103 Big Bore Kit

KingHeritage

I've been considering installing the 103" big bore kit on my '07 Heritage.The local dealer is drumming up winter business with special prices(though I haven't gotten an out the door price yet).I'm already running V+H true duals,SE air cleaner and PCIII.Will this upgrade be worth the money versus the performance I will receive?

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Never make someone a priority when they only see you as an option!

USMCCWO5

My opinion only: No!

If you upgrade the heads with larger valves, port & polish, bump the compression, then you will see a performance gain vs money spent.

However, if the price is right, that might be a good place to start, especially with the right cam choice.

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Semper Fidelis,
James

Hobbit

if you were going to do it use this kit with the cams

Screamin' Eagle® Street Legal Big Bore Stage II Kit for '07-later EFI Models - 103ci

The Stage II Big Bore Kit provides the parts you need to increase the horsepower of your EFI-equipped model. The kit increases the displacement of your Twin Cam-equipped model from 96 cubic inches (1584cc) to 103 cubic inches (1690cc). Includes Stage II (SE-255) cams, Big Bore cylinders, Big Bore flat top pistons, clips, and a Stage I Air Cleaner Kit with one-piece backplate, integral breathers, all mounting hardware, and gaskets. Also includes a high performance clutch spring. Separate purchase of cam spaspacers is required. See manual for proper procedure and cam spacer part numbers. Requires separate purchase of primary cover gasket. Not all components shown. 49-state kits include catalyst mufflers or headers, and California kits are street legal on California pollution controlled vehicles when used with Original Equipment mufflers. All EFI-equipped models require ECM calibration (priced separately). Regulatory approvals pending for '09 California kits.


Twin Cam 96 Stock vs. 1690 Stage I Kit Performance Chart

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USMCCWO5

Good call on the complete kit, especially the clutch improvement.

If someone says they have 100 hp, ask them if they have a stock clutch. I don't think both of them are compatible. My stock clutch didn't make it passed the dyno work. My next stop was Primo-Rivera.

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Semper Fidelis,
James

Hobbit

on my built metric i replaced my clutch before i got to the Dyno - rode 60 miles to Sam Ermenlenko's dyno in Derby (speedway champ) with a 48lb pull Barnett Clutch pack then ripped it up on the DYNO even his neighbours came out to see what was being run as he had to stretch his dyno to get the rear wheel on the roller which mean the sound proof doors were open and with Baffleless Samson Ripsaws,Pod kit, Dyna coils, ignition, 420 grind cams, and sat 3" lower at the rear it took 4 of us to get it on the dyno and then it left me down with its figures (exhaust) 75hp and climbing at 7500rpm and 55ft/lbs swapped to a 2-1 and whooo hooo 80hp -70ft/lbs needed to upgrade to the 64lb pack.
i cannot wait to start engine power on the street bob, my xl1200 would wipe the floor with my metric up to 100 then the metrics higher reving motor took over and it was just about game over

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FishHunter

A great upgrade is to bore to 103"(or to a 3.935" bore, 107") is to compliment that with a Wood 6 or 7H,(requires a valve spring) and have 1.900" intakes installed, and set the compression at 10-10.25:1, along with a Zippers air filter. Big early torque, and with a good exhaust, also have the ability to mark an hp number as well. Good combo.

spartacus55

just had 103 kit installed on my 2007 road king already had rinehart tru duals se hi flo air cleaner and sert. added se flat top pistons, se cylinders. 255 cams, heavy duty clutch spring, assorted springs and gaskets. After dyno tuning went from 67hp and 70 ft/lbs tq to 95 hp and 100 ft/lbs tq runs and sounds great cost 1590 dollars including dyno time.

Hobbit

nice figures ive added heads tot he mix with mine, iknow there whats know as decked heads but i should hopefully see similar numbers

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r2kvet

A couple months ago, I got my Dyna upgraded with the Stage III 103 kit straight from the H-D Racing catalog. Fantastic results. 100HP at 5,500 RPM and above 100 torque from 3,000 to 5,000 RPM. Beside the bigger displacement, I had upgraded the air cleaner and replaced the exhaust for the Screaming Eagle exhaust (for the look not the performance).

Lovely.

R2KVET

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08 Dyna Fatbob 103CI and 100 ponies.
04 Road King Custom 95CI

Hobbit

mine is being killed by the EPA 255cams and SERT as we could not get it to run at the correct AFR was running in the 11 and 12's ie rich and at 100% throttle was 10.3 !!!!!! wasting fuel, we tried the VE tables the AFR the Bias and nothing seemed to affect it, if we could get better cylinder fill i would have a 120+tq monster but the cams does not have enough lift to get the air
but its still running 91hp and 111tq in comparison a 96 stg1 was over 30ft/lbs down and 20hp down and the 103 STG2 2008 bob did with a PCIII and no heads was 10hp and 20ftlbs down on the same dyno and the biggest shock the a destroyer Vrod was down on Torque but obliterated all commers on the HP stages 145hp and still climbing but it ran out of RPMS

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