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  1. #1

    Default Shovelhead w/ Super E Hanging Idle After Rev

    Hi all, I've spent some time trying to diagnose this problem and I'm looking for some second opinions. Bike is a freshly rebuilt 1973 Shovelhead chopper with Super E carb, kick only, belt drive, ratchet top, fresh plugs, new coil. I have the carb set per the starting specs on the S&S youtube setup video. I have had it running several times since the rebuild working through heat cycles and a few short rides, now I am trying to dial it in. I pulled the plugs after a ride the other day and noticed the plugs were pretty much white, and that the bike is harder to start, so I think my issue is mixture related but I'm not sure what is going wrong. The acc. pump squirts as it should with throttle and you can see gas in the carb body when it's running and when you kick it over.

    What happens is when the bike is running and you give it even just a little throttle (maybe like 3000 rpm ish) and then let off, the idle hangs in that rpm range and takes a while to come back down. It is not affected by pulling in the clutch. I know this problem is typical with intake leaks, and I just tried to identify any leaks using my propane torch but I didn't really hear a change in RPM with that test moving it around the manifold, carb body, etc. I should also say that the o-rings and aircraft style clamps are almost new and in great shape, and just the other day I took the manifold off and re attached it all as sturdy and even as I could, with my carb support bracket.

    I have read that the Super E's can sometimes leak through the throttle shaft. I have had this carb opened up last summer and went through it to clean it out. I bought it used but from a guy who said he had it on his evo something or other for just a few weeks then switched carbs and it sat after that. Like I said I tried the propane torch test and found no change in RPM holding it up around the throttle connection on the carb either.

    People also say in other threads to check advance weights/springs. I have not checked this since getting the motor back from rebuild, but I know the advance unit and weights/springs are new as well as the points.

    Any help or ideas on what to check next would be appreciated, thanks!

  2. #2

    Default

    Try using carb cleaner for checking intake leaks and make a dog cone for the carb so it doesn't suck in any of the carb cleaner mist. An old amazon box works. Pressure testing the manifold with 5 psi is better than either propane or carb cleaner. Make sure to spray the throttle bushings, the enrichener, mixture screw, the carb to manifold area to check the o-ring seals there and then the spigot o-ring clamps. Did you rebuild the carb with a re-build kit when you had it open? The accelerator pump has check balls and o-rings along with the accelerator pump to upper throttle body. The mixture screw has a o-ring on it make sure its there. Even new advance springs can be trash.

    Are you using the carb to body phenolic spacer for preventing the carb from heating up?
    You said the carb came off a EVO does the super E have a VOES port? Is it sealed?
    What is your idle rpm set to?

  3. #3

    Default

    Assuming you have stock points ignition - Check your advance mechanism - worn advance mechanism can hang at full advance and cause these symptoms.

  4. #4

    Default

    Quote Originally Posted by 69Glide View Post
    Assuming you have stock points ignition - Check your advance mechanism - worn advance mechanism can hang at full advance and cause these symptoms.
    Yes stock point ignition, everything recently replaced when motor was rebuilt but I will look anyways.

  5. #5

    Join Date
    Sep 2012
    Posts
    338

    Default

    And, just for the hell of it, lube your cable(s). Can't hurt.

  6. #6

    Join Date
    Sep 2012
    Posts
    12,163

    Default

    Quote Originally Posted by MOTher View Post
    And, just for the hell of it, lube your cable(s). Can't hurt.
    LOL I was just going to say that.......

    Great minds??????

  7. #7

    Default

    Thanks Abbandon. I'll try the test with carb cleaner next. I can't remember exactly but when I rebuild the carb I only replaced a couple pieces because it was clean and in pretty good shape, and I'm pretty sure I was careful about getting it all right with the check balls and o-rings. My mixture screw is what looks to be the early style one, no o-ring. I am using the carb spacer. It does not have a VOES port. I don't know the exact idle because I don't have a tachometer on the bike but it is a healthy idle, not too low not too high.

    I pulled the plugs again today after running it and now the front plug is sooty and black and the rear plug is light tan. Could this mean an intake leak would make more sense in the rear jug/manifold o-ring?

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