new 103's
Outstanding HDF Member
Joined: Oct 2006
Posts: 2,263
Likes: 36
From: Georgia Mountains
Somebody more knowledgeable than me needs to explain to the OP, in simple terms, the definition of cubic inches of displacement (88,96,103,110). What is bore? What is stroke? How do those mesurements combine to equal cubic inches?
The OP might think these numbers are horsepower?
My stock 88 has mild aftermarket cams (and a gear conversion). It breathes better and performs better than a STOCK 96. Cams and cubic inches are as different as apples and torque wrenches.
The OP might think these numbers are horsepower?
My stock 88 has mild aftermarket cams (and a gear conversion). It breathes better and performs better than a STOCK 96. Cams and cubic inches are as different as apples and torque wrenches.
Cruiser
Joined: May 2008
Posts: 116
Likes: 0
Class, there will be a test so pay attention...
"Bore" is the diameter of the piston, "Stroke" is the distance the piston moves from bottom dead center to top dead center when the crankshaft rotates.
(Pi/4) x Bore x Bore x Stroke x # of cylinders = displacement
Using the formula above, for a 96: 0.7854 (pi/4) x 3.75 (bore) x 3.75 (bore) x 4.375 (stroke) x 2 (# of cylinders) = 96.64 cu. inch and for a 103 it would be 0.7854 x 3.875 x 3.875 x 4.375 x 2 = 103.19 cu inch.
So, the difference between a 96 and a 103 is the bore (larger diameter piston/cylinders) has been changed from 3.75" to 3.875"...a difference of 1/8".
"Bore" is the diameter of the piston, "Stroke" is the distance the piston moves from bottom dead center to top dead center when the crankshaft rotates.
(Pi/4) x Bore x Bore x Stroke x # of cylinders = displacement
Using the formula above, for a 96: 0.7854 (pi/4) x 3.75 (bore) x 3.75 (bore) x 4.375 (stroke) x 2 (# of cylinders) = 96.64 cu. inch and for a 103 it would be 0.7854 x 3.875 x 3.875 x 4.375 x 2 = 103.19 cu inch.
So, the difference between a 96 and a 103 is the bore (larger diameter piston/cylinders) has been changed from 3.75" to 3.875"...a difference of 1/8".
Last edited by gtnot; Aug 20, 2010 at 11:38 AM. Reason: add a lil humor
Road Warrior
Joined: Jun 2007
Posts: 1,645
Likes: 2
From: South County, CA.
There's a big difference between a Stage 1 103" (Just bigger Jugs and an Intake) and Stage 2 (Jugs, Cams, and Intake)
Most of the 103"s are just jugs now. My local dealer is offering a 103 Stage 1 kit installed on new bikes for around $1000
Stage 2's are around $2000
And if you can't figure out thew difference between 96ci, and 10ci, it's time to take a refresher Math class!
Most of the 103"s are just jugs now. My local dealer is offering a 103 Stage 1 kit installed on new bikes for around $1000
Stage 2's are around $2000
And if you can't figure out thew difference between 96ci, and 10ci, it's time to take a refresher Math class!
Road Master
Joined: Feb 2010
Posts: 1,210
Likes: 1
From: LI, NY
A cylinder is the area a piston moves in.
Displacement is the size of the area that the piston moves in.
Area of a square is a flat two dimensional area so two dimensions/meaurements are needed to compute the area
2"x2" square has a area of 4 square inches
A box has three dimensions and so it needs three dimensions to determine it's area/volume
2"x2"x4" box has a volume of 16 cubic inches
A cylinder is a round box so the area for a circle A = pr2
(p=3.14) needs a third dimension height/length of the cylinder
Volume = pr2 x height
If a cylinder has a volume of 48 cubic inches how much displacement does the engine have?
Multiply the volume of a cylinder by the number of cylinders:
48 cu in x 2= 96 cu in
The length or width of a circle/cylinder is named the diameter. Being that the cylinder is made by boring a the round hole in an engine block the width is called a Bore. bore/diameter same thing
Being that piston travels thru the cylinder up and down these movements are called strokes. Stroke/length/height/ of a cylinder are same thing
Cams can not change the size of an engine's displacement/cylinder size.
To change displacement either the cylinder has to be bored to a larger size or the stroke made longer, or both.
Valves are same as doors to the cylinder. Let in air and fuel and lets out exhuast.
Cams are automatic door openers that control when and how much the valves open.
Cams from the factory are a compromise. The engine has to idle smooth, not waste fuel, keep emissions low, power.
Low air flow at low rpm the engine runs best with the valves only being opened a little, High air flow at WOT the engine runs best with the valves opened a lot. Cruising the valves only need to be opened up some where in between.
Every one has heard about spark advance and how distributors automatically advance and retard spark match engine need to produce power or fuel efficiency.
Electronic ignition does this still today.
Far back as 1975 auto engineers were working on having variable valve timing. This way the engine could act as it had several different camshafts to switch back and forth to meet changing engine loads.
Some new cars have variable valve timing now.
So changing cams only effects when the valves open, how much the valves open, how long the valves open and valve overlap. Does not change the size of the bore or stroke.
A cylinders exhaust valve and intake valve are both opened for a short time. This is known as valve overlap.
Displacement is the size of the area that the piston moves in.
