Page 2 of 2 FirstFirst 12
Results 11 to 16 of 16

Thread: Heritage 103 with Andrews 57h cams

  1. #11
    Join Date
    Jan 2017
    Posts
    13
    Total Downloaded
    0

    Re: Heritage 103 with Andrews 57h cams

    Thanks for that Alex. Now I feel more confident and have a plan of action. Heads first and then a Power Vision tuner with dyno. I’d better start saving as winter is almost upon us ........

    Join the Harley-Davidson Riders Club Great Britain

  2. #12
    Join Date
    Apr 2003
    Posts
    1,656
    Total Downloaded
    49.01 MB

    Re: Heritage 103 with Andrews 57h cams

    Quote Originally Posted by badgerbill View Post
    Heads first and then a Power Vision tuner with dyno.
    You don't have to buy a Power Vision, there is a license scheme that is much cheaper. Most people that own PV's don't use them to their full potential and they end up sitting on the shelf doing nothing. They are a fantastic piece of kit with many functions and displays but unless you're going to have one mounted on your bike for real time monitoring of your engine parameters the license option makes more sense.

    Join the Harley-Davidson Riders Club Great Britain

  3. #13
    Join Date
    Sep 2007
    Posts
    1,625
    Total Downloaded
    29.27 MB

    Re: Heritage 103 with Andrews 57h cams

    Sorry I'm not able to help but seeing what's being said about popping on the overrun, what actually causes it and is it doing harm? Mine does if very often and also when changing gear so I'm starting to worry about it now!

    Join the Harley-Davidson Riders Club Great Britain

  4. #14
    Join Date
    Jan 2017
    Posts
    13
    Total Downloaded
    0

    Re: Heritage 103 with Andrews 57h cams

    Sounds perfect !! I'll be in touch in due course. Many thanks !!

    Join the Harley-Davidson Riders Club Great Britain

  5. #15
    Join Date
    Apr 2003
    Posts
    1,656
    Total Downloaded
    49.01 MB

    Re: Heritage 103 with Andrews 57h cams

    Quote Originally Posted by wilkyman View Post
    what actually causes it and is it doing harm?
    No it doesn’t do any harm, it’s just an irritation to some. Both of my own bikes gurgle more than pop on over run but as they’re not quite stock () that’s to be expected. Popping and banging on over run is caused by unburned fuel igniting while the exhaust valve is open or inside the exhaust system. When you shut off the throttle it reduces the fuel being injected into the cylinder and it’s this that causes the RPM to drop. The fuel supply doesn’t completely stop, it just reduces. Side track for a second – a higher compression engine produces a more efficient combustion process than a lower compression engine because the fuel and air mixture inside the cylinder is more compressed. The molecules are closer together so the flame front travels through them faster. When you shut off the throttle the pressure in the combustion chamber is much less causing the already weaker mixture to burn much slower. The mixture can still be burning when the exhaust valve opens allowing it to expand into the header pipe and continue the combustion process in there. Popping is usually first noticed after the stage 1 tune. It was more than likely always there but the stock exhaust was too restrictive to hear it. A couple of tricks to try are to shut off the throttle fully instead of just half way when slowing down and also none of the blipping action as you change down. That just fools the ECM into injecting more fuel as it thinks you’re going to accelerate. More fuel going to an engine that’s slowing down equals more unburned fuel into the pipes which equals even more popping. If it really bothers you then it can be covered up with a dyno tune or if you’re handy with the tuning software then you can do it yourself just by gradually adding fuel in the zero throttle position of the fuel table. Another major cause of popping is exhaust gasket leaks ...
    Last edited by Fast Lane; 17-05-2018 at 04:49 PM.

    Join the Harley-Davidson Riders Club Great Britain

  6. #16
    Join Date
    Sep 2007
    Posts
    1,625
    Total Downloaded
    29.27 MB

    Re: Heritage 103 with Andrews 57h cams

    Quote Originally Posted by Fast Lane View Post
    No it doesn’t do any harm, it’s just an irritation to some. Both of my own bikes gurgle more than pop on over run but as they’re not quite stock () that’s to be expected. Popping and banging on over run is caused by unburned fuel igniting while the exhaust valve is open or inside the exhaust system. When you shut off the throttle it reduces the fuel being injected into the cylinder and it’s this that causes the RPM to drop. The fuel supply doesn’t completely stop, it just reduces. Side track for a second – a higher compression engine produces a more efficient combustion process than a lower compression engine because the fuel and air mixture inside the cylinder is more compressed. The molecules are closer together so the flame front travels through them faster. When you shut off the throttle the pressure in the combustion chamber is much less causing the already weaker mixture to burn much slower. The mixture can still be burning when the exhaust valve opens allowing it to expand into the header pipe and continue the combustion process in there. Popping is usually first noticed after the stage 1 tune. It was more than likely always there but the stock exhaust was too restrictive to hear it. A couple of tricks to try are to shut off the throttle fully instead of just half way when slowing down and also none of the blipping action as you change down. That just fools the ECM into injecting more fuel as it thinks you’re going to accelerate. More fuel going to an engine that’s slowing down equals more unburned fuel into the pipes which equals even more popping. If it really bothers you then it can be covered up with a dyno tune or if you’re handy with the tuning software then you can do it yourself just by gradually adding fuel in the zero throttle position of the fuel table. Another major cause of popping is exhaust gasket leaks ...
    That's a great explanation Alex, thanks again, and certainly puts my mind at rest. When riding home today, I realised that I asked the question too simplistically, as I already knew it is unburnt fuel, and was thinking of re-phrasing my question slightly to get a better/more detailed explanation - no need now, you've nailed it straight off - and I even understand most of it, so a that's a bonus!

    Join the Harley-Davidson Riders Club Great Britain

Page 2 of 2 FirstFirst 12

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •