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The Viking
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Discussion Starter · #1 ·
Hello to everybody. Hope you have all had a good Christmas.

Surfing the web today came across this item.

Being a novice can anybody enlighten me, as it seems to go against all the advice given for engine upgrades:hmmm:




Smaller ports on Harley Davidson

V i e w e r F e e d b a c k
Yo MotoMan:

I've been reading your e-columns for a while with some considerable amusement. I'm finally compelled to write because of the reference in your latest issue to Harley-Davidson motors & the question of whether small ports would work in that application.

I road-race a Buell which, of course, is fitted with a H-D Sportster motor which comes with upgraded heads, cams, pistons. In stock tune it delivers approx. 85 h.p. and 80 ft/lbs of torque at the rear wheel. Virtually ALL Harley race tuners use typical small-block Chevrolet NASCAR-type technology to build race motors on this platform (read: BIG cams, BIG ports, LOTS of squeeze). They then spin the motors at 8,000+ rpm to make it all work. Bearing in mind the H-D V-twin motor is basically an over-sized air compressor, the results are predictable: manifestly unreliable motors which struggle to keep up with Ducs, RC51's, etc., etc. They typically make 110 h.p and 90 ft./lbs. of torque (rear wheel) with very narrow power bands.

After a 2 season alliance with a local Harley dealer (with a lot of racing experience) resulted in nothing but innumerable broken parts (including one spectacular exit of a con rod through the transmission resulting in a lurid rear wheel lockup and slide for a couple hundred ft. but, Hey!, I didn't fall down..) and major expense, I went looking for a different solution. I found it in the person of a Mr. Bob Johnson of J.E.T. in Westerly, Rhode Island. He has a fascinating background in leading edge automotive head design, but currently does only one-off customer engine projects, both bikes and cars.

To make a long story short, Bob built a new race motor for my Buell based on his research and applied mathematics to produce the best port velocity and cylinder-fill characteristics, i.e. small ports. In fact, his research, and empirical testing reveals that the most powerful cylinder head Harley makes (regardless of engine size) is their "little" 883 head. He has made 100 h.p. in testing by simply bolting (with some minor modification for fitment) a set of 883 heads on a big twin (1340) motor with appropriate cams.

And now the BIG QUESTION: how does my motor work???? At 10.1:1 compression, Red shift 567 cams, 44CV carb, modified intake manifold (to straighten the runners out), the puppy makes (rear wheel) 108 h.p, @ 6800, 100 ft./lbs. of torque @ 4500. 86% of max torque is available between 3,000 and 6800; the acceleration curve of the motor is nearly vertical, oil temp never exceeds 150 degrees, it runs on pump gas. Not a single mechanical failure. The bike pulls like Jack-The-Bear, blowing off Ducati's, Hondas, Suzuki's, everything in the class. We have so much torque available (and THAT'S what moves the bike, not h.p.), we're considering replacing the 5 spd. Trans with a 4 spd. I really only need 3 race gears and a low for the pits/start line. The bike is much easier to ride fast because the torque is available everywhere and is smoothly predictable, unlike the typical H-D race motor which is tuned to produce h.p. waaay up in the corner of the power curve.

Bob calculates there's another 10 rear-wheel h.p. in the motor by going to even smaller ports (I presently am running 1203 'Thunderstorm' heads modified by Bob to shrink the ports) with 883 heads and more cam, but the power delivery would be more radical and would probably require a slipper-type clutch to be rideable (due to deceleration compression). I haven't gone that extra step simply because I don't need any more power!! (Imagine that!).

Sooooooo MotoMan ???
The answer is, YES small port technology works on two valve motors, and specifically H-D motors !!!

Hope you find this interesting

Cheers !!

~ Robin
---------------------------------------------------------
Hi Robin !!

Thanks for the incredibly encouraging info, I'm suddenly starting to turn "orange and black" !!! I want to work on some Harleys !! Look for more info in upcoming Power News issues about the mighty V Twins from Milwaukee !!

