Custom Exhausts On Fuel Injected Harleys. The End Of Popping, Spitting And Backfiring.

All bikers want better looking and sounding exhausts increasing performance, throttle response without sacrificing fuel economy. As a matter of fact, year after year, custom exhaust systems are at the top of the wish list of most bikers. But most forget that they will have to re-tune their motorcycles to avoid exhaust popping, spitting and backfiring. If you ride a fuel-injected Harley-davidson motorcycle, one solution is to install a Thundermax self-tuning fuel management system. It will automatically tune your engine for maximum performance – no Dyno required – for any performance upgrades you may do, like pipes, free breathing intake, cams, or other aftermarket parts.

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14 Responses to “Custom Exhausts On Fuel Injected Harleys. The End Of Popping, Spitting And Backfiring.”


  1. 1 Jason Hallman Dec 9th, 2011 at 10:18 am

    I have dealt with Tmax auto tuning since 2007 and I love it. It truly makes your bike the “Dyno” and alleviates the wear and tear that a dyno can put your bike like worn tires, cooked engine oil and unnecessarily excessive engine rpm that can beat the life out of your valve springs. I am not saying there isn’t a place for dynos in the industry, all I am saying is that when not used properly a dyno can do more harm than good. Big bore kits and most large cams will still need a base map other than stock but anyone willing to put in the time will love this system. I train all of my employees on it and I have a Tmax on my personal bike because it works!

  2. 2 Bleeding Ears Dec 9th, 2011 at 11:50 am

    Will it work with REALLY, REALLY LOUD pipes?

  3. 3 Jason Hallman Dec 9th, 2011 at 12:00 pm

    Yes. The Thundermax operates on the: more throttle position/more tuning principle. Which means that the more throttle activity it sees the more adjustments it will make. It if a pipe design is not conducive to promoting good linear torque curves and proper scavenging or not enough back pressure it will most likely conceal that fact. That is where the dyno comes into play. Highly modified engines will most likely always benefit from proper dyno tuning. I no longer own a dyno but I can tell you that for 80% or more of the HDs on the road today with bolt on components inside and out…the Tmax will get the job done better than any other other tuner

    .

  4. 4 Jason Hallman Dec 9th, 2011 at 12:05 pm

    The other thing to bear in mind is that the HD factory system is a narrow band EFI system. This means that the tuning window is very “narrow”. The Tmax is a wide band EFI which means that the O2 sensors are capable of reporting back to the ECM much more precise information and make a lot more adjustments. Nicely put: you could ride from Miami (sea level) to Denver (5280 feet altitude) and by the time you get there you bike has made adjustments to the tune the entire trip. All of us that have ridden for anytime recall changing carb jets due to altitude or weather changes. This makes all of that a thing of the past

  5. 5 Keith Stone & Kiki Dec 9th, 2011 at 2:45 pm

    Another option that works VERY well is the Power Commander with Auto Tune. Similar system with infinite amount of adjustments…. Both systems work very well, we have found PCV & AT have more options…

  6. 6 Watson Dec 9th, 2011 at 3:16 pm

    I installed one on my ’10 sportster 1200 after pipe and air cleaner. Straightforward installation and it works! Perfect fueling and self correcting when I go into the mountains, or when loaded. How great is it to spend money on performance accessories and have them actually work! Rare, I know.
    Oh, and my pipes are loud. I like it!
    Watson

  7. 7 Jason Hallman Dec 9th, 2011 at 6:18 pm

    Keith,
    I agree that the PCV has to be good. Dynojet is (was) the industry standard so it is no suprise that they make a great auto tuner. For the money, I loke the Tmax because of the ECM. I am also unsure whether or not the PCV will log data. EIther way I encourage all of my customers to go with an auto tuner whenever their budget allows.

  8. 8 Boomer Dec 9th, 2011 at 6:56 pm

    It sounds like the PCV w/AT will take a bit more hands on time with the acceptance of trims and dialing out some of the popping that may occur than the TMax if I’m understanding this correctly. The TMax, once installed, needs no other adjustments to correctly tune the bike for the parts installed and the altitude of the environment. Yes?

    If this is correct; I’d have to say the extra cost of the TMax would be worth it.

    Any chance on making the TMax for Victory’s anytime in the foreseeable future? Is it even doable with the different EFI system on the Victory’s?

  9. 9 Rogue Dec 9th, 2011 at 8:40 pm

    I have been using the Thunder Max on my 2009 FLHT using different combinations of exhaust and even a high flow air cleaner.
    After originally installed I rode the motorcycle for 50 miles and it tuned itself.
    When I change exhaust I simply go into the program and tell it what i did and then ride the motorcycle again.
    I ride all over the country attending and covering motorcycle events as well in all kinds of weather conditions.
    I have over 30,000 miles on it since originally installed and have not had any issues.
    I am very happy with Thunder Max and reccomend you try it

  10. 10 A 1 CYCLES Dec 10th, 2011 at 10:01 am

    and everyone should be aware..if you have an air leak an auto tune system no mater whose it is will tune your bike out untill that cylinder doesnt run. you need to go into the system after awhile and turn auto tune off…anf then turn it back on for changing conditions..seen it happen. intake leak front cyclinder bike came in on one cylinder firing…it richened up the front on auto tune so much it fouled the plug..no systemis fool proof and i will never replace my dyno..yes the auto tunes work well with most base systems..but really radical motors and turbos and nitrous require mapping and an experienced tuner

  11. 11 Gerry Dec 10th, 2011 at 12:24 pm

    ’96 Road King , Rhinehardt true duals with O2 sensors, S & S 107″ Evo motor, magneti marrelli injection. Will this work on my bike?

  12. 12 Jason Hallman Dec 11th, 2011 at 3:39 pm

    I believe they make a Marelli conversion kit.

  13. 13 Alan sharp Dec 12th, 2011 at 7:05 am

    Bi H/D EU is going to outlaw modified bike!!!!!!!!!!!!!!!!!!!

  14. 14 Sluggo Dec 12th, 2011 at 5:02 pm

    I personally feel the Thundermax is the best ignition you can buy. I run Samson True Duals and the bike runs perfect with a lot of power. When i do new cams I may have to get a new download but it is so simple my dumb assed sister could do it.

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