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  1. #1
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    Default Super E Kick Only Ironhead Rough Start

    Have a '76 XLCH kick only with a Super E and 2 inch drag pipes. Brand new 66 Main, 29 Intermediate. After market bird deflector with no air filter. Dynatek ignition and 5 ohm coil. Spark is a thick healthy blue. Have real trouble getting her started. Carb is set to factory settings and will eventually kick over. Prefers a SLIGHTLY higher idle speed. Checked intake for leaks and there are NONE. When bike starts, she runs cold (cold air out the pipes) until idled for a while or run around the block. Will go back to blowing cold during idle when settled and sitting. Will idle without dying, but runs rough. Eventually found that if I took the bird deflector off, and COMPLETELY covered the intake on the carb with my hand, it would start pretty readily. Revs fine slowly, but bogs when throttle is cracked open.

    Is this a fuel issue (running lean)?
    Could it be the float bowl height?
    Do I need to remove the auxiliary bowl vent?
    Am I an idiot?

    I know that a Super E on an Ironhead with straight pipes and minimal air restriction will inhibit ultimate performance, but this is what I got and I'm sticking to it (not enough $$$ to make life easy).

    How do I tune this fucker to get a clean start and healthy idle with consistent performance?
    Last edited by BlackThumbClan; 07-23-2020 at 11:17 PM.

  2. #2
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    The two inch drag pipes are making your life harder. First thing to do is get rid of them, or the alternative is yeah, you may be an idiot.

    On a small motor, it is sometimes necessary to make the intermediate jet on a Super E much larger than what might appear reasonable. The reason for this is that the velocity of air through the carb is lower because of the smaller displacement of the motor. So, your situation might improve with a 31 or even a 33 intermediate jet. You may have to increase the size of the main air bleed for clean carburation. BUT, until you get rid of the completely unsuitable pipes, tuning may prove impossible.

    Jim

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    Good info^^^,as always.

    Maybe some 'lolli-pops?

    Making Drag Pipes Work

    "If you insist on using drag pipes on your bike, there is something you can do to improve the low and mid range power produced by the engine. Even with the improvement listed here, the streetable engine power is not going to match power output of a good 2-1 or 2-2 exhaust system. Motorcycle Performance Guide does not recommend drag pipes or porker 2" pipes for serious street engines, but the performance fix listed here will improve the power of your drag pipes. Results have been confirmed by dyno results...

    If your taste in bike styling requires that drag pipe must be used, there is some hope to getting back some of that lost low to mid rpm power. Here is a poor boys trick that will make your drag pipes work much more effectively. This setup can actually be tuned to meet the performance needs of the bike...

    Make a tunable baffle by purchasing a 1/4"x1" thumb screw or taking a 3/4" outside diameter washer and weld it to the top of a 3/4" x 1/4" bolt.
    Now Drill a 1/4" hole about 1" from the end of the drag pipes.
    Take the tunable baffle and place a 1/4" nut and a lock washer (away from the large washer) the on it.
    Now insert your tunable baffle into the exhaust pipe like the example below...
    Click image for larger version. 

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    You can tune the baffle by changing the angle of the thumbscrew or washer to the exhaust pipe. For maximum torque, the washer will be at 90 degree angle to the pipe. For maximum horsepower the washer will be parallel to the pipe.

    How well does this work?

    Bike Tech received a dyno run sheet from Gene P. that just showed what happened by changing the angle of the thumbscrew. Three runs were done.
    Thumbscrew parallel to the pipe (run 7),
    45 degrees to pipe (run 6) and,
    90 degrees (run 5) to the pipe. Judge the results for yourself.
    This also shows you the benefits of dyno tuning something as simple as your exhaust system.

    Run 7 (open or parallel to the pipe) Makes the most power, but has a huge hole in the power band just above 3000 RPMs

    While run 5 makes the lowest horsepower (approximately 68), the 2500-4000 RPM power is the highest. This is the RPM band that most riders spend there time riding.

    Run 6 improves the 3000-4000 RPM horsepower drop over run 7 without any significant drop in maximum power.
    Where did this come from?

    This isn't some new technology that was just discovered. Any rider who remembers the Honda 250 and 305 Scramblers of the 70's should be quite familiar with the technology. In addition to tuning the power band, it also adjusted the amount of noise that came out the exhaust pipes. It was a well know trick when it was done by Honda.

    For those of you who are willing experiment more, the size of the washer can be increased as can the size of the hole in the washer. A strong spring can be used to hold the washer in place in relationship to the pipe and a "wing nut" arrangement can be used to adjust the angle of the washer.
    I want to thank Terry for remembering this trick and bringing it to my attention. He was looking for some additional power from this bike. The cost of a new set of pipes was not in his budget at the time so the following suggestion was made by the Motorcycle Performance Guide staff

    "If you want to use the 'poor boy' trick to make your drag pipes work better, just drill a 1/4" hole about 1" from the end of your drag pipes then put a 1 1/4" by 1/4" bolt through it with the shaft inside the drag pipe. Place a about 1/2" of washers inside the exhaust on the bolt then add a lock washer and nut. Tighten it down and take if for a ride. This should improve the mid range power, and it might have cost you $2.00 . You can actually tune the power range a little by adding or removing washers, or altering the length of the bold. Cheap Trick!!"