~MotoMan
 

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Don't tell H-D that smaller ports work better. 1999 - 2005 heads had a 1.340 exhaust port and in 2006 it is 1.570 I agree that small ports work better and have more velocity.
 

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Well that same theory was explained to me a while back.

The summary being that it is better to have a smaller managable amount of air move at a higher velocity through the engine, than a large unmanagable amount of air moving slowler. The faster the air gets in and out, the cooler the engine runs and the more usable torque it produces.

The heads with large ports produce great numbers only at Wide Open Throttle. So to compensate for that and give more usable torque, some heads are made with the ports, machined in such a way that there is a hump like small ramp built into the port area to squeeze the flow ever so slightly to build up velocity. This equates to placing your thumb over the flowing garden hose to make the water come out faster and shoot farther and stronger, hence velocity and torque.

So a smaller port helps the air move faster through the engine. Having the heads "cleaned up", or smoothed out lets the air flow with less drag and turbulence. The same principle applies to the valves. Larger valves move a lot of air in and out. Smaller valved that are polished cut, and faced a certain way, move the air in and out with less combustion turbulence, quicker and at greater velocity.

Properly packaged, all of this translates to a cooler running engine, that produces torque over a larger more usable band.

Your findings may be different, but this is what I have learned.

Mark
 

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The Viking
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89 Posts
Discussion Starter · #5 ·
Looking to upgrade from 85" to 95" and hoping do the following mods:-

fit se flat top cast pistons.
rebore pots to suit
fit 44mm cv carb.
fit andrews 37g cams.
se ignition 6200 rpm module
new heads by dewey


somebody help!!!

you read one thing saying that head porting is the way to go then this saying the opposite:huh:
 

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Mickyo said:
Looking to upgrade from 85" to 95" and hoping do the following mods:-

fit se flat top cast pistons.
rebore pots to suit
fit 44mm cv carb.
fit andrews 37g cams.
se ignition 6200 rpm module
new heads by dewey


somebody help!!!

you read one thing saying that head porting is the way to go then this saying the opposite:huh:
I'm sorry to have confused you, all I was doing was posting my findings and my expereince.

Since you want to go with Deweys Heads, I suggest you contact Dewey and tell them of your proposed build. Tell them the kind of bike you have, your current mods, and your future mods. Let them know if you want mild and dependable, or a full out drag racing hopped up track bike. Tell them if you want a neat sounding bar hopping head turning bike. Tell them where you like to ride, and where you want your torque band. Some folks run WOT all the time and don't mind a loping idle that sounds like it's going to stall. Some folks like to cruise and only want torque to pass and for mountains. Some want low end off the line tree stump pulling torque. Tell them if you ride two up, or solo. If your trips are short, or long cross country. A full dressed Ultra is much heavier than a Dyna, as as such needs torque in a different range.

Chances are they will have a package that they suggest. While the parts may not be what you have in mind, their package is most likely a proven combination that they have found to work through countless builds.

If you are not fully decided on Deweys, then consider any of the below listed builders. Someone here or on another fourm has used them with success.

The important thing is to find a builder and stick with their package. Do not try and go with a cam recommendation from one, heads from another, and so on. And remember, each one may suggest a exhaust set up to work best with their combo.

Good luck!

AMS
212 Carroll St
Ft. Worth, TX 76107
1-800-210-8675
http://www.automotivemachine.com/

Dewey's Custom
3108 Pontiac Drive
Farmington, New Mexico 87401
505-326-5998
http://www.deweyspegs.com/products.html


Baisley Hi-Performance
5511 N. Interstate Ave.
Portland Oregon 97217
(503)289-1251

Hal's Speed Shop
1915 S. Moorland Road
New Berlin, Wisconsin 53151
262-814-7282
http://www.halspa.com/default.asp?P=2

Nallin Racing Head Service LLC
3770 Puritan Way Unit E
Frederick, CO 80516
(303) 833-4500
http://www.nrhsperformance.com/headworktc.shtml

Head Quarters
Parts Order Line 519-892-6992
Tech Line 519-892-6999
http://www.head-quarters.com/


Bishop Performance
26448 Grand River Ave.
Redford, MI 48240
313-537-5026
http://www.bishopsperformance.com/heads.htm

Full Sac
Lake Havasu City, Arizona
928.505.2912
http://www.fullsac.com/products_cylinder_port.htm

Engines by Otto
Sugar Grove, IL
(630)466-3900

Big Boyz Cycles
685 Riverside Dr.
Augusta, ME 04330
207-621-1001
http://www.bigboyzcycles.com/

Richard's Engine Developement
16-3 Bonny Eagle Road
Standish, Maine 04084
207- 221-0765
http://www.sacoriver.net/~red/index.html

R&R Cycle
Manchester, NH
603-645-1428
http://www.rrcycles.biz/

Hillside Motorcycle & Machine
5225 S. Main St.
Munnsville, NY 13409
Phone (315) 495-6650
https://www.websitedesignpros.us/hillside/hillside/frame.asp

Short Block Charlie
2015 E 5th Street #18
Tempe, AZ 85281
800-597-0922
http://www.motorcyclemachine.com/services-hdperf-packages.html

Hardy Heads
1534 N. State College Blvd.
Anaheim, CA 92806
714-490-0155
http://performancetechniques.com/hardeyhead9/index.htm

Hemi Design
3147 South Austin Blvd.
Cicero, IL 60804
(708) 652-5450
http://www.hemidesign.com/

Revolution performance
1312 Pilgrim Road
Plymouth, WI 53073
Toll-free: 888-779-6885
920-892-2109
http://www.revperf.com/twin.aspx?action=cylHeads

Dave Mackie Engineering
2065-H Sperry Avenue
Ventura, California 93003
Tel: 805-658-6969
http://www.davemackie.com/

FLO Headworks
1150 Pike Lane, #2,
Oceano, CA, 93445
805-481-6300
http://www.floheadworks.com/Default.htm

JET
10 Springbrook Rd
Westerly, RI 02891
401-595-9507
http://www.johnsonenginetechnology.com/JETPAGES/packages/95_twin_cam_fuel-injected.html

BC Gerolamy
3322 Luyung Drive
Rancho Cordova, CA 95742
916-638-9008
http://www.bcheads.com/twin.htm

John Sachs, Sachs Race Bikes
Ft Lauderdale, FL
954-473-2980

Bob Wright, R&D Performance
952-955-1198

Leo Hess, Full Blast Engineering
605-332-2659

Cycle Rama
7200 73rd Street N.
Pinellas Park, Fl. 33781
727-546-0889 / 727-546-0945
http://www.cycle-rama.com/HPProducts.html
Port Pros
12108-C Roxie Drive
Austin, TX 78729
512.257.0222
http://www.portpros.com/HarleyDavidson.html

Big Al’s Performance Parts
110 John King Rd
Crestview FL 32539
704-425-0411
http://bigalsperformanceparts.com/

Underground Performance
Strathmore, Alberta, Canada T1P-1K1
403-901-1000
http://www.undergroundheads.com/

T-Man Performance, Inc.
205 Pitts Street
Kernersville, NC 27284
(336) 993-7068
http://www.tmanperformance.com/

Lee's Speed Shop
12450 Hwy 13 S
Savage, MN 55379
952 233 2782
http://leesspeedshop.com/

Branch Flometrics
5556 Corporate Drive
Cypress, CA 90630
714-827-5340
http://www.branchflowmetrics.com/Introduction.htm
 

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The Viking
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Discussion Starter · #7 ·
Paniolo


thanks for the info. Being a novice, and reading all the info out there you kinda get an idea what it is you want in your build................until you read articles from this motoman guy. He does seem prety clued up. I'm still at the planning stage with my build and want to get it right (1st time preferably:) )Apart from that don't fancy spending $1000 plus for something if I don't need it.

