first bike i got it for $1000 off some old guy. It seemed like a good deal, I thought he knew what he was tellin me. but now that you say that jcb1975 i remeber him telling me it was a 3 speed transmission and when i got it running before it was clearly a 4 after that i was never shure what to believe that the guy told me. He told me he rode it too, so youd think he would know. Probaly all a bunch of bs to help get me to buy it.
Tourer
Joined: May 2010
Posts: 450
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If you paid $1000 for a 77 that runs, even if only kind of, you are doing really good. The float on the B is to be set where it shuts off the fuel before it contacts the gasket for the float bowl. Leave a little bit of room so it does not end up sticking open, especially when sitting on the side stand. Do not rely on the petcock for shutting off the fuel, as you need to be able to let the bike run when on the side stand without having it flood itself, even though you should never let the motor idle for more then 2 or 3 minutes at a crack.
Stellar HDF Member
Joined: Aug 2012
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From: Indiana, USA
Pull the bowl and let the float drop, fuel should flow. If it does, shut the petcock, replace the bowl, turn on the pecock turn it back off and gently remove the bowl. Check the fuel level in the bowl, should be about 1/2 - 2/3 full without a float in it. If the needle is not set properly you will quickly run the bowl dry and will have variation as the needle stops and allows fuel to flow. I have replaced the needle and seat and if you have the spring,loaded needle it is very easy to not set it correctly when you cannot trurn the carb upside down. If you have the spring loaded needle and you want to set float height with the carb still mounted....take the spring out of a ball point pin and fasten it to something. Push up on the float until you start to collaps the spring.... note the float seated location.... if necessary bend the float tang and test again. Once you have the float seating level with light spring pressure, replace the bowl and try riding it. You only need 3 things to run...compression, spark, and fuel. If it is running good sometimes you must have compression, if you have cleaned the carb and you are sure the float is set properly you should be getting fuel, if it still isn't running right it may be time to look at spark. Don't know about the 78 sporty but I had an 81 big twin shovel that came with electronic ignition that was always flakey so the trend back then was to replace the electronic ignition with a set of points and condensor.
Tourer
Joined: Jul 2007
Posts: 497
Likes: 8
From: New Egypt, NJ
I had a '74 Ironhead that I stroked to "1200" (74") and ran an S&S Super B with great results.
You may want to take a look "under" the fuel inlet fitting. One time I had an inline filter with a paper (or maybe some sort of fiber) element that came apart. A piece of the filter element got trapped between the fuel inlet fitting (which threaded into the carb body) and the needle valve feed hole. It was too big to pass through the feed hole so it would run for a while, with that piece floating around in there, then suck it into the feed hole and clog it. I had the carb apart (except for removing the fuel inlet fitting) cleaned the thing til I would drink water from the float bowl, put it back together and have the same problem. Did that over & over, drove myself half crazy until I took that fuel inlet off and saw that damned sliver of paper. Maybe you have something stupid like that going on.
Definitely get rid of the inline filter if the petcock has a screen, and it wouldn't hurt to pull the petcock out & inspect the screen.
Those B carbs are reliable, and very simple. have one I plan to run on a Pan project if I ever get it togethrr.
You may want to take a look "under" the fuel inlet fitting. One time I had an inline filter with a paper (or maybe some sort of fiber) element that came apart. A piece of the filter element got trapped between the fuel inlet fitting (which threaded into the carb body) and the needle valve feed hole. It was too big to pass through the feed hole so it would run for a while, with that piece floating around in there, then suck it into the feed hole and clog it. I had the carb apart (except for removing the fuel inlet fitting) cleaned the thing til I would drink water from the float bowl, put it back together and have the same problem. Did that over & over, drove myself half crazy until I took that fuel inlet off and saw that damned sliver of paper. Maybe you have something stupid like that going on.
Definitely get rid of the inline filter if the petcock has a screen, and it wouldn't hurt to pull the petcock out & inspect the screen.
Those B carbs are reliable, and very simple. have one I plan to run on a Pan project if I ever get it togethrr.
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