    Terry responded back with the following message:

    "I tried that and it made some difference but not tremendous. I then took a 1/4" x1" bolt and welded a 3/4" diameter washer to the head of the bolt so it looked like a candy sucker. I used a nut on inside of pipe and a nut on outside of pipe with "sucker " inside the pipe. By turning the "sucker", could vary amount of resistance to exhaust flow. I ended up with washer flat across pipe for maximum resistance. That made a TREMENDOUS difference in mid range power and quieted it very slightly. Unbelievable difference! Don't have a dyno to provide numbers, but I KNOW it's much quicker."

    We appreciates Terry's efforts. It's the little tricks like this that help all riders. If you have a tip that solves a performance or maintenance situation, E-mail us with your suggestion..."

    http://www.nightrider.com/biketech/exhaust.htm

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    Lollypops are a crutch for pipes that are the wrong length, or to try to broaden the useable torque range when using drag pipes, cam, and carb that are not really compatible.

    Two inch drag pipes on any motor under 100 cu in. results in velocities so low that tuning is practically impossible. Pipe restrictions are not going to help that problem.

    Jim

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    Quote Originally Posted by JBinNC View Post
    The two inch drag pipes are making your life harder. First thing to do is get rid of them, or the alternative is yeah,
    You may be an idiot.

    Lol ... No sugar coating here ....

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    Quote Originally Posted by Dragstews View Post
    Lol ... No sugar coating here ....
    His words, not mine.

    And I said "may be", not "are."

    But the point is valid, no?

    Jim

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    Quote Originally Posted by JBinNC View Post

    But the point is valid, no?
    .. Indeed ..

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    Compare air velocity for a whistle and a yawn. S&S are somewhat oversize for a stock Ironhead but a lot of uninformed choices were inflicted on Ironheads. I run them on big twins but that's really so I have a standard carb for the fleet and can grab a spare if one needs cleaning. The Keihin CV is a MUCH better Sportster carb and it's easy to sell an S&S if you decide to swap.

    I'm gonna say something somewhat controversial but likely to save you major money and pain since cash is tight. Unless you already own another RELIABLE motorcycle I would choose the path of least expense and sell the Ironhead before it eats your wallet. They are NOT modern motorcycles and can often be more expensive to work on than a big twin. One way to get around having to start it is parting it out. If they weren't born with the Harley name they'd be as forgotten as an Allstate twingle. OTOH a great HD engine for reliability is the five speed Evo Sportster.

    You won't see a lot of professional HD mechs daily an Ironhead. I've never known one personally who did except in their youth when that was all there was.

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    You can make an air cleaner for real cheap using universal one from any auto store. Or pickup a used one. I'd definitely recommended an air filter.

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    Like most people said already. You have took much air on both ends to ever tune it right. You're basically running big twin stuff on a much smaller motor.

  11. #11
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    There's a Bendix for $35 in the classifieds that's a cheap start to a solution

  12. #12
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    Thank you all for the detailed and helpful responses.

    Update: The bike kick's over very easily when I completely block off the carb with my hand for one kick, and then kicks right over on the second.

    I tuned the carb to a healthy idle and the bike is running well. I'm running into some issues with the low end rpms and think that a jet change might be in order.

    And yes, JBin, I am an idiot, and your information and depth of knowledge has been EXTREMELY helpful along my journey. THANK YOU.

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    Quote Originally Posted by BlackThumbClan View Post
    Thank you all for the detailed and helpful responses.

    Update: The bike kick's over very easily when I completely block off the carb with my hand for one kick, and then kicks right over on the second.

    I tuned the carb to a healthy idle and the bike is running well. I'm running into some issues with the low end rpms and think that a jet change might be in order.

    And yes, JBin, I am an idiot, and your information and depth of knowledge has been EXTREMELY helpful along my journey. THANK YOU.
    I hope you got rid of the 2" drag pipes.

    Jim

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    .

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    I think that reversion is the reason you think the pipes are blowing cold. Every time an exhaust pulse leaves the pipe it creates a vacuum in the pipe and sucks back air from the atmosphere, which has a cooling effect on the pipe.
    It travels back toward the exhaust port until the next time the valve opens and releases another high pressure pulse. If and when it happens that the reverse pulse is hitting the port at about the same time as the exhaust pulse then it actually fights the exhaust pulse and hinders the exhaust, forcing some of it to stay in the cylinder and occupy the space needed for a complete fill of air/fuel, thereby killing power at that rpm range.
    Reversion happens on a larger scale with larger pipes.

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