God I love this site!!!!
 

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head work

I'm running a 95" with SE 203 cams, Vance and Hines SBS and SE air cleaner. Been considering head work to further enhance performance. Very interesting on the smaller valves, because virtually everyone (S&S, Branch, etc.) that modifies heads for HD installs larger valves as part of the head porting process. They all publish their results. If power is what we're all after why don't they do the small valve technology for at least some applications (like for torque freaks?)

So who is right? Is anyone willing to take a stand on this? Is this a can of worms or what?

Great forum, thanks!!

John
 

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Well answered Paniola.............................Ozzie

Of course Dewey and GRock have found what I believe to be the optimum in Valve size and port diameters.

The software program I have been running for quite some time now shows me that there is an all round optimum size out there.

Going slightly up or down just rocks the HP/TQ results up or down..........so the decision becomes yours as to cafe racer or torque monster.

Have to repeat this again too in that Dewey is the only guy out there that I am aware of that is performing work on the valves that effects the low to mid transistion of port flow and velocity which all engine power builds up from.

All the best, Ozzie.
 

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The Viking
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Discussion Starter · #10 ·
I'm running a 95" with SE 203 cams, Vance and Hines SBS and SE air cleaner. Been considering head work to further enhance performance. Very interesting on the smaller valves, because virtually everyone (S&S, Branch, etc.) that modifies heads for HD installs larger valves as part of the head porting process. They all publish their results. If power is what we're all after why don't they do the small valve technology for at least some applications (like for torque freaks?)

So who is right? Is anyone willing to take a stand on this? Is this a can of worms or what?

Great forum, thanks!!

thats exactly how I feel John @gree:


Mickyo
 

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I'm running a 95" with SE 203 cams, Vance and Hines SBS and SE air cleaner. Been considering head work to further enhance performance. Very interesting on the smaller valves, because virtually everyone (S&S, Branch, etc.) that modifies heads for HD installs larger valves as part of the head porting process. They all publish their results. If power is what we're all after why don't they do the small valve technology for at least some applications (like for torque freaks?)

So who is right? Is anyone willing to take a stand on this? Is this a can of worms or what?

Great forum, thanks!!

John
Welcome to the forum John, it is the overall package that works.............the combination as a whole.

Bigger valves and ports produce the power at the top end with a sacrifice to the bottom end............with the appropriate shorter gears these builds in light bikes are awesome..........but are flighty and need good to excellent rider skills in bikes that have stock HD steering geometry and suspension.

Slightly bigger valves with the correct port size with mid duration cams are good allrounders............that still need suspension mods to help with the added power.

Smaller ports with short duration/high lift cams like the TW5 are a blast.......put out heaps low down manageable power, break the rear wheel out at will, lift the front wheel as well, and are more manageable and really do work in the rideable range of rpm (2000/4000)

Food for thought...................Ozzie
 

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I'm running a 95" with SE 203 cams, Vance and Hines SBS and SE air cleaner. Been considering head work to further enhance performance. Very interesting on the smaller valves, because virtually everyone (S&S, Branch, etc.) that modifies heads for HD installs larger valves as part of the head porting process. They all publish their results. If power is what we're all after why don't they do the small valve technology for at least some applications (like for torque freaks?)

So who is right? Is anyone willing to take a stand on this? Is this a can of worms or what?

Great forum, thanks!!

John
It's not a can of worms, but like "oil", you will get different answers from folks that have all had success and failures with diffeent combos. That is why I said to decide on how you want your bike to run, where you want your torque, all based on your riding style. No two people are alike. No two builds are alike. You can take the exact same bike, put in the exact same parts, built from the same shop, and they will produce different numbers on a dyno.

Which brings me to my final thought. Don't get caught up in the dyno numbers game. Just tell the builder how you ride, and what you want. Then don't get bent out of shape if the dyno numbers are not what you expected (they never are), or are not equal or better than another bike with the same build. It's how it runs and if you like it that matters.

Mark
 

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Mickyo,

Don't get confused that "porting" means hogging out a couple pounds of metal. "Porting" is a general term that really, at least to an experienced porter, really means being able to simply pack more air and fuel in the intake charge on each stroke. That takes velocity! I've seen so many guys LOSE power with big ports, big valves, wrong radius, etc. Bob Johnson, who I've known for several years, beleives in velocity and is able to do very good work. But he ain't cheap. And he ain't the only one who follows this philosophy. Many good porters have known this for years. Dewey Custom's and I went back and forth last year with testing for some 107 and 114 builds and had no larger than a 1.590 exhaust that produced the best results. Heads were ported slightly and Dewey did some of that magic shitt that he won't tell anyone about, but some of the builders around here were telling me we were crazy. Well after a bunch of runs and a bunch of back and forth on re-works and modifications, we have a combo that develops tremendous power and throttle response. My own personal 107 develops 115 HP and 125 TQ and hops off the line like a frog on a hot plate. All the guys that are suggesting 1.625 or 1.687 exhaust valves and 2 inch intakes can have them. Bigger is not better. Now if you are thinking of leaving your stock heads alone because maybe you are confused about porting, then you are costing yourself anywhere from 10 - 14 HP and TQ (although maybe not that much with the 203). But smoother, cooler running and better low end manners and throttle response await you if you make the right decision on a porter.

Good luck in your quest for power!
\
G
 

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SILVER BULLET said:
Don't tell H-D that smaller ports work better. 1999 - 2005 heads had a 1.340 exhaust port and in 2006 it is 1.570 I agree that small ports work better and have more velocity.
Which heads?? Sportster or Twin Cams
 

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common sense advice?

Paniolo said:
It's not a can of worms, but like "oil", you will get different answers from folks that have all had success and failures with diffeent combos. That is why I said to decide on how you want your bike to run, where you want your torque, all based on your riding style. No two people are alike. No two builds are alike. You can take the exact same bike, put in the exact same parts, built from the same shop, and they will produce different numbers on a dyno.

Which brings me to my final thought. Don't get caught up in the dyno numbers game. Just tell the builder how you ride, and what you want. Then don't get bent out of shape if the dyno numbers are not what you expected (they never are), or are not equal or better than another bike with the same build. It's how it runs and if you like it that matters.

Mark

Mark, I think you are most likely correct. Tell'em how the bike will be ridden and what is most important to the rider. Then don't second guess the porter, go with the suggestions if they make sense.

I went on some of the web sites listed above, read the dyno results to see what most 95" engines with similar equipment were producing. (I suggest other do that, there's good stuff there.) Seems like there is a ballpark that most fall within. But I'll still want more: you know where I'm coming from.

Thanks,

John
 

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Johnson did a 95" for me. It has his latest "CVN" style of heads, and it has the best throttle response of any HD I have ridden. Made 105HP/117TQ and it is over 100TQ from 2200 until 5400 RPM's, bike runs super.
 

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SILVER BULLET said:
Don't tell H-D that smaller ports work better. 1999 - 2005 heads had a 1.340 exhaust port and in 2006 it is 1.570 I agree that small ports work better and have more velocity.
Hasn't the stock exhaust valves on the twin cams always been 1.565 including 2006? When was it ever 1.340?
 

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bedemonster said:
Hasn't the stock exhaust valves on the twin cams always been 1.565 including 2006? When was it ever 1.340?
Hello bedemonster, Happy New Year to you my friend.

What Bullett was reffering to was the exhaust port diameters have changed from 1.340 I.D. as found in earlier models to 1.57 I.D. with the 2006 heads.

Valve sizes are still the same

The 2006 heads reportedly only require a modest amount of porting and give similar results to the big dollar aftermarket heads.

All the best, Ozzie
 
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