Zipper’s New Muscle 107” Kit For Twin Cam® Engines

Zippers107-1Zipper’s has carefully developed a new Muscle 107″ Kit for Twin Cam® engines  with optimized compression, porting, camshaft design and inlet flow, Combined with their best-in-class finish work, extensive dyno and ride testing, it provides a very balanced engine kit that will not disappoint. The Zipper’s Muscle 107 delivers fantastic power curves with both torque and horsepower reaching north of 120.

Zippers107-2This power is very smooth and broad, with torque over 100 ft/lbs from below 3,000 RPM’s to above 6,000! Kit includes CNC porting with premium components on your heads, fitting forged, 3.937” bore domed pistons to your cylinders, Red Shift® cams and dual piston cam chain tensioners, Axtell oil bypass valve, Pro-Taper pushrods, quality gaskets, high flow injectors and MaxFlow air cleaner assembly with a pre-programmed
ThunderMax® EFI controller.

TBW models require separate purchase of H-D® Screamin’ Eagle® 58mm throttle body (not included); everything else you need is supplied in a single part number/ More info at 410-579-2828 or Zipper’s Performance Products Muscle 107” Kit.

13 Responses to “Zipper’s New Muscle 107” Kit For Twin Cam® Engines”


  1. 1 Sharkey Nov 15th, 2014 at 10:21 am

    Have had a number of HD engines built over the years; this looks like a decent combination…these motors are better at 2000-5000 rpm torque than 6000+ rpm horsepower.

  2. 2 Brad Nov 15th, 2014 at 10:24 am

    Trust Zipper’s for great kits that will not disappoint. Got one of theirs installed by my dealer.

  3. 3 HD Rider Nov 15th, 2014 at 10:24 am

    Finally Zippers comes out with a 107″ kit for the 96″/103″ bikes — I wonder when S&S will follow suit? Seems that when I questioned both companies about why they only offered 106″ kits instead of what seemed to be a proven 107″ kit from others, the stock answer was always that they didn’t feel there was enough cylinder wall thickness left to bore stock cylinders to 107″ (even though the independents had been doing this reliably for years). I’ve been reliably running bored 107″ cylinders in both my bikes for years. Looks like Zippers finally saw the light — or maybe did this to stay/become competitive with what the industry was already doing. I wonder what there story is now about the cylinder wall thickness — surely they won’t admit they were wrong.

  4. 4 Patrick Gross Nov 15th, 2014 at 10:26 am

    Let’s Zipper’s answer.

  5. 5 P. Hamilton Nov 15th, 2014 at 10:27 am

    107″ Twin Cam should interest quite a few.

  6. 6 Mike Nov 15th, 2014 at 12:15 pm

    S&S is selling a 107 conversion kit for the TC96/103 motors, alongside their existing 106″ kits. That was probably a marketing decision, since the real world difference between identically built 106 and 107 motors would be negligible.

  7. 7 Nomadmotorbikes Nov 15th, 2014 at 12:55 pm

    I have had no issues with a bore under 110 inch as long as you run a good synthetic oil like amsoil

  8. 8 Avgjoe Nov 15th, 2014 at 2:13 pm

    Whether it’s a 3.927 bore (105.98″) or a 3.938″ bore (106.57″) you will never feel the difference between the two. Just less cylinder wall.

  9. 9 Greeko Nov 16th, 2014 at 1:16 pm

    Nice to see that contrary to others, Zippers publish a dyno chart.

  10. 10 Zenaldo Nov 16th, 2014 at 3:22 pm

    You’ll never notice the difference..its all about marketing…they’re both going to feel the same in the seat…qibbling about nothing here..

  11. 11 SIGFREED Nov 16th, 2014 at 3:31 pm

    The fact that you have an initial ‘torque drop’, followed by a reasonably rapid rise in torque and power, means it is a motor for experienced riders.

    Std HD motors are forgiving and suits a wide range of riders – eg a reasonably flat torque curve (ie moderate rise); iow no surprises for those who prefers rodeo to remain in the lyrics of cheesy country songs…

    That said – this 107 in a late model Wide Glide (with decent suspension bits) sounds just like my kind of unruly beast. Giving it the beans from ~2750 rpm should be sweet rush.

  12. 12 Taco Nov 17th, 2014 at 9:36 am

    S&S only! Since 1958

  13. 13 Chris Nov 24th, 2014 at 4:40 pm

    The S&S 106″ and 107″ kits use different pistons with the 107″ kit yielding a higher compression ratio. Cam choice may be the determining factor when choosing between the kits.

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Cyril Huze