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Best heads for a 103

  • Wombat71
    Wombat71
    5 years ago
    Hi all, 
    Thanks in advance for any information, have received excellent advice on here previously.
    2015 Softail Standard
    Screaming Eagle Pro Street Tuner
    HD Burst high performance Air Filter
    Cycle Rama 570-2 cams
    Freedom Performance independence pipes.

    Wanting to upgrade head or maybe throttle body or both, any advice is appreciated 
  • Grease Monkey
    Grease Monkey
    5 years ago
    Jeezy.....now you have opened a can of worms, time to decide what it is you really want, them cams you have, what didn't they give you that you was secretly hoping for? 
  • Wombat71
    Wombat71
    5 years ago
    Hi Grease Monkey
    Yes cams are awesome just thinking few months doing bit more to the girl
  • walka
    walka
    5 years ago
    Stock head are fine , no need to change them 
  • Grease Monkey
    Grease Monkey
    5 years ago
    Quoting walka on 23 Jul 2019 12:26 PM

    Stock head are fine , no need to change them 

    No need to change wheels either but plenty do......as you know lol.
  • Grease Monkey
    Grease Monkey
    5 years ago
    71 you can squeeze that cam in the states to 10.2, over here many will say not so much, talk to hoody about your heads but you need a plan man, my first post question still stands?
  • walka
    walka
    5 years ago
    I’ve not long fitted a S&S 106 hot up kit to my 103 street glide , S&S advertisers it to make 115 Hp with there Heads , my bike makes 110 Hp with the stock 103 heads , I’m not going to spend a coupe of grand for 5HP
  • Grease Monkey
    Grease Monkey
    5 years ago
    Quoting walka on 24 Jul 2019 10:42 AMedited: 24 Jul 2019 11:12 AM

    I’ve not long fitted a S&S 106 hot up kit to my 103 street glide , S&S advertisers it to make 115 Hp with there Heads , my bike makes 110 Hp with the stock 103 heads , I’m not going to spend a coupe of grand for 5HP

    Horsepower is expensive, no doubt about it, depends what you are after.
  • Krash Kinkade
    Krash Kinkade
    5 years ago
    Nothing wrong with the 103 stock heads, but those same heads are also on 74 cubic inch Sportsters. So with 103 inch would make quick HP & TQ but probably freeze up early. Leave stock exhast valves, put larger intake valves get bit more.
    There is more to it than just saying you have 110hp now and don't think 5hp would do much.
    But say that 110hp took WOT 10 seconds to show up & the 115hp took WOT 5 seconds to show up. You would feel a big difference especially if the 115hp also made more Torque quicker too
  • Jay-Dee
    Jay-Dee
    5 years ago
    Quoting walka on 24 Jul 2019 10:42 AMedited: 24 Jul 2019 11:12 AM

    I’ve not long fitted a S&S 106 hot up kit to my 103 street glide , S&S advertisers it to make 115 Hp with there Heads , my bike makes 110 Hp with the stock 103 heads , I’m not going to spend a coupe of grand for 5HP

    S&S may undersell them a little too so they don't get complaints, they may very well make 120 or even slightly more in your case and definitely more through the range. As you probably already know dyno numbers can vary quite a bit as well.

    Stock heads aren't shabby but S&S are better and a well ported set of stock heads are even better again. It comes down to budget and choice but a good set of cylinder heads are a must if you're serious about making power.

    OP, I expect decent heads would net you more gain than a TB alone and both are probably better but it depends if you want the spend.
  • Wombat71
    Wombat71
    5 years ago
    Thanks for the input everyone, I am not mechanically minded and what I want is more low to mid range power. 
  • Grease Monkey
    Grease Monkey
    5 years ago
    Could do what walka did, more cubes, keep your cams, tune it, depends on what you want, a bit more low and mid is kinda vague, got any figures in mind? low stress power or hang on type of deal?
  • robots
    robots
    5 years ago
    go to 106 or 107 
    you wasting money on getting heads as most of the gain will typically be above 3500rpm, most don't get up over that often

    drop down a gear to get it going a bit more
  • Rivo
    Rivo
    5 years ago
    Quoting robots on 25 Jul 2019 11:36 PM

    go to 106 or 107 

    you wasting money on getting heads as most of the gain will typically be above 3500rpm, most don't get up over that often

    drop down a gear to get it going a bit more

    I agree in going bigbore, they even do a bolt on 110 now, although I have no experience with them but S & S usually do there homework before putting out on the market...................

    https://www.sscycle.com/feature/performance-kits/power-package/100-110-power-package-big-twin



  • tussuck
    tussuck
    5 years ago
    Turbo.....say no more
  • Grease Monkey
    Grease Monkey
    5 years ago
    Big dumb power = cubes, nothing wrong with the Harley 110 cylinders except the price, S&S, I've used the 106 kit with good results, not used their 110 kit but I'm sure it's good quality as well.
  • tussuck
    tussuck
    5 years ago
    Why not just go 120 or 130 instead?  Is the price differential big or small?
  • Grease Monkey
    Grease Monkey
    5 years ago
    Quoting tussuck on 26 Jul 2019 12:52 PM

    Why not just go 120 or 130 instead?  Is the price differential big or small?

    Going over 110 on a 103 means boring the cases, a few dollars involved.
  • Grease Monkey
    Grease Monkey
    5 years ago
    Quoting Wombat71 on 23 Jul 2019 03:33 AM

    Hi all, 

    Thanks in advance for any information, have received excellent advice on here previously.
    2015 Softail Standard
    Screaming Eagle Pro Street Tuner
    HD Burst high performance Air Filter
    Cycle Rama 570-2 cams
    Freedom Performance independence pipes.

    Wanting to upgrade head or maybe throttle body or both, any advice is appreciated 

    I know this was a month back but if you drop a 110 kit on it and tune it again you will get something like this .....
    Headwork can carry the torque further right lifting the HP a bit.
    image000000_11.jpg
  • noctm
    noctm
    5 years ago
    Quoting Krash Kinkade on 24 Jul 2019 11:17 AM

    Nothing wrong with the 103 stock heads, but those same heads are also on 74 cubic inch Sportsters. So with 103 inch would make quick HP & TQ but probably freeze up early. Leave stock exhast valves, put larger intake valves get bit more.

    There is more to it than just saying you have 110hp now and don't think 5hp would do much.
    But say that 110hp took WOT 10 seconds to show up & the 115hp took WOT 5 seconds to show up. You would feel a big difference especially if the 115hp also made more Torque quicker too

    i might be misreading what you're saying, but 103 twin cam heads are not at all the same heads on the 1200cc/74ci sportsters. even putting the old 1340 big twin evo heads on sportsters, which people did do, required significant modification? 
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