Area of a square is a flat two dimensional area so two dimensions/meaurements are needed to compute the area
2"x2" square has a area of 4 square inches
A box has three dimensions and so it needs three dimensions to determine it's area/volume
2"x2"x4" box has a volume of 16 cubic inches
A cylinder is a round box so the area for a circle A = pr2
(p=3.14) needs a third dimension height/length of the cylinder
Volume = pr2 x height
If a cylinder has a volume of 48 cubic inches how much displacement does the engine have?
Multiply the volume of a cylinder by the number of cylinders:
48 cu in x 2= 96 cu in
The length or width of a circle/cylinder is named the diameter. Being that the cylinder is made by boring a the round hole in an engine block the width is called a Bore. bore/diameter same thing
Being that piston travels thru the cylinder up and down these movements are called strokes. Stroke/length/height/ of a cylinder are same thing
Cams can not change the size of an engine's displacement/cylinder size.
To change displacement either the cylinder has to be bored to a larger size or the stroke made longer, or both.
Valves are same as doors to the cylinder. Let in air and fuel and lets out exhuast.
Cams are automatic door openers that control when and how much the valves open.
Cams from the factory are a compromise. The engine has to idle smooth, not waste fuel, keep emissions low, power.
Low air flow at low rpm the engine runs best with the valves only being opened a little, High air flow at WOT the engine runs best with the valves opened a lot. Cruising the valves only need to be opened up some where in between.
Every one has heard about spark advance and how distributors automatically advance and retard spark match engine need to produce power or fuel efficiency.
Electronic ignition does this still today.
Far back as 1975 auto engineers were working on having variable valve timing. This way the engine could act as it had several different camshafts to switch back and forth to meet changing engine loads.
Some new cars have variable valve timing now.
So changing cams only effects when the valves open, how much the valves open, how long the valves open and valve overlap. Does not change the size of the bore or stroke.
A cylinders exhaust valve and intake valve are both opened for a short time. This is known as valve overlap.
Club Member
Joined: May 2007
Posts: 145,895
Likes: 821
From: 40 miles Northeast of Indy..
I love reading some newbies explain things... Really,, we need some good laughs in here every so often.
Heres one of the best articles Ive read on,,,, Stage 1-2-3-4 Explained..
real good reading and info for newbes to learn..
http://www.hdtalking.com/harley_davi...explained.html
Heres one of the best articles Ive read on,,,, Stage 1-2-3-4 Explained..
real good reading and info for newbes to learn..
http://www.hdtalking.com/harley_davi...explained.html
Club Member
Joined: May 2007
Posts: 145,895
Likes: 821
From: 40 miles Northeast of Indy..
Just by changing the cylinder you can increase the cubic inch displacement so that would be considered the bottom half of your engine including the cylinders, pistons and crank shaft. The cam is part of the top end witch is your cam and valves in the heads. The lobes on the cam opens and closes the valves so changing the cam gives you more lift keeping the valve open longer increasing intake and exhaust timing but nothing to do with displacement. hope that helps some.
U did get 2 things right bigger jugs ='s bigger CID.. And use bigger cams usually increase the valve openings, also the duration, overlap, lobe center. timing. and Lift.. chose by its needs..
Cyl are not the bottom half on a HD..
Cams are not located in the heads. The valves are
Last edited by oct1949; Aug 20, 2010 at 12:47 PM.
Club Member
Joined: May 2007
Posts: 145,895
Likes: 821
From: 40 miles Northeast of Indy..
Just talked to our master wrench yesterday...
He pointed out the new 103 power pack is not doing so well...not much more UMPH than a stock 96,
It cost, from what I've read is about $2k on new bikes and is nothing like a 103 SE BB kit, which has the cams and pistons included and can be done for almost the same $$$$.
He pointed out the new 103 power pack is not doing so well...not much more UMPH than a stock 96,
It cost, from what I've read is about $2k on new bikes and is nothing like a 103 SE BB kit, which has the cams and pistons included and can be done for almost the same $$$$.
Road Warrior
Joined: Mar 2010
Posts: 1,980
Likes: 16
From: USA
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Banned
Joined: Jul 2009
Posts: 911
Likes: 0
From: KY
I love reading some newbies explain things... Really,, we need some good laughs in here every so often.
Heres one of the best articles Ive read on,,,, Stage 1-2-3-4 Explained..
real good reading and info for newbes to learn..
http://www.hdtalking.com/harley_davi...explained.html
Heres one of the best articles Ive read on,,,, Stage 1-2-3-4 Explained..
real good reading and info for newbes to learn..
http://www.hdtalking.com/harley_davi...explained.html
Last edited by JerryL....; Aug 20, 2010 at 02:23 PM.
Seasoned HDF Member
Joined: Oct 2006
Posts: 5,977
Likes: 85
From: Nevada
Just talked to our master wrench yesterday...
He pointed out the new 103 power pack is not doing so well...not much more UMPH than a stock 96,
It cost, from what I've read is about $2k on new bikes and is nothing like a 103 SE BB kit, which has the cams and pistons included and can be done for almost the same $$$$.
He pointed out the new 103 power pack is not doing so well...not much more UMPH than a stock 96,
It cost, from what I've read is about $2k on new bikes and is nothing like a 103 SE BB kit, which has the cams and pistons included and can be done for almost the same $$$$.
I think your right about the additional power from what I hear as well. Set of cams should wake it up pretty well